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Risk Analysis of Sea Turtle (Dermochelys coriacea & Caretta caretta) Nesting Season Bycatch in Florida Coastal Waters Due to Commercial Fishing Gear Regulations

Item

Title

Risk Analysis of Sea Turtle (Dermochelys coriacea & Caretta caretta) Nesting Season Bycatch in Florida Coastal Waters Due to Commercial Fishing Gear Regulations

Creator

Scoville, Marissa

Identifier

Thesis_MES_2023_ScovilleM

extracted text

RISK ANALYSIS OF SEA TURTLE (CARETTA CARETTA & DERMOCHELYS CORIACEA)
NESTING SEASON BYCATCH IN FLORIDA COASTAL WATERS DUE TO
COMMERCIAL FISHING GEAR REGULATIONS

by
Marissa L. Scoville

A Thesis
Submitted in partial fulfillment
of the requirements for the degree
Master of Environmental Studies
The Evergreen State College
June 2023

©2023 by Marissa L. Scoville. All rights reserved.

This Thesis for the Master of Environmental Studies Degree
by
Marissa L. Scoville

has been approved for
The Evergreen State College
by

___________________________
John C. Withey, Ph.D.
Member of Faculty

June 16, 2023
_______________________________
Date

Abstract
Risk Analysis of Sea Turtle (Caretta caretta & Dermochelys coriacea)
Nesting Season Bycatch in Florida Coastal Waters Due to
Commercial Fishing Gear Regulations
Marissa L. Scoville
Anthropogenic influences have negatively impacted sea turtles on a global scale. In the USA, the
commercial fishing industry decimated the population of all five sea turtle species that reside in
its waters due to aggressive overfishing that did not end until 1978, when they were listed the
United States Endangered Species Act of 1973. The USA commercial fishing industry still poses
a significant risk to these recovering sea turtle populations due to bycatch in fishing gear.
Bycatch interactions can injure or kill sea turtles due to the turtle being entangled in the gear,
which can result in strangulation, drowning, amputation of limbs, as well as both internal and
external injuries from fishing hooks. My research analyzes the risk commercial fishing gear
regulations pose to loggerheads (Caretta caretta) and leatherbacks (Dermochelys coriacea), in
waters up to 100 nautical miles off the coast of Florida. I used satellite relocation data of
loggerhead (n=34) and leatherback (n=11) sea turtles between 2005 to 2017 (provided by the Sea
Turtle Conservancy) and maps of 52 federally regulated fishing zones and their commercial
fishing gear (longline, trawl, net, dredge, pot and trap) restrictions to assess the association of
fishing regulations with hotspots of turtle activity. I used the kernel density function to identify
turtle relocation hotspots and overlaid these maps with the regulated fishing zones maps, using
the zonal statistics function to determine if any associations between hotspots and gear
restrictions emerged. I found that there is an association between higher turtle relocation kernel
density values and zones with greater longline and trawl restrictions. My results may help to
increase the awareness of commercial fisheries continued impacts on sea turtle populations and
lead to the implementation of future gear regulation to help mitigate sea turtle bycatch in Florida
waters.

Table of Contents
List of Figures ............................................................................................................................... vi
List of Tables ................................................................................................................................ ix
Acknowledgements ....................................................................................................................... x
Introduction ................................................................................................................................... 1
Literature Review ......................................................................................................................... 5
Background ....................................................................................................................................... 5
Sea Turtles ..................................................................................................................................... 5
Loggerhead................................................................................................................................. 6
Leatherback ................................................................................................................................ 8
Florida ......................................................................................................................................... 10
Geographical Distribution of Sea Turtles ............................................................................................ 12
Nesting Grounds ............................................................................................................................ 12
Breeding Habitat ............................................................................................................................ 13
Foraging grounds ........................................................................................................................... 14
Loggerheads ............................................................................................................................. 14
Leatherbacks ............................................................................................................................. 17
Migratory Corridors ....................................................................................................................... 20
Loggerheads ............................................................................................................................. 20
Leatherback .............................................................................................................................. 22
Commercial Fishing.......................................................................................................................... 23
Fishing Gear ................................................................................................................................. 23
Longline .................................................................................................................................. 24
Trawling .................................................................................................................................. 24
Net .......................................................................................................................................... 24
Pot and Trap ............................................................................................................................. 25
Dredge ..................................................................................................................................... 25
Bycatch Impacts ............................................................................................................................ 26
Longline .................................................................................................................................. 26
Trawl....................................................................................................................................... 28
Pot and Trap ............................................................................................................................. 29
Net .......................................................................................................................................... 29
Dredge ..................................................................................................................................... 30
Regulations................................................................................................................................... 31
Federal..................................................................................................................................... 31
State ........................................................................................................................................ 35
Regulated Fishing Zones ................................................................................................................. 35
Conclusion ....................................................................................................................................... 36
Methods ........................................................................................................................................ 39
Data Collection ................................................................................................................................ 39
Study Area ................................................................................................................................... 39
Species of Study ............................................................................................................................ 39
Regulated Fishing Zones and Commercial Fishing Gear Regulations ....................................................... 40
Geospatial Analysis .......................................................................................................................... 42
Fishing Zone Maps......................................................................................................................... 43

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Sea Turtle Maps ............................................................................................................................ 43
Kernel Density .............................................................................................................................. 45
Statistical Analysis............................................................................................................................ 45
Zonal Statistics .............................................................................................................................. 45
Analysis ....................................................................................................................................... 46

Results .......................................................................................................................................... 48
Gear Restrictions ............................................................................................................................. 48
Zonal Gear Restrictions ................................................................................................................... 48
Atlantic .................................................................................................................................... 48
Gulf of Mexico .......................................................................................................................... 48
Gear Type Restrictions.................................................................................................................... 49
Atlantic .................................................................................................................................... 50
Gulf of Mexico .......................................................................................................................... 50
Zonal Sea Turtle Kernel Density ........................................................................................................ 51
Atlantic ........................................................................................................................................ 51
Loggerheads ............................................................................................................................. 53
Gulf of Mexico .............................................................................................................................. 59
Loggerheads ............................................................................................................................. 61
Leatherbacks ............................................................................................................................. 65
Gear and Kernel Density Relationships ............................................................................................... 72
Regulated Fishing Zone Kernel Density and Gear Restrictions ................................................................ 72
Relationship Between Zone Density and Restricted Gear Type .............................................................. 73
Atlantic ........................................................................................................................................ 73
Loggerhead............................................................................................................................... 73
Gulf of Mexico .............................................................................................................................. 74
Loggerhead............................................................................................................................... 74
Leatherbacks ............................................................................................................................. 74
Discussion..................................................................................................................................... 76
Hotspots Usage................................................................................................................................. 76
Loggerheads ................................................................................................................................. 76
Leatherbacks ................................................................................................................................. 79
Migratory Corridors ....................................................................................................................... 81
Risk Assessment ............................................................................................................................... 82
Recommendations ............................................................................................................................ 84
Spatial Considerations ...................................................................................................................... 86
Conclusion ................................................................................................................................... 89
Bibliography ................................................................................................................................ 91

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List of Figures
Figure 1. Loggerhead DPS boundary map (Valverde & Holzwart, 2017). ....................................................... 7
Figure 2. Leatherback NWA DPS bounary map (National Marine Fisheries Service & U.S. Fish and Wildlife
Service, 2020). ............................................................................................................................ 8
Figure 3. Florida’s state and federal waters (Nalley, 2019)......................................................................... 10
Figure 4. Loggerhead Critical habitat map (NMFS Office Of Protected Resources, 2023). .............................. 14
Figure 5. Map of Florida coastal regions. Mid Atlantic Blight (MAB), South Atlantic Blight (SAB), Subtropical
Northwest Atlantic (SNWA), Eastern Gulf of Mexico (EGoM) Northern Gulf of Mexico (NGoM) and South
Gulf of Mexico (SGoM) (Pfaller et al., 2020). ................................................................................. 16
Figure 6. Foraging Hotspot map of individual NWA DPS loggerheads nesting in east central Florida coast (Ceriani
et al., 2017). .............................................................................................................................. 16
Figure 7. Internesting Kernel-estimated home-range utilization (KHRE) distributions of leatherbacks in the SAB
(Eckert et al, 2006). .................................................................................................................... 18
Figure 8. Seasonal leatherback postnesting high-use area kernel home-range utilization distributions (Eckert et al,
2006). ...................................................................................................................................... 19
Figure 9. Yearly kernel density map of postnesting leatherback foraging grounds. A) 2015, B) 2018, C) 2019 (Sasso
et al., 2021). .............................................................................................................................. 19
Figure 10. Map of the migration corridors of 14 loggerhead nesting in eastern central Florida. (A) Pink=north, blue=
south and green=resident. (B) dark pink= summer migration and light pink=winter migrations (Ceriani et al.,
2012). ...................................................................................................................................... 21
Figure 11. Postnesting migratory corridors of three from three Florida rookeries, (A) northwestern rookery, (B)
central western rookery and (C) eastern rookery, PTT tracked between 1998 to 2001. Migratory corridors:
yellow= eastern Florida Panhandle southwest to Yucatán Peninsula, Mexico, red= eastern Florida panhandle
southeast down coast, green= along northern coast of Cuba, blue= southeastern Florida coast to central
Atlantic Ocean (Foley et al., 2013). ............................................................................................... 21
Figure 12. Leatherback movements throughout Caribbean and Gulf of Mexico from 2015, 2018 and 2019.
Red=foraging, blue= migration, and orange/white/light blue=searching/foraging (Sasso et al., 2021). ......... 22
Figure 13. Kernel density map of leatherback post nesting high-areas of Gulf of Mexico, Caribbean and Northwest
Atlantic (Evans et al., 2021). ........................................................................................................ 22
Figure 14. Seasonal kernel density map of leatherback high-areas of Gulf of Mexico, Caribbean and Northwest
Atlantic (Evans et al., 2021). ........................................................................................................ 23
Figure 15. NOAA SEFSC Atlantic longline fishing regions and NOAA longline marine managed areas between
1986 to 2009 (Kot et al., 2010). Caribbean (CAR), Gulf of Mexico (GOM), Florida East Coast (FEC), South
Atlantic Blight (SAB), Mid Atlantic Blight (MAB), Northeast Coastal (NEC), Northeast Distant (NED, North
Central Atlantic, (NCA) Tuna North (TUN) and Tuna South (TUS). .................................................... 27
Figure 16. Study area and USA EEZ, 100 nautical miles of Florida Coast..................................................... 39
Figure 17. Regulated fishing zones in the Atlantic and Gulf of Mexico up to 100 nautical miles off Florida coastline.

............................................................................................................................................... 40
Figure 18. Analyzed Gulf of Mexico Zones. ........................................................................................... 41
Figure 19. Analyzed Atlantic regulated fishing zones. .............................................................................. 42
Figure 20. Leatherback relocations between 2005 to 2017 (n=11 individual turtles). ....................................... 44
Figure 21. Loggerhead relocations between 2009 to 2017 (n=34 individual turtles). ....................................... 44
Figure 22. Expanded kernel density (ESRI, n.d.). .................................................................................... 45
Figure 24. Expanded R 2 equation. ....................................................................................................... 47
Figure 23. Linear regression equation. ................................................................................................... 47
Figure 25. Counts of restrictions in both the Gulf of Mexico and Atlantic Ocean by gear type. ......................... 49
Figure 26. Counts of restrictions in the Atlantic by gear type. .................................................................... 50
Figure 27. Counts of restrictions in the Gulf of Mexico by gear type. .......................................................... 51

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Figure 28. Atlantic regulated fishing zones loggerhead kernel density: A) median B) mean C) standard deviation D)
max E) area. Atlantic Unregulated (AU), Stetson-Miami Terrace HAPC (SMT), Charleston Bump Closed
Area (CBCA), Allowable Octocoral Closed Area (AOCA), Pourtales Terrace HAPC (PT), East Florida Coast
(EFC), Longline Prohibited South of 27 10'N (LPS), Longline Prohibited North of 27 10'N (LPN), Florida
Keys National Marine Sanctuary (FKNMS) and Oculina Bank HAPC (OB). ......................................... 52
Figure 29. Florida Keys National Marine Sanctuary loggerhead KD hotspot map. .......................................... 56
Figure 30. Oculina Bank HAPC loggerhead KD hotspot map. .................................................................... 56
Figure 31. Longline Prohibited: North of 27 10'N (purple) and South of 27 10' loggerhead KD hotspot map. ...... 56
Figure 32. East Florida Coast loggerhead KD hotspot map. ....................................................................... 57
Figure 33. Allowable Octocoral Closed Area loggerhead KD hotspot map. ................................................... 57
Figure 34. Pourtales Terrace HAPC loggerhead KD hotspot map. ............................................................... 58
Figure 35. Charleston Bump Closed Area loggerhead KD hotspot map. ....................................................... 58
Figure 36. Stetson-Miami Terrace HAPC loggerhead KD hotspot map. ....................................................... 59
Figure 37. Atlantic Unregulated loggerhead KD hotspot map. .................................................................... 59
Figure 38. Gulf of Mexico regulated fishing zones loggerhead kernel density: A) median B) mean C) standard
deviation D) max E) area. Gulf of Mexico Unregulated (GoMU), Reef Fish Longline Restriction (RFLR),
Bottom Longline Prohibited (BLP), Reef Fish Stressed Areas, FL West Coast (RFSA-WC), Southwest Florida
Trawl Closure (SWFTC) and Tortugas Shrimp Sanctuary North (TSS-N). ............................................ 60
Figure 39. Southwest Florida Trawl Closure loggerhead KD hotspot map. .................................................... 64
Figure 40. Tortugas Shrimp Sanctuary North loggerhead KD hotspot map. ................................................... 64
Figure 41. Reef Fish Stressed Area, FL West Coast loggerhead KD hotspot map. .......................................... 64
Figure 42.Bottom Longline Prohibited loggerhead KD hotspot map. ........................................................... 64
Figure 43. Reef Fish Longline Restricted loggerhead KD hotspot map. ........................................................ 65
Figure 44. Gulf of Mexico Unregulated loggerhead KD hotspot map. .......................................................... 65
Figure 45. Gulf of Mexico regulated fishing zones leatherback kernel density: A) median B) mean C) standard
deviation D) max E) area. Gulf of Mexico Unregulated (GoMU), Reef Fish Longline Restriction (RFLR),
Bottom Longline Prohibited (BLP), Reef Fish Stressed Areas, FL West Coast (RFSA-WC), Reef Fish Stressed
Areas, FL, AL and MS (RFSA-MS), Middle Grounds HAPC (MG) and The Edges (Edges) ..................... 66
Figure 46. The Edges leatherback KD hotspot map. ................................................................................. 69
Figure 47. Reef Fish Longline Restricted leatherback KD hotspot map. ....................................................... 69
Figure 48. Middle grounds leatherback KD hotspot map. .......................................................................... 70
Figure 49. Gulf of Mexico Unregulated leatherback KD hotspot map. ......................................................... 70
Figure 50. Bottom Longline Prohibited leatherback KD hotspot map. .......................................................... 71
Figure 51. Reef Fish Stressed Areas: Fl West Coast and Fl, Al and MS leatherback KD hotspot map. ................ 71
Figure 52. Atlantic Ocean loggerhead regulated fishing zones gear counts and median kernel density do not have a
significant relationship (F1,8 = 1.28, p = 0.29, R2 = 0.14). ................................................................. 72
Figure 53. Gulf of Mexico loggerhead regulated fishing zones gear counts and median kernel density do not have a
significant relationship (F1,4 = 1.28, p = 0.32, R2 = 0.24). ................................................................. 72
Figure 54. Gulf of Mexico leatherback regulated fishing zones gear counts and median kernel density do not have a
significant relationship (F1,5 = 3.57, p = 0.12, R2 = 0.42). ................................................................. 73
Figure 55. Zone median kernel density and its relationship with gear type restrictions. A) Atlantic zones with
Loggerhead Median KD B) Gulf of Mexico zones with loggerhead median KD C) Gulf of Mexico zones with
loggerhead median KD................................................................................................................ 74
Figure 56. Loggerhead Relocation kernel density hotspots. 9 hotspots between 4 usage areas: eastern central Florida
coast (hotspot 1) Florida Keys (hotspots 2, 3 and 4) western central Florida coast (hotspots 5, 6 and 7) and
Florida panhandle (hotspots 8 and 9). ............................................................................................. 77
Figure 57. Leatherback relocation kernel density hotspots. 3 hotspots in the Florida panhandle (hotspots 1, 2 and 3).
High use areas are: Central Panhandle (CP) and South Panhandle (SP). ................................................ 80

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Figure 58. Sea turtle high use areas. Loggerhead: Big Bend (BB), Port Charlotte (PC), Cape Coral (CC), Bonita
Springs (BS), Key West (KW) and Palm Bay (PB). Leatherbacks: South Panhandle (SP) and Central
Panhandle (CP). ......................................................................................................................... 86
Figure 59. Atlantic Ocean regulated fishing zone overlaps with other zones. Yellow=overlap, white= no overlap and
black= n/a (same zone). Atlantic Unregulated (AU), Stetson-Miami Terrace HAPC (SMT), Charleston Bump
Closed Area (CBCA), Allowable Octocoral Closed Area (AOCA), Pourtales Terrace HAPC (PT), East Florida
Coast (EFC), Longline Prohibited South of 27 10'N (LPS), Longline Prohibited North of 27 10'N (LPN),
Florida Keys National Marine Sanctuary (FKNMS) and Oculina Bank HAPC (OB). ............................... 88
Figure 60. Gulf of Mexico regulated fishing zone overlaps with other zones. Orange=overlap, white= no overlap
and back= n/a (same zone). Unregulated-Gulf of Mexico (UGoM), Reef Fish Longline Restriction (RFLR),
Bottom Longline Prohibited (BLP), Reef Fish Stressed Areas, FL West Coast (RFSA-WC), Reef Fish Stressed
Areas, FL, AL and MS (RFSA-MS), Middle Grounds HAPC (MG), The Edges (Edges), Southwest Florida
Trawl Closure (SWFTC) and Tortugas Shrimp Sanctuary North (TSS-N). ............................................ 88

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List of Tables
Table 1. Florida nesting counts by county (FFWCC, 2023). ....................................................................... 13
Table 2. Fishing zones and their regulations within 100 nautical mile radius of Florida coast in the Atlantic Ocean.
Yes= allowed, No= not allowed and Never= zone is not open to any fishing/gear ever. (U.S. Fish and Wildlife
Service & Department of Interior, 2013). ........................................................................................ 37
Table 3. Fishing zones and their regulations within 100 nautical mile radius of Florida coast in the Gulf of Mexico.
Yes= allowed, No= not allowed and Never= zone is not open to any fishing/gear ever (U.S. Fish and Wildlife
Service & Department of Interior, 2013). ........................................................................................ 38
Table 4. Gear restrictions of Atlantic regulated fishing zones. Yes= allowed, No= not allowed. ........................ 42
Table 5. Gear restrictions of Gulf of Mexico regulated fishing zones. Yes= allowed, No= not allowed. .............. 42
Table 6. Atlantic regulated fishing zones loggerhead kernel density for median, mean, standard deviation, max and
area. All raw data except area was x1000. ....................................................................................... 53
Table 7. Gulf of Mexico regulated fishing zones loggerhead kernel density for median, mean, standard deviation,
maximum and area. All raw data, except area, is x1000. .................................................................... 61
Table 8. Gulf of Mexico regulated fishing zones leatherback kernel density for median, mean, standard deviation,
max and area. All raw data except area was x1000. ........................................................................... 65

ix

Acknowledgements
I would like to sincerely thank Dr. Daniel Evans from the Sea Turtle Conservancy for allowing
me access to sea turtle relocation data. He was extremely gracious and generous providing nearly
a decade’s worth of data. Dr. Evans’ work has is has been instrumental in my ability to build and
research my thesis and for that I cannot be more grateful.
Thank you to my thesis reader John Withey; without your feedback and support I would not have
been able to finish my thesis. I greatly apricate all the time and effort you have provided working
with me throughout this process.
I would like to extend my deepest gratitude to my fiancée. He has provide unwavering support,
patience, and love throughout the long journey that is the thesis process. Thank you for being
with me through every step and never allowing me to doubt myself or abilities.

x

Introduction
When we think of Florida’s white sandy beaches and crystal-clear waters, too few of us
remember the creatures that call this region home. Sea turtles are one such group of creatures.
Seven species of sea turtles roam the oceans worldwide, five of which are regularly found in the
waters of the USA. All seven species of sea turtles are listed as endangered or threatened under
the United States Endangered Species Act of 1973 and are all facing a myriad of anthropogenic
threats, such as bycatch. Groups such as The National Oceanic and Atmospheric Administration
(NOAA), Florida Fish and Wildlife Conservation Commission (FFWCC) and the Sea Turtle
Conservancy (STC) are making efforts to better conserve and protect them (Sea Turtle
Conservancy, n.d.; NOAA, 2021).
Threats to sea turtles are varied and come in a wide range of different conservation needs.
A few of the most prevalent and negatively impactful threats are climate change, habitat
degradation, and pollution. Climate change poses risks to turtle due to potential warming causing
a shift in the populations sex ratios due to temperature-dependent sex determination, rising sea
levels reducing natal nesting beaches, and altered wind and ocean currents impacting migratory
patterns, as well as many other risks (Poloczanska et al., 2009). Habitat degradation creates risks
for turtles due to humans building on nesting beaches and in marine habitats used for foraging,
breeding, migration etc., which can result in light pollution disorienting hatchlings, reduced food
availability and reduced population interactions for breeding (NOAA, 2021). Pollution poses risk
in various ways; however, trash pollution is the most common. For instance, garbage in the water
column can turtles to become entrapped or be ingested, which can result in gut blockages, and
both can lead to injury or death (Carr, 1987).

1

While there are many threats to sea turtles, one that stands out the most due to its dark
past with the species is fishing. Prior to the Endangered Species Act of 1973, sea turtles were
regularly fished commercially in the USA, with landing reports as recently as 1978 (Witzell,
1994). All five of the USA sea turtle’s species (green, Chelonia mydas; loggerhead, Caretta
caretta; Kemp's ridley, Lepidochelys kempi; hawksbill, Eretmochelys imbricata; and leatherback,
Dermochelys coriacea) were fished, with varying degrees of demand and used for their meat, oil,
and shells 1978 (Witzell, 1994). In many states where this fishing was most common, such as
Texas and Florida, Canneries were even opened, indicating the size and severity of the sea turtle
commercial fishing industry, however by the 1900s the turtle populations had begun to decline
and thus the industry with it (Witzell, 1994). The population pressures that sea turtles faced were
caused by overfishing, and these affects are still seen in present day. Today, sea turtles are only
caught via bycatch when fishing for their other species such as shrimp or yellow finned tuna
(Epperly et al., 2002; Kot et al., 2010). Bycatch is when a non-targeted species is caught
accidently by fishermen, in this case the accidental catch of loggerhead and/or leatherback sea
turtles (Gardner et al., 2008; Evans et al., 2021; Ceriani et al., 2017). Bycatch interactions can
result in the injury and mortality of turtles due to entanglement in gear. As of 2007, there was an
estimated 137,800 interactions through bycatch and estimated 4,600 deaths annually of sea
turtles caught in USA fisheries (Finkbein et al., 2011). Though protections are now placed
preventing the intentional landing of sea turtles in the USA, bycatch still poses a significant
threat to these recovering populations. Longlines, trawls, nets, dredges and pot and traps are the
most commonly used commercial fishing gear all of which have been linked to sea turtle bycatch
(USFWS & DOI, 2013; Ripple, 1996; Finkbeiner, et al., 2011; Gilman et al., 2017).

2

To help mitigate the impact of bycatch, commercial fishers must abide by strict
restrictions and regulations to help conserve the sea turtle populations. Federal and state
regulations have been placed in various regions across the USA Coastal water which regulated
gear uses and fishing methods allowed (USFWS & DOI, 2013; FAC & FAR, 2023; Florida
Legislature, 2023). Not all regulations were put in places for the protection of sea turtles,
however they still indirectly benefit them by reducing fishing pressures. Additional regulations,
such as the use of Turtle Excluder Devices (TEDS), gangion length, hook type and size, soak
times, and mesh sizes, were put in place at both state and federal levels with the aim to reduce
bycatch (USFWS & DOI, 2013; FAC & FAR, 2023; Florida Legislature, 2023). These
mitigation efforts have proven to substantially reduce bycatch but did not eliminate it and some
fishing methods still have higher than preferred sea turtle bycatch rates.
For the purposes of this study, I focused on two species of sea turtles off the coast of
Florida, the loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea). Florida and
its coastal waters are a region of vital habitat used by sea turtles for nesting, breeding, foraging
and migration, where loggerheads are commonly found as well as leatherbacks but to a lesser
extent due to their smaller global population size (National Marine Fisheries Service & U.S. Fish
and Wildlife Service, 2020). Understanding loggerhead and leatherback sea turtles’ movements
is another beneficial step to reduce potential bycatch from commercial fishing industries. This
leads me to my thesis questions: 1) What risk does the interaction between sea turtle (loggerhead
and leatherback) movements and Florida’s fishing zones pose to the two sea turtle species during
nesting season? 2) How could understanding this interaction, of relocation and regulation, reduce
the bycatch of these two species? To answer these questions, I used relocation (movements of
individual turtles from one location to another) data of loggerheads and leatherbacks, between

3

2005 to 2017 during nesting season, to create kernel density hotspots in order to determine where
turtle densities were the highest. I then overlayed this with the federal regulated fishing zones up
to 100 miles off the coast of Florida, in order to analyze the interaction between these zones and
their gear restrictions with the loggerhead and leatherback densities. This allowed me to best
analyze the risks that these two species are facing from commercial fisheries and make
recommendations accordingly. I hypothesized that 1) regulated fishing zones with higher gear
restrictions will be associated with higher turtle relocation densities, 2) regulated fishing zones
with higher longlines and trawl restrictions will be associated with higher turtle relocation
densities. My null hypothesizes are 1) regulated fishing zones with higher gear restrictions will
not have any different turtle relocation densities, 2) regulated fishing zones with higher longlines
and trawl restrictions will not affect turtle relocation densities.

4

Literature Review
This review will first focus on the sea turtle species (loggerhead and leatherback)
themselves by looking into the background of each, consisting of morphology, diet, range, U.S.
Endangered Species Act listing, and reproduction. Then I will analyze the current commercial
fishing industry, fishing zones, fishing gear (longline, trawl, pot and trap, net and dredge),
bycatch history and regulations. After this I will further investigate the geographical distribution
of sea turtles along the coasts of Florida. Lastly, I will discuss the relationship between the
bycatch and geological distribution of sea turtles in Florida. This pathway will guide the
understanding of how to reduce future sea turtle bycatch in the future.

Background
This section focuses on the two sea turtle species, loggerheads, and leatherbacks, in the
coastal waters of Florida. This will allow for a better understanding of the study outcomes and
provide context to the species and regulations in place.

Sea Turtles
Every species of sea turtle has a specialized morphology, diet, and reproductive ranges
and behaviors that have evolved to best thrive in the marine ecosystem. Considering these factors
can provide insight into their movements and why they are in a specific area. For example,
understanding their diet and range helps identify foraging grounds, which is key to the needs for
their movements. Similarly, their reproductive habits help us understand why they make
migrations and when these migrations may be more likely. Below, these species traits for both
loggerhead and leatherbacks are explored.

5

Loggerhead
Loggerheads are a highly migratory species, found globally in both temperate and
tropical regions of the Gulf of Mexico, Mediterranean and the 3 major oceans Atlantic, Indian,
and Pacific (Lohe & Possardt, 2021; NOAA, 2022, National Park Service, 2023). This species
has 9 distinct population segments (DPS), which are North Pacific Ocean DPS, Mediterranean
Sea DPS, Northeast Atlantic Ocean DPS, North Indian Ocean DPS, South Pacific Ocean DPS,
Northwest Atlantic Ocean DPS, South Atlantic Ocean DPS, Southeast Indo-Pacific Ocean DPS,
and Southwest Indian Ocean DPS (Figure 1; Lohe & Possardt, 2021; Valverde & Holzwart
2017). Each DPS is determined by the nesting beach fidelity, genetic discontinuity, and physical
isolation of each population (Lohe & Possardt, 2021). With an estimated global population count
of between 40,000 and 50,000 nesting females (males are not counted in population as they do
not surface on beaches causing counts to be unreliable), each of these DPS are listed under the
Endangered Species Act of 1973 as either threatened or endangered (Sea Turtle Conservancy,
n.d.; United states, 1973). This study is examining the population that is found in the Western
mid-Atlantic and Gulf of Mexico, which would be the Northwest Atlantic Ocean (NWA) DPS
(Lohe & Possardt, 2021; NOAA, 2022; United states, 1973). The Northwest Atlantic Ocean DPS
is listed as threatened (United States, 1973). This population of loggerheads mainly nests in
South Florida, USA and Oman (NOAA, 2022a). The majority of the estimated 100,000
loggerhead nests found in the USA annually are in Florida (NOAA, 2022a). The abundance of

6

loggerheads inhabiting the Gulf of Mexico and Atlantic Ocean waters surrounding Florida makes
it an excellent study area.

Figure 1. Loggerhead DPS boundary map (Valverde & Holzwart, 2017).

Loggerhead morphology, diet and reproduction is relatively simple, and consistent with
other members of the sea turtle family. The average loggerhead has a carapace length of 36
inches and a total weight of 250 pounds (National Park Service, 2023; NOAA, 2022). The
coloration of loggerheads varies throughout their body, with the top of their body being darker
colored than the bottom, to best blend in with the water column. Their carapace is reddish-brown
while the plastron is pale-yellow, and the top of flippers are brown while the bottom of flippers
are pale yellow. Named for its distinctive large head, the loggerhead has strong jaws used to feed
on crustaceans, mollusks and other prey such as crabs, fish and conches (Plotkin et al., 1993;
National Park Service, 2023). While they are preferred carnivores, loggerhead are known to eat
other plant matter as well, especially in early stages of life (NOAA, 2022a). They have three
main life stages, hatchling, juvenile and adult. Hatching and juveniles remain in oceanic habitats
where they rely of food sources such as Sargassum (a pelagic sea grass) and gelatinous

7

zooplankton, whereas in adulthood they return to neritic habitats which allows for a primarily
carnivorous diet (Lohe & Possardt, 2021). Adult loggerheads make frequent migrations and will
often forage in oceanic as well as neritic habitats (Plotkin et al., 1993). Breeding is one reason
turtles migrate; at roughly 30 years of age female loggerheads reach sexual maturity and will
return to their natal beaches to nest every 2-4 years (Lohe & Possardt, 2021; NOAA, 2022a).

Leatherback
Similar to loggerheads, leatherbacks are also a highly migratory species, found globally
in temperate and tropical regions of the Atlantic, Pacific, and Indian Oceans (NOAA, 2022b).
This species has 7 DPS, which are The Northwest Atlantic DPS, Southwest Atlantic DPS,
Southeast Atlantic DPS, Southwest Indian DPS, Northeast Indian DPS, West Pacific DPS and
East Pacific DPS (Figure 2; National Marine Fisheries Service & U.S. Fish and Wildlife Service,
2020). The population of leatherbacks is estimated to be 34,500 nesting females globally
(National Marine
Fisheries Service &
U.S. Fish and Wildlife
Service, 2020). Due to
their low global
population numbers,
the leatherback’s
protection status from
the ESA is endangered
in every DPS (National
Marine Fisheries

Figure 2. Leatherback NWA DPS bounary map (National Marine Fisheries Service & U.S.
Fish and Wildlife Service, 2020).

8

Service & U.S. Fish and Wildlife Service, 2020; NOAA, 2022b; U.S. Fish and Wildlife Service,
n.d.). This study used data from the largest DPS, the Northwest Atlantic (NWA) DPS, with an
estimated population of 20,659. Turtles from this DPS nest in the southeast United States and
Caribbean Region DPS (National Marine Fisheries Service & U.S. Fish and Wildlife Service,
2020), and the abundance of leatherbacks nesting in Florida make it a good study area for this
species as well.
The diet and morphology of leatherbacks are unique among the sea turtles. They are the
largest sea turtle in the world, at 5 to 6 feet in length and an average weight of 1,000 pounds
(National Marine Fisheries Service & U.S. Fish and Wildlife Service, 2020; NOAA, 2022b; U.S.
Fish and Wildlife Service, n.d.). The leatherback carapace has seven ridges that are black with
white/pink spots and comprised of fatty connective tissue over dermal bones instead of the
keratinized scutes, which all other sea turtle species have (National Marine Fisheries Service &
U.S. Fish and Wildlife Service, 2020; NOAA, 2022b). Their jaws are sharp and pointed toothlike cusps with backward-pointing spines down their mouth and throat to assist with consuming
their prey (National Marine Fisheries Service & U.S. Fish and Wildlife Service, 2020; NOAA,
2022b). The prey of choice for leatherbacks of all life stages are gelatinous creatures such as
jellyfish (Cnidaria), tunicates (Tunicata/Urochordata), and ctenophores (Ctenophora) (National
Marine Fisheries Service & U.S. Fish and Wildlife Service, 2020; NOAA, 2022b). As this diet
has a low nutrient and calorie density, they must consume large quantities of prey, which leads to
the leatherback’s wide foraging distribution. The NWA DPS forage in the waters of the Gulf of
Mexico, Atlantic Ocean and Mediterranean Sea, with high-use regions in central and eastern
Atlantic waters and seasonally along the eastern U.S. coast (April to June and October to

9

December), northeast Gulf of Mexico (August- September) and off Canada (July to December)
(National Marine Fisheries Service & U.S. Fish and Wildlife Service, 2020).
The leatherbacks have 3 main life stages post hatching, which consist of hatchling,
juvenile and adult. There is little known about leatherback hatchlings and juveniles, they are
generally found in warm tropical waters, grow much more rapidly than the other sea turtles
species and are believed to consume gelatinous prey (National Marine Fisheries Service & U.S.
Fish and Wildlife Service, 2020). Adult leatherbacks migrate from foraging areas to the waters
off nesting beaches (natal beach region) every 2- 4 years once they hit sexual maturity between 9
to 20 years of age (National Marine Fisheries Service & U.S. Fish and Wildlife Service, 2020;
NOAA, 2022b).

Florida
Florida coastal waters
are part of both the Gulf of
Mexico (western Florida) and
the Atlantic Ocean (eastern
Florida). State waters extend
off the coastline, three nautical
miles into the Atlantic and nine
nautical miles into the Gulf of
Mexico, and federal waters
extend 200 nautical miles off

Figure 3. Florida’s state and federal waters (Nalley, 2019).

of the end of the state waters (Figure 3; Nalley, 2019). Extending 200 nautical miles of the

10

coastline of the United States (U.S.) is the U.S. Exclusive Economic Zone (EEZ), where the U.S.
has control over the marine resources (NOAA, 2023a).
Florida’s ecology and geography determine the productive marine ecosystem that allows
sea turtles to thrive there. Coastal water zones throughout the world make up 30% of the ocean’s
net primary productivity (Alongi, 2020). Upwelling, freshwater inputs (estuaries), and
interactions with the continental shelf provide high levels of nutrients into Florida’s coastal
waters (Alongi, 2020). Wind stress along the West coast of Florida creates coastal upwelling in
the Gulf of Mexico, and the boundary current response of the Gulf stream to the continental
shelf, on the Eastern coast of Florida, creates coastal upwelling in the Atlantic (Smith, 1982). In
the western Gulf of Mexico upwelling varies based on seasons, with summer having the highest
rates of upwelling (Zavala-Hidalgo, 2014). Sargassum (brown macroalgae) is common in the
surface waters on both sides of Florida (Gulf of Mexico and Atlantic) and commonly forms in
large groups created raft-like structures (SAFMC, 2002). The Sargassum plays host to a diverse
planktonic community, creating a draw for a myriad of species that feed on them - over one
hundred species of vertebrates, invertebrates, micro- and macro-epiphytes and fungi (United
States & National Marine Fisheries Service, 2013; Richardson & McGillivary, 1991). In regions
in the western North Atlantic, such as the Gulf Stream and the Sargasso Sea, where Sargassum
production is the highest, the Sargassum accounts for 60% of all primary production in the
surface waters and is more productive than the core of the Gulf stream (National Marine
Fisheries Service & U.S. Fish and Wildlife Service, 2020; Richardson & McGillivary, 1991).
Peak Sargassum production occurs in July or early August in the southeastern U.S (United States
& National Marine Fisheries Service, 2013).

11

Geographical Distribution of Sea Turtles
Nesting Grounds
Florida is heavily used as nesting grounds for many sea turtles. In 2022, there was a total
of 155,641 nests found, with 116,765 loggerhead and 1,848 leatherback found over 27 counties
in Florida (Table 3) (Florida Fish And Wildlife Conservation Commission [FFWCC], 2023). In
Florida nesting season occurs May to September for leatherbacks, while loggerheads nest from
June to September (National Marine Fisheries Service & U.S. Fish and Wildlife Service, 2020).
The NWA DPS of both loggerhead and leatherback are the sea turtle populations typically
nesting in the Florida region (TEWG, 2007; Dodd, 1988). Both turtles’ species have similar
nesting preferences that are supported by the Florida beach environment; steeply sloped, coarsegrained sandy beaches backed by dunes and/or vegetation that have limited obstacles (coral, rock
etc.) and are easily accessible from the sea (Hendrickson & Balasingham, 1966; Provancha &
Ehrhart 1987; TEWG, 2007; Kelly et al., 2017; Miller et al., 2023). Florida’s ecology supports
these nesting requirements, has 825 miles of beach throughout the state, sandy beaches with
dunes and vegetation (grasses, [Schizachyrium maritimum], subshrubs [Chrysoma
pauciflosculosa], shrubs, [Ceratiola ericoides] etc.) (Clark, 1993; Johnson, 1997). 80% of all
loggerhead nesting activity in the USA occurs along the Florida east coast (Ceriani et al., 2012).
leatherbacks in the NWA DPS nest throughout the NW Atlantic Ocean and Wider Caribbean
Region, including the U.S. mainland where Florida is the primary nesting ground (NMFS,
NOAA, & USFWS, 2020). Leatherback nesting in Florida is advantageous due to the easier
access for hatchlings to reach the Gulf Stream, which allows them easy transport to northern
oceanic foraging grounds (NMFS, NOAA, & USFWS, 2020). Overall, Florida is a vital nesting
ground for the leatherbacks and loggerhead sea turtles.

12

Table 1. Florida nesting counts by county (FFWCC, 2023).

East Coast
Florida County

West Coast
Loggerhead

Leatherback

Florida County

Loggerhead

Leatherback

Nassau

284

0

Collier

1,983

1

Duval

278

4

Lee

2,732

0

St Johns

1,154

15

Charlotte

2,031

0

Flagler

1,008

8

Sarasota

7,771

0

Volusia

4,626

23

Manatee

1,165

1

Brevard

31,623

143

Hillsborough

120

0

Indian River

7,547

106

Pinellas

488

0

St Lucie

7,163

251

Franklin

686

0

Martin

11,779

720

Gulf

507

0

Palm Beach

28,922

536

Bay

152

0

3,225

28

Walton

59

0

Miami-Dade

863

11

Okaloosa

28

0

Monroe

457

0

Santa Rosa

15

0

---

---

Escambia

99

1

98,929

1,845

TOTALS

17,836

3

Broward

--TOTALS

Breeding Habitat
Breeding habitat occurs wherever males and females interact during breeding season, this
is usually near the shore of nesting beaches (National Marine Fisheries Service & U.S. Fish and
Wildlife Service, 2020). Loggerheads have areas two breeding areas in the Florida region that
have been identified: (1) 200m offshore of Southern Florida between the Marquesas Keys and
the Martin County lines and (2) in southern waters offshore of Cape Canaveral, Florida (Figure
4; NMFS Office Of Protected Resources, 2023; FFWCC, 2023). A subgroup of the loggerhead
NWA DPS, known as the Peninsular Florida Recovery Unit, found that male turtles prefer
eastern Florida as breeding grounds (Pfaller et al., 2020). Leatherbacks currently do not have
breeding grounds identified in Florida region, however, due to the large population that nest in
this region it is reasonable to assume that breeding takes places in the waters offshore of more
prevalent nesting beaches in counties such as Martin, Palm Beach and St Lucie (Table 1;

13

FFWCC, 2023). These three counties with the highest nesting numbers are all located on the
eastern coast of Florida. Breeding habitats for sea turtles are currently the subject of ongoing
research, but little is currently known about possible breeding grounds in Florida.

Figure 4. Loggerhead Critical habitat map (NMFS Office Of Protected Resources, 2023).

Foraging grounds
Loggerheads and leatherbacks have different diets, and thus have different needs for their
foraging grounds. Below, I explore the foraging grounds of each species in the Florida region.

Loggerheads
The NWA DPS loggerheads’ foraging habitat is primary made up of neritic (nearshore)
environments. Loggerheads have different foraging needs throughout the lifespan and neritic
foraging grounds are easily accessible to newly hatched and juvenile turtles (who prefer
Sargassum), nesting females, adult resident (turtles remaining in Florida year-round), and
seasonal migraters (Griffin et al., 2013). Foraging grounds typically do not exceed water depths

14

of 200m and are along the continental shelf, in estuaries, bays, and sounds (Griffin et al., 2013,
United States & National Marine Fisheries Service, 2013). One study found that 63 out of 65
loggerheads tracked used foraging habitat along the continental shelf (Griffin et al., 2013). These
neritic environments are highly productive, particularly in benthic biota, which is vital for
loggerheads, considering that their diet primarily consists of crustaceans, (Alongi, 2020; National
Park Service, 2023; United States & National Marine Fisheries Service, 2013). Foraging grounds
must have sufficient availability and quality of prey as well as waters above 10° C (United States
& National Marine Fisheries Service, 2013).
Sargassum is an important foraging location, as well as shelter, for post-hatchling and
juvenile loggerheads (Witherington, 2002). Loggerheads in the early life stages are known to be
attracted to Sargassum and show foraging behavior when found with Sargassum (United States
& National Marine Fisheries Service, 2013). High densities of post-hatchling loggerheads have
been found in Sargassum off the coast of Florida (Witherington, 2002). Due to the importance of
Sargassum zones to early life stages of loggerheads, it has been labeled as critical loggerhead
habitat (Figure 4).
Foraging grounds in Florida expand along the continental shelf in the Atlantic and Gulf
of Mexico, with much foraging also occurring outside of the Florida region. Multiple studies
found that the South Atlantic Blight (SAB), Subtropical Northwest Atlantic (SNWA), Eastern
Gulf of Mexico (EGoM) and Northern Gulf of Mexico (NGoM) were all used by loggerheads as
foraging grounds (Figures 5&6) (Griffin et al., 2013; Pfaller et al., 2020; Ceriani et al., 2017;
Ceriani et al., 2012). These regions all have areas that intersect with the 100 nautical mile study

15

radius off Florida, and thus will be a focus of
discussion. The Mid Atlantic Blight (MAB),
South Gulf of Mexico (SGoM) and North Atlantic
have been found to be home to much loggerhead
foraging habitat, however as it is out of the study
radius they will not be discussed (Griffin et al.,
2013; Pfaller et al., 2020; Ceriani et al., 2017;
Ceriani et al., 2012). A 2013 study of 68 adult
female loggerhead tracked between 1998 to 2008
fund the 13 % foraged in the SAB from April to
October, and 21% foraged year-round in between

Figure 5. Map of Florida coastal regions. Mid Atlantic Blight
(MAB), South Atlantic Blight (SAB), Subtropical Northwest
Atlantic (SNWA), Eastern Gulf of Mexico (EGoM) Northern
Gulf of Mexico (NGoM) and South Gulf of Mexico (SGoM)
(Pfaller et al., 2020).

the EGoM and the SNWA (Griffin et al., 2013). A 2017
study of 749 loggerheads nesting along the EGoM,
SAB and SNWA coasts of Florida identified seven
foraging hotspots, three of which are within the 100mile radius of this study off Florida; the three hotspots
are (1) SAB, east central coast of Florida, (2) SNWA,
Florida Keys and (3) EGoM, west coast of Florida
(Figure 6; Ceriani et al., 2017). The east central Florida
foraging hotspot consistently had the highest usage
(mean=0.31). This 2017 study also found that Northern
foraging loggerheads had less successful reproductive
nesting, as those from the southern foraging grounds,

Figure 6. Foraging Hotspot map of individual NWA
DPS loggerheads nesting in east central Florida
coast (Ceriani et al., 2017).

16

with the two hotspots from the SNWA (Florida Keys and Bahamas) having higher annual
reproductive success (Ceriani et al., 2017). Between 2008 and 2010, 14 female loggerheads were
tracked post-nesting and it was found that 61% foraged in the Mid Atlantic Blight (MAB) and
SAB, with 4 turtles remaining year-round in eastern central Florida waters of Cape Canaveral
(Ceriani et al., 2012). Four other loggerheads remained year-round in the SNWA for foraging
(Ceriani et al., 2012). A 2020 study of loggerheads in two subgroups of the NWA DPS, Northern
Recovery Unit (NRU) and Peninsular Florida Recovery Unit (PFRU), found that 13.4% foraged
in the SAB and 2.2% in the SNWA (Pfaller et al., 2020). The PFRU was broken further into two
more groups, the eastern Florida PFRU and the western Florida PFRU. The PFRU foraging
hotspot breakdown within the Florida region was 50% in SNWA with 18% in SAB and 16%
EGoM for the eastern Florida PFRU and 47% in EGoM w29% in SNWA, and 14% in NGoM
(Pfaller et al., 2020). The NRU foraging hotspots within the Florida region were 14% in SAB
and 3% in SNWA (Pfaller et al., 2020). Foraging in the Florida region is vital to loggerhead
population survival.

Leatherbacks
Leatherbacks have a very wide range of foraging, with the species found globally. They
are known to forage in tropical to temperate waters and dive to depths of more than on one
kilometer (National Marine Fisheries Service & U.S. Fish and Wildlife Service, 2020; NOAA,
2022b). The NWA DPS leatherbacks in particular, have a unique foraging range as they have
been sighted as far north as Norway and Iceland (NMFS, NOAA, & USFWS, 2020). This DPS
prefers foraging in coastal (along the continental shelfs) and pelagic waters of Gulf of Mexico,
and North to central Atlantic Ocean with the eastern and southeastern U.S. coast being a
common foraging region (TEWG, 2007). Inter-nesting females forage within 100 km of nesting

17

regions, and as Florida is a common nesting region for leatherbacks, foraging here is vital
(NMFS, NOAA, & USFWS, 2020; FFWCC, 2023). Leatherbacks must forage in such a farranging migratory fashion as they must maximize their caloric intake due to the low caloric
density of their diet of gelatinous organisms (National Marine Fisheries Service & U.S. Fish and
Wildlife Service, 2020).
When looking at the region of study (Florida), most of the foraging is along the
continental shelf and seasonal, however there is evidence of some resident leatherbacks (TEWG
2007; Fossette et al., 2014; Eckert et al., 2006; Sasso et al., 2021; Evans et al., 2021). For the
purpose of consistency, the same regional break down of Florida coastal waters as used in the
2020 Pfaller et al. study will be used. The regional breakdown is as follows, MAB, SAB, EGoM,
NGoM, SGoM, and SNWA (Figure 5). In 2014, Fossette et al. found foraging ground throughout
the Atlantic Ocean by Satellite tracking of 106 leatherback turtles. Seasonal high-use foraging
grounds along eastern U.S. continental shelf (MAB and SAB) from April to June (start of nesting
season) and October to December, whereas the northeast Gulf of Mexico (EGoM and NGoM)
seasonal high-use was between August to September (end of nesting season) (Fossette et al.,
2014; NOAA, & USFWS,
2020). A study between 2000 to
2002 of 10 satellite tracked
female leatherbacks off the
eastern Florida coast (SAB) has
similar findings as Fossette et al.
(Eckert et al., 2006). This study
found high-use ‘internesting’

Figure 7. Internesting Kernel-estimated home-range utilization (KHRE)
distributions of leatherbacks in the SAB (Eckert et al, 2006).

18

(between nesting emergences) foraging grounds 2 to 60 km offshore SE of Cape Canaveral,
Florida and up to 215 km along the eastern Florida coast from Cape Canaveral (Figure 7) as well
as post nesting (after all nesting has finished) seasonal high-use foraging in the SAB in spring,
fall and summer
months (Figure 8)
(Eckert et al., 2006). A
2021 study by Sasso et
al. (2021) found that
the western Florida
(NGoM and EGoM)
were high-use foraging
grounds for postnesting
leatherbacks (Figure 9).

Figure 8. Seasonal leatherback postnesting high-use area kernel home-range utilization
distributions (Eckert et al, 2006).

The NGoM and EGoM
foraging zones prove to
be advantages due to
prey abundance and
proximity to nesting
regions (Sasso et al.,
2021). Overall, the
coastal waters in

Figure 9. Yearly kernel density map of
postnesting leatherback foraging grounds.
A) 2015, B) 2018, C) 2019 (Sasso et al.,
2021).

Florida prove to be a

19

highly used foraging grounds for leatherbacks.
Migratory Corridors
Migratory corridors are the movement pathways of animals between seasons. Both
loggerhead and leatherback are highly migratory species, migrating between regions for different
seasonal needs breeding, nesting, and foraging (Sasso et al., 2021; Ceriani et al., 2012; United
States & National Marine Fisheries Service, 2013). Having a strong understanding of the
migratory corridors in the Florida coastal waters allows better understanding of the turtle’s relocations and how fisheries could impact them. The regional breakdown of Florida coastal waters
(MAB, SAB, EGoM, NGoM, SGoM, and SNWA) from Pfaller et al. (2020) will be used. Only
adult turtle migratory corridors will be discussed.

Loggerheads
Migratory corridors of loggerheads in Florida constantly stayed along the continental
shelf; some turtles do migrate into oceanic environments however those are outside the range of
this study (Griffin et al., 2013; Foley et al., 2013). Loggerheads constantly showed three
migratory strategies when moving between foraging grounds or to/from nesting grounds, largescale (migrated between two or more regions), small scale (migrated short distances with in one
region) and resident (does not migrate, same area year-round) (Ceriani et al., 2017). In 2013
study by Foley et al., identified four migratory corridors from three Florida rookeries
(northwestern rookery, central western rookery and eastern rookery), (1) along the northern coast
of Cuba (Figure 10B&C), (2) southeastern Florida coast to central Atlantic Ocean (Figure 10C),
(3) eastern Florida Panhandle southwest to Yucatán Peninsula, Mexico (Figure 10A) and (4)
eastern Florida panhandle southeast down coast (Figure 10A). Corridors 1, 2, 3 and 4 are all
large-scale migratory corridors as 1’s migration path is between three regions (NGoM, EGoM
and SGoM), 2’s path is between three regions (EGoM, SNWA and SAB), 3’s path is between

20

three regions (NGoM, EGoM and SGoM) and 4’s 3’s path is between three regions (NGoM,
EGoM and SNWA) (Foley et al., 2013; Ceriani et al., 2017). The 2012 study by Ceriani et al.,
found postnesting two migration corridors of 14 loggerhead nesting in eastern central Florida,
referred to as “north” (seasonal migrations, SAB in winter and MAB in summers for foraging)
and “south” (migrate south to
EGoM or SNWA; Figure 11).
Both “north” and “south” are
large-scale migratory corridors
(Ceriani et al., 2012). A
resident migratory strategy was
also found and is known as
“central” (Figure 11, SAB,
central Florida coast; Ceriani et
al., 2012). Migration corridors

Figure 10. Map of the migration corridors of 14 loggerhead nesting in eastern
central Florida. (A) Pink=north, blue= south and green=resident. (B) dark pink=
summer migration and light pink=winter migrations (Ceriani et al., 2012).

in Florida allow loggerheads

Figure 11. Postnesting migratory corridors of three from three Florida rookeries, (A) northwestern rookery, (B) central
western rookery and (C) eastern rookery, PTT tracked between 1998 to 2001. Migratory corridors: yellow= eastern Florida
Panhandle southwest to Yucatán Peninsula, Mexico, red= eastern Florida panhandle southeast down coast, green= along
northern coast of Cuba, blue= southeastern Florida coast to central Atlantic Ocean (Foley et al., 2013).

efficient movement between essential nesting and foraging habitats.

21

Leatherback
Leatherbacks are the most highly migratory species of sea turtle, and due to this they
have limited migratory corridors within the area of study. Leatherbacks in the NWA DPS often
migrate though the Gulf of Mexico to the Northern Atlantic and back, cross the North Atlantic to
western Europe and Africa, and take up residence between northern and equatorial waters
(Fossette et al., 2014).
Sasso et al., (2021) found
some seasonal foraging in
the Gulf of Mexico along
the west Florida
continental shelf (NGoM
and EGoM) in autumn
and winter. Leatherbacks
migrate from the wider
Caribbean though the

Figure 12. Leatherback movements throughout Caribbean and Gulf of Mexico from 2015,
2018 and 2019. Red=foraging, blue= migration, and orange/white/light
blue=searching/foraging (Sasso et al., 2021).

Yucatan Channel to west
Florida continental shelf
at the end of summer and
return back to the wider
Caribbean at the start of
spring (Figure 12). This
migratory corridor is
primary used by
leatherbacks nesting in

Figure 13. Kernel density map of leatherback post nesting high-areas of Gulf of Mexico,
Caribbean and Northwest Atlantic (Evans et al., 2021).

22

Colombia, Honduras, Panama, and Trinidad. Another study satellite-tracked 33 leatherbacks
between 2004 to 2018 from the southwest Caribbean coast found that they used the same
migratory corridor as leatherbacks from Sasso et al. during fall and winter months (Figure
13&14; Evans et al., 2021). The Panhandle of Florida and western Florida were the primary
destinations and 55% of turtles used the migratory corridor between the wider Caribbean through
the Yucatan Channel to the Gulf of Mexico and west Florida (Evans et al., 2021). Migration
corridors in Florida allow leatherbacks efficient movement between crucial nesting and foraging
habitats.

Figure 14. Seasonal kernel density map of leatherback high-areas of Gulf of Mexico, Caribbean and Northwest Atlantic
(Evans et al., 2021).

Commercial Fishing
Commercial fishing, both current and historically, creates pressures on marine
ecosystems, with the potential for negative impacts on sea turtles. In this section the gear used by
commercial fisheries, impacts of the fishing gear, federal fishing regulations and the regulated
fishing zones within the Florida waters will be described.

Fishing Gear
There are seven main methods of fishing used by commercial fisheries (Marine
Stewardship Council [MSC], 2023). This study will be looking at five of the seven gear types,
that commonly used by the fishing industry operating within the waters of Florida that are known

23

to impact sea turtles. The five gear types are longline (pelagic and bottom), trawl (pelagic and
bottom), net, pot and trap, and dredge.

Longline
Longlining is a fishing method using lines with more than ten baited hooks that trail
behind a fishing vessel to which it is attached (MSC, 2023; FAC & FAR, 2023). Longlines can
be set at different depths of the water column, either pelagic (midwater) or bottom (near seafloor)
(MSC, 2023). Bottom longlines will have modifications to allow the line to sink to the lower
depths (MSC, 2023). Within the Atlantic Ocean, Gulf of Mexico, and Caribbean an estimated
6,444 longlines vessels were operating as of 2023 (NOAA, 2023b).

Trawling
Trawling is a fishing method using long cone-shaped nets with a closed end and open
mouth that are towed by one or two fishing vessels (MSC, 2023; FAC & FAR, 2023). Much like
longlines, trawls can also be set at different depths of the water column, either pelagic or bottom,
and net mesh size is variable depending on the target species (United States Fish and Wildlife
Service [USFWS] & Department of Interior [DOI], 2013MSC, 2023). Bottom trawls are dragged
on the seabed and due to this have alterations to increase structural support and reduce
environmental influences (USFWS & DOI, 2023; MSC, 2023; FAC & FAR, 2023). Within the
Atlantic Ocean, Gulf of Mexico, and Caribbean an estimated 13,368 trawling vessels were
operating as of 2023 (NOAA, 2023b).

Net
Netting is a fishing method in which a mesh or webbed material is deployed into the
water from a fishing vessel to catch fish (FAC & FAR, 2023). There are many different types of
nets designed to target specific species which can be set at different depths (FAC & FAR, 2023).

24

A few of the more commonly used nets are gillnets and seines. Gillnets are a “wall” of netting
hanging in the water from one or more fishing vessels and can be used in both a stationary and
moving manner (MSC, 2023; FAC & FAR, 2023). Seine nets are used to surround dense schools
of fish in a vertical “curtain-like” fashion and then either haul them onto a beach (beach seines),
or pulled closed at the bottom and hauled into vessel (purse seines) (MSC, 2023). Beach seines
are used in nearshore environments whereas purse seines are used in pelagic open ocean
environments (NOAA, 2023b; MSC, 2023; FAC & FAR, 2023). Within the Atlantic Ocean, Gulf
of Mexico, and Caribbean an estimated 16,739 netting vessels (13,590 gillnets and 3,128 seines)
were operating as of 2023 (NOAA, 2023b).

Pot and Trap
Pot and trap is a fishing method in which a stationary device, made of wood, wire netting
or plastic, is baited and deployed on the seabed attached to a rope for roughly 24 hours (FAC &
FAR, 2023; MSC, 2023). Pots and traps have a cone-shaped tunnel at the mouth to prevent target
species, various species of crustaceans, from escaping (FAC & FAR, 2023; MSC, 2023). They
are typically deployed in groups (FAC & FAR, 2023). Within the Atlantic Ocean, Gulf of
Mexico, and Caribbean an estimated 26,583 pot and trap vessels were operating as of 2023
(NOAA, 2023b).

Dredge
Dredging is a fishing method in which a net is attached a reinforced frame that drags
along the seabed while towed behind a fishing vessel (MSC, 2023). Dredges are used primarily
to harvest benthic biota, as they are designed to drag along the seabed. Due to the harsh
interactions with the seabed dredges are heavily regulated and can only be used in permitted

25

areas (MSC, 2023). Within the Atlantic Ocean, Gulf of Mexico, and Caribbean an estimated
dredge 7,403 vessels were operating as of 2023 (NOAA, 2023b).

Bycatch Impacts
Historically and presently, commercial fishing is extremely harmful to the marine
environment and its inhabitants. When looking at how fisheries have specifically impacted sea
turtles, there are multiple negative impacts, such as injury (from entanglement and/or hooks) and
mortality (from drowning and/or from severe injury). A turtle being stuck underwater for any
length of time can be lethal, as they can only hold their breath up to two hours; less if they are
active (Ripple, 1996; NOAA, 2022c). A trapped turtle is unlikely to rest, and instead be
thrashing, moving and otherwise active in an attempt to escape, decreasing its air supply and
likely causing further injury. Between 1986 to 2008 various gear regulations were put in place
for longlines, trawls, nets, pot and traps and dredges to mitigate sea turtle bycatch (Finkbeiner et
al., 2011). Prior to by bycatch mitigation methods the U.S. fisheries had an annual mean of
346,500 turtle interactions, that resulted in an estimated 71,000 annual deaths across various
species of sea turtle (Finkbeiner et al., 2011). The impact of fishing gear on sea turtles, indicates
that bycatch poses a serious threat to the health and population sustainability of loggerheads and
leatherbacks that nest, forage and migrate through Florida waters.

Longline
Longlines are a common fishing method used globally, due to their widespread presences
and ability to set in multiple depths they pose a serious threat to loggerheads and leatherbacks
(MSC, 2023; FAC & FAR, 2023). Turtles can become entangled in the line and/or gangion, or
hooked with a varying severity (Kot et al., 2010; Donoso, et al., 2010; Lewison et al., 2007;
USFWS & DOI, 2013, Ripple, 1996). Hooks severity ranges from less severe external hooking

26

(hooked on outside of body or just inside of mouth) to deep hooking (hook swallowed and is
residing internally within in throat or digestive system) (Parga, et al., 2015). It is worth noting
that external hooking often leads to the turtle entanglement in fishing line (Parga, et al., 2015;
Ripple, 1996). In the year 2000, an estimated 1.4 billion hooks were in the water daily and thus
resulting in the bycatch of an estimated 200,000 loggerheads and 50,000 leatherbacks, with 37%
of the bycatch from fisheries operating in the Atlantic Ocean (Lewison et al. 2004). A study of a
longline fishery in Chile, between 2001 and 2005, reported bycatch of 284 and 59 leatherbacks
and loggerhead, respectively, from over 10 million hooks (Donoso et al., 2010). Lastly, a study
of Atlantic longline fisheries sea turtle bycatch between 1986 to 2009 found a total of 6,832 sea
turtles caught in longline gear between the regions on Figure 15, with a total annual bycatch of
297 turtles (Kot et al., 2010). Of those 6,832, 51% (n=3,514) were loggerheads and 41%
(n=2,844) were
leatherbacks, the results
in an estimated average
annual bycatch of 152.9
and 123.6 respectively
(Kot et al., 2010). Prior
to regulations, the
Atlantic and Gulf of
Mexico pelagic longline
fishery had an estimated
annual mean of 1800 and
150 sea turtle interactions

Figure 15. NOAA SEFSC Atlantic longline fishing regions and NOAA longline marine
managed areas between 1986 to 2009 (Kot et al., 2010). Caribbean (CAR), Gulf of
Mexico (GOM), Florida East Coast (FEC), South Atlantic Blight (SAB), Mid Atlantic
Blight (MAB), Northeast Coastal (NEC), Northeast Distant (NED, North Central
Atlantic, (NCA) Tuna North (TUN) and Tuna South (TUS).

27

and deaths, respectively (Finkbeiner et al., 2011). Longlines therefore pose threats to sea turtles
as they account for a sizable amount of bycatch.

Trawl
Like longlines, trawls also pose a threat to loggerheads and leatherbacks due to their
widespread presence and ability to be set at multiple depths (Finkbeiner et al., 2011; FAC &
FAR, 2023; MSC, 2023). Trawls can catch turtles within their nets leading to entrapment and
engagement, which can, and often does, result in injury or mortality (Robins, 1995; Epperly, et
al., 2002). In a study of the Queensland East Coast Otter Trawl Fisheries penaeid prawn trawlers,
done between 1991 to 1992, the annual sea turtle bycatch rate was 325.5 turtles with a 1.1%
(n=3.5) mortality rate, with 50.4% (n=164) being loggerheads (Robins, 1995). A 2004 to 2005
study on Mid-Atlantic scallop trawl fisheries (4,433 vessel trips) had an estimated annual
bycatch range of between 81 to 191 turtles per year (Murray, 2007). A 1987 study of U. S.
shrimp trawl fishers reported a bycatch total of 534 sea turtles (loggerhead, Kemp's ridley
[Lepidochelys kempii], and green [Chelonia mydas] turtles), 482 from the Atlantic and 52 from
the Gulf of Mexico, with a 20% mortality rate (Henwood et al., 1987). Using this data and
population estimates from the time, Henwood, et al. estimated that 9874 loggerheads died
annually due to U. S. shrimp trawl fishers (Henwood et al., 1987). Prior to regulations on trawls,
98% of sea turtle bycatch was from the Southeast Atlantic and Gulf of Mexico Shrimp Trawl
fisheries, with an estimated 340,500 and 69,300 sea turtle interactions and deaths, respectively
(Finkbeiner et al., 2011). These studies all show that trawls have high rates of bycatch and
mortality.

28

Pot and Trap
Pot and Trap bycatch of sea turtles is a relatively unresearched area. Much like longlines,
the vertical lines on each trap and pot are a source of entanglement for the sea turtles, which
could result in the turtle’s injury or death (Zollett, 2009). It is uncertain whether loggerheads or
leatherbacks are more commonly entangled with these vertical trap lines (Zollett, 2009).
Loggerheads diet of benthic biota such as crustaceans, which is the target species of pots and
traps, lead some researchers to believe they would more easily be caught in pot and trap lines
(Zollett, 2009; Avissar, 2006; Hamelin et al., 2017). A 2005 study on pot and trap damage,
conducted on North Carolina's blue crab fishery, showed that 82% of pots/traps (100 pots/day
over 41 days) had evidence of loggerhead damage (Avissar, 2006). On the other hand,
leatherbacks could become entangled in the lines while foraging in their pelagic environment
(Zollett, 2009). One study found that between 1998 to 2004, there were 205 leatherback
interactions with pot and trap gear, with an 89.9% survival rate (Hamelin et al., 2017). This
limited research does not allow for a conclusion to be drawn on the severity of the pot and trap
bycatch. With evidence of some turtle bycatch, and as the pot and trap is the largest fishery
within the Gulf of Mexico and Atlantic, pot and trap were included as a gear of study.

Net
Net gear from fishers are known to entangle sea turtles which can lead to injury and death
(Finkbeiner et al., 2011; Murray, 2009b). Although many types of nets are used in fishing, I
focused on gillnets and seine nets as they are the most commonly used nets in the waters around
Florida (NOAA, 2023). A study of US mid-Atlantic gillnet fisheries, between 1995 to 2006,
demonstrated an estimated annual mean bycatch of 350 loggerheads, in which there was a 40%
mortality rate (Murray, 2009b). Gillnets with shorter mean soak times (the time that the nets are
left in the water, in this study) (29.6 hours), and smaller mesh (<17.8cm) had lower mortality

29

rates then gillnets with longer mean soak times of (80 hours) and larger mesh. (Murray, 2009b).
Prior to regulations, net fisheries in the Atlantic and Gulf of Mexico had an estimated annual
mean of 1,310 and 250 sea turtle interactions and deaths, respectively, with gillnets accounting
for 510 and 240 of those interactions and deaths (Finkbeiner et al., 2011).
A 16-year study on the European purse seine fisheries of the Atlantic and Indian oceans
found that they had lower impacts on sea turtles. Over the course of the study the total bycatch
was 597 turtles, which is 37.3 turtles annually between both the Atlantic and Indian oceans
(Bourjea et al., 2014). Of these 597 turtles, 92 were loggerheads (6 dead and 6 unknown) and 69
leatherbacks (4 dead and 3 unknown) combined count from both oceans (Bourjea et al., 2014).
This means that the annual bycatch and mortalities counts are 5.75 and 0.375, respectively, for
loggerheads; and for leatherbacks are 4.31 and 0.25, respectively (Bourjea et al., 2014). These
studies show that the impacts of nets on sea turtles are highly variable, and depended upon the
net and its use, with gillnets having significantly higher amounts of bycatch than purse seine.

Dredge
Dredging is not as common the other fishing types, but despite the reduction in use,
dredges still pose a threat to sea turtles as they risk entrapment and engagement within the
dredge net, which can lead to injury or death. The limited use of dredging in the commercial
fishing industry has resulted in limited research on this gear type. One study in the Mid-Atlantic
estimated an annual mean of 90 and 68 sea turtle interactions and deaths and serious injuries due
to dredges, respectively (Finkbeiner et al., 2011). This resulted in dredges having the fifth
highest mean annual loggerhead mortality and serious injuries according to that study
(Finkbeiner et al., 2011). Another study between 1980 and 2003 reported the bycatch of 508 sea
turtles within the Atlantic and Gulf of Mexico, 115 being loggerhead sea turtles (Dickerson et

30

al., 2004). These studies show that dredges do threaten sea turtles, with a disproportionately high
risk of bycatch causing death or serious injury.

Regulations
In order to protect the marine environment and ensure longevity of the fishing industry,
fishing regulations have been created. Regulations requiring bycatch mitigation methods allowed
for an estimated 60% (from 346,500 to 137,800) and a 94% (from 71,000 to 4,600) reduction in
sea turtle interactions and mortality, respectively (Finkbeiner et al., 2011). These regulations are
extensive; thus, I will only cover regulations put in place to protect the sea turtle within the Gulf
of Mexico, Caribbean, and/or South Atlantic regions.

Federal
Title 50, part 622 created by the U.S. Fish and Wildlife Service & Department of Interior
and updated in 2013, outlines the federal fishing regions of for the Gulf of Mexico, Caribbean,
and/or South Atlantic regions. Herein I shall discuss the general prohibited fishing practices.
Fishing has seasons and/or area closures that strictly prohibit or limit fishing, and this includes
areas with seasonal/permanent gear closures as well. Catching protected species, such as sea
turtles, is also prohibited. Various fishing gear and methods have been found to have heath
and/or environmental impacts and thus have been banned as well. Prohibited gear includes
explosives, certain fish traps, an absence of weak links in the tickler chains, and using Gulf reef
fish as bait (USFWS &DOI, 2013) These general regulations protect the marine environment as
a whole.
Three main regulations are sea turtle specific, according to Title 50. These regulations
regard turtle excluder devices (TED) for trawlers, sea turtle bycatch mitigation for longlines and
lastly, checks and in water durations of gillnets (USFWS & DOI, 2013).

31

Trawlers within the Atlantic area or Gulf area must have an approved TED. A TED is a
device made of metal bars and mesh placed inside of a fishing trawl’s neck; this allows the target
species to pass through the bags into the net while allowing turtles or other larger species to be
kept out of the net, thus reducing bycatch in trawling industries (NOAA, 2021; USFWS & DOI,
2013). A study conducted on beaches in South Carolina between 1980 to 1993 on loggerheads
found that prior to the use of TEDs there was a 5.3% per year population decline (Crowder et al.,
1995). Before TEDs were required, 70% to 80% stranding mortalities were attributed to shrimp
trawls (Crowder et al., 1995). As of April 1, 2021, a new rule regarding TEDs was enacted by
the National Marine Fisheries Service (NMFS): “all skimmer trawl vessels 40 feet and greater in
length to use TEDs designed to exclude small sea turtles in their net” (NOAA, 2021). After the
implementation of TEDs, the SE Atlantic and Gulf of Mexico Shrimp Trawl experienced an
estimated reduction of 207,100 and 65,600 turtle interactions and deaths annually, from 340,500
to 133,400 interactions and 69,300 to 3700 deaths annually (Finkbeiner et al., 2011). The uses of
TEDs allow the turtles to escape the trawl net, thus reducing bycatch and turtle injury/mortality.
Longlines, both pelagic and bottom, within the Atlantic area or Gulf area are required to
use sea turtle bycatch mitigation gear and keep the NMFS document “Careful Release Protocols
for Sea Turtle Release with Minimal Injury,” on board the vessel, as well as have gear
modifications designed to protect turtles (USFWS & DOI, 2013). Bycatch mitigation gear is gear
used to unhook/detangle turtles from the longlines. This gear consists of long-handled line
clipper/cutter (for cutting line), long-handled dehooker (for removal of ingested or external
hooks), dipnet (a net used to bring a turtle onboard the vessel), tire (for keeping turtle in upright
orientation), short-handled dehooker (for removal of ingested or external hooks), long-handled
device (for “inverted V.”- dehooking technique), long-nose or needle-nose pliers (for embedded

32

hook removal, bolt cutters (to cut hooks to help with removal), monofilament line cutters ( to cut
lines of swallowed/unremovable hooks), turtle control devices (tether or T&G ninja sticks used
to keep turtle still and at side of vessel to allow for hook removal/entanglement) and mouth
openers (to open turtles mouth for hook removal) (USFWS & DOI, 2013). Requiring gear for
unhooking and detangling turtles will reduce injury severity and allow for higher post catch
survival rates.
The NMFS document provides a protocol on how to care for and release sea turtles
caught in longlines. This document goes over the when/when not to bring turtles onboard a
longlining vessel for hook removal; turtle are to be “boated” (brought on board using a dipnet) if
they are of a size and/or are hooked in a manner in which would cause minimum injury, where as
“non-boated” turtles would be those that are too large and/or boarding cannot be done without
further injuring the turtle (USFWS & DOI, 2013). Having protocols for how to handle the turtle
further ensures their proper treatment and reduces possible injury and mortality.
Lastly gear modifications that are required to be made for all longlines are Gangion (short
line off longline holding hooks) length, bait and hook size/type. Gangion are a contributor to
turtle entanglement in longlines fisheries (Lewison et al., 2007; USFWS & DOI, 2013). Only
whole finfish and/or squid bait is allowed to be used on longlines, unless a green-gear stick (line
with 10 hooks/ gangions attached suspended above the surface of the water) is used and then
artificial bait may be used (USFWS & DOI, 2013). Studies have found reduced hard-shelled
turtles (such as loggerheads) and leatherback bycatch when fish and/or squid was used, and this
also reduced the amount of deep hooking (Gilman et al., 2017). Circle hooks are to be used on
all longlines; these hooks can be offset or non-offset. Non-offset circle hooks utilize a size a
minimum of 16/0 with the widest point of hook no smaller than 1.74 inches. Offset hook size

33

utilizes a minimum of 18/0 with the widest point of hook no smaller than 2.16 inches, and the
offset can be no larger than 10° (USFWS & DOI, 2013). In the 2019 and 2020 nesting season
fishing hooks accounted for 7% of all injuries sustained by loggerheads in southwestern Florida
(Ataman, et al., 2021). Hard-shelled turtles (such as loggerheads) and leatherback bycatch rates
are lower using wide circle hooks rather than other hooks, such as J-shaped hooks, and reduced
the number of deep/ingested hooks of hard-shelled turtled (Gilman et al., 2017). A study
conducted between 2000 and 2004 in the western North Atlantic, the Azores, the Gulf of
Mexico, and Ecuador found that use of circle hooks reduced sea turtle mortality due to their
shape and size (Read, 2007). Using gear proven to reduce bycatch further reduces bycatch in
longlines, thus showing the bycatch mitigation regulations benefits.
Drift gillnets must be checked at minimum every two hours and sink gillnets soak time
(time in water) cannot exceed 24 hours. A 2009 study found that 285 loggerheads are caught in
the Mid-Atlantic sink gillnet fishery, with engagement in the anchor gear being the most
common (Murray, 2009a; Murray, 2009b). Between 1990 to 2017, a total of 302 turtles were
caught by drift gillnets, with n=100 loggerhead and n=169 leatherbacks (Carretta et al., 2019).
Sea turtles require air to breath and can only go without for 2 hours while in rest and a few
minutes while active (NOAA, 2022c; Ripple, 1996). As turtles will drown if unable to get to the
surface for extended periods of time, requiring check time for gillnets will prevent sea turtle
bycatch morality (Ripple, 1996). After the implementation of these regulations on gillnets, the
Atlantic and Gulf of Mexico experienced an estimated reduction of 100 and 100 sea turtle
interactions and deaths annually, from 510 to 410 interactions, and 240 to 140 deaths annually,
respectively (Finkbeiner et al., 2011).

34

State
States must follow federal fishing regulations, however, they may also add additional
regulations. In Florida four fishing regulations were added and are enforced within the range of
the state waters, according to Florida Regulations (FAC & FAR, 2023; Florida Legislature,
2023). These regulations regard monofilament line and netting, longlines, and net gear
specifications (FAC & FAR, 2023). The intentional discard of monofilament line and netting
within state waters is prohibited (FAC & FAR, 2023). Monofilament line and netting must be
disposed of on land. The recovery of monofilament line and netting from state waters is also
prohibited if the Division of Law Enforcement has not been notified and is not present (FAC &
FAR, 2023). As of January 1, 1993, the use of longline within state waters is prohibited, except
for when they are in transit to or from the EEZ (FAC & FAR, 2023). The use of gillnet,
entangling nets, nets larger then 500 square feet are prohibited within state waters and only one
net can be placed at once, with soak times no longer than one hour (Florida Legislature, 2023;
FAC & FAR, 2023). Additionally, within nearshore/inshore areas cast nets cannot exceed 14 feet
stretched length (FAC & FAR, 2023). State regulations protect sea turtles in the Atlantic and
Gulf of Mexico and help reduce bycatch of these endangered species.

Regulated Fishing Zones
The coastal waters of Florida of consist of two different bodies of water, the Gulf of
Mexico and the Atlantic Ocean. Within a 100 nautical mile radius of Florida coast (area of
study) there are 51 separate regulated fishing zones: The Atlantic Ocean has 34 zones (Table 2),
and the Gulf of Mexico has 17 zones (Table 3). Of the 51 zones, 45 allow commercial fishing,
and 6 do not allow any fishing. The names and details of the fishing regulations (fishing
allowances, gear restrictions and fishing/gear seasons), along with a count of the number of gear

35

restrictions, is detailed in Tables 2 and 3 (U.S. Fish and Wildlife Service & Department of
Interior, 2013).

Conclusion
Sea turtles face threats to survival in the waters off the Florida coast, and the prevalence
of commercial fishing further raises these risks. Gear from the widespread commercial fishing
industry in Florida impacts the turtle’s ability to thrive and is a large part the cause of why these
species are still struggling. Trawls and longlines are among the most prevalent gear used in this
region and has been shown to negatively harm or kill the sea turtles. Federal regulations
regarding bycatch mitigation methods can only protect sea turtles after they have interacted with
fishing gear. As loggerheads and leatherbacks use Florida as foraging, nesting, and breeding
grounds as well as a migratory corridor, the use of commercial fishing gear disrupts the turtles
and can result in their death. Understanding the movements of sea turtles with the Gulf of
Mexico and Atlantic waters surrounding Florida would allow for these interactions to be further
mitigated.

36

Table 2. Fishing zones and their regulations within 100 nautical mile radius of Florida coast in the Atlantic Ocean. Yes=
allowed, No= not allowed and Never= zone is not open to any fishing/gear ever. (U.S. Fish and Wildlife Service & Department
of Interior, 2013).
Atlantic
Fishing Zones

Fishing
Allowed

Stetson-Miami
Terrace HAPC

Yes

Artificial Reef-A

Yes

Artificial Reef-ALT

Yes

Artificial Reef-C

Yes

Artificial Reef-CAT

Yes

Artificial Reef-CCA

Yes

Artificial Reef-DRH

Yes

Artificial Reef-DUA

Yes

Artificial Reef-F

Yes

Artificial Reef-G

Yes

Artificial Reef-J

Yes

Artificial Reef-KBY

Yes

Artificial Reef-KC

Yes

Artificial Reef-KTK

Yes

Artificial Reef-L

Yes

Artificial Reef-MRY

Yes

Artificial Reef-SAV

Yes

Artificial Reef-SFC

Yes

Eagles Nest Reef

Yes

Ft. Pierce Inshore
Reef
Ft. Pierce Offshore
Reef
Key
Biscayne/Artificial
Reef-H
Florida Keys
National Marine
Sanctuary
Pourtales Terrace
HAPC
Oculina Bank HAPC
Oculina Bank
Experimental Closed
Area
Allowable Octocoral
Closed Area

Yes
Yes

Fishing
Months
Open
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround

Longline
Pelagic

Trawl
Net

Dredge

Pot &
Trap

Bottom

Pelagic

Bottom

Yes

No

No

No

Yes

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

Yes

No

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Yes

Gear
Months
Allowed
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround

Counts
Gear
Restrict.
5
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
1
1
1

Yes

Yearround

Yes

No

Yes

Yes

Yes

Yes

Yes

Yearround

1

No

Never

No

No

No

No

No

No

No

Never

7

Yes

No

No

No

Yes

No

No

Yes

No

Yes

No

Yes

No

No

Yes
Yes

Yearround
Yearround

Yearround
Yearround

5
4

Yes

Yearround

Yes

No

Yes

No

Yes

No

No

Yearround

4

Yes

Yearround

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yearround

0

Table 2 continued on next page

37

Table 2 continued.
Atlantic
Fishing Zones

Fishing
Allowed

East Hump

Yes

North Florida

Yes

St. Lucie Hump

Yes

Longline Prohibited
North of 27 10'N
Longline Prohibited
South of 27 10'N

Yes
Yes

East Florida Coast

Yes

Charleston Bump
closed area

Yes

Atlantic Unregulated

Yes

Fishing
Months
Open
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround

Longline

Trawl
Net

Pelagic

Dredge

Pot &
Trap

Gear
Months
Allowed

Counts
Gear
Restrict.

Bottom

Pelagic

Bottom

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

No

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Yes

Yes

Feb- Apr

1

Yes

YearRound

0

Yes

Yes

Yes

Yes

Yes

Yes

Yearround
Yearround
Yearround
Yearround
Yearround
Yearround

7
7
7
2
2
1

Table 3. Fishing zones and their regulations within 100 nautical mile radius of Florida coast in the Gulf of Mexico. Yes=
allowed, No= not allowed and Never= zone is not open to any fishing/gear ever (U.S. Fish and Wildlife Service & Department of
Interior, 2013).
Gulf of Mexico
Fishing Zones
The Edges
Madison and Swanson
Marine Reserve
Steamboat Lumps
Marine Reserve

Fishing
Allowed

Fishing
Open
Season

Pelagic

Bottom

Pelagic

Bottom

No

Never

No

No

No

No

No

No

No

Never

7

No

Never

No

No

No

No

No

No

No

Never

7

No

Never

No

No

No

No

No

No

No

Never

7

Middle Grounds HAPC

Yes

Pully Ridge HAPC

Yes

Reef Fish Longline
Restriction
Reef Fish Stressed
Areas, FL, AL and MS
Reef Fish Stressed
Areas, FL West Coast
Bottom Longline
Prohibited
SW Florida Trawl
Closure
Tortugas Shrimp
Sanctuary South
Tortugas Shrimp
Sanctuary North
Tortugas Shrimp
Sanctuary Zone FQUT
Tortugas Shrimp
Sanctuary Zone TUVW
Tortugas Shrimp
Sanctuary Zone GVW
Tortugas Marine
Reserve South
Tortugas Marine
Reserve North
Gulf of Mexico
Unregulated

Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes

Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround
Yearround

Longline

Trawl

Net

Dredge

Pot &
Trap

Gear
Allowed
Seasons

Yearround
Yearround
Yearround
Yearround
Yearround
JunSept
Yearround
Yearround
Yearround
AugMar

Counts
Gear
Restrict

Yes

No

Yes

No

Yes

No

No

4

Yes

No

Yes

No

Yes

No

No

No

No

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Oct- Apr

2

Yes

Yes

No

No

Yes

Yes

Yes

Aug-Apr

2

7
2
1
1
1
2
2
2
2

No

Never

No

No

No

No

No

No

No

Never

7

No

Never

No

No

No

No

No

No

No

Never

7

Yes

Yearround

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yearround

0

38

Methods
Data Collection
Study Area
For this study, fishing
regions and turtle relocations
within 100 nautical miles of
the coast of Florida were
examined. Florida’s coastal
waters are split between two
separate water bodies, the
Gulf of Mexico on the West
side of the peninsula and the

Figure 16. Study area and USA EEZ, 100 nautical miles of Florida Coast.

Atlantic Ocean on the East side (Figure 16). The border of Atlantic and Gulf of Mexico is
located at the southern tip of Florida and extending South. Florida state waters in the Atlantic
and Gulf of Mexico are from the shore to 3 nautical miles on the Atlantic and from shore to 9
nautical miles in the Gulf of Mexico, with the federal waters extending 200 nautical miles from
the ends of the state waters (NOAA, 2023b).

Species of Study
Satellite movement (known as relocations) of loggerhead (Caretta caretta) and
leatherback (Dermochelys coriacea) sea turtles were provided by The Sea Turtle Conservancy. A
total of 45 female individuals were tracked, 34 loggerheads 2009 to 2017 and 11 leatherbacks
from 2005 to 2017. Location in which relocation tracking began was not provided by The Sea
Turtle Conservancy, only relocations within 100 nautical miles of the coast of Florida were
provided.

39

Individual relocations were tracked using Platform Terminal Transmitters (PTT) that are
attached to the turtle carapace and transmit location data to the satellite when the turtle surfaces
(Sea Turtle Conservancy, n.d.). The satellites make on average 8 rotations around the planet per
day giving a 10-minute window per day for the data to be collected. This must also coincide with
the turtle surfacing which can allow for high location variations upon each location transmission
(Sea Turtle Conservancy, n.d.). The accuracy of the PTT has an average error variation between
50 meters to 2.5 kilometers depending on the number of satellites in the area (Sea Turtle
Conservancy, n.d.).

Regulated Fishing Zones and Commercial Fishing Gear Regulations
There were 52 regulated fishing zones between the Atlantic (35) and Gulf of Mexico
(17), all zone data was pulled from 50 CFR Part 622 -- Fisheries of the Caribbean, Gulf of
Mexico, and South Atlantic (Figure
17; Tables 2&3; U.S. Fish and
Wildlife Service & Department of
Interior, 2013). Only fishing zones
with an area of 450mi2 and 3 or
more kernel density (mean,
median, maximum, and standard
deviation) and results  0. Of the
52 zones, a total of 19 zones met
these criteria and were considered

Figure 17. Regulated fishing zones in the Atlantic and Gulf of Mexico up to 100
nautical miles off Florida coastline.

40

Figure 18. Analyzed Gulf of Mexico Zones.

as potential bycatch risk, 10 in the
Atlantic and 9 in the Gulf of Mexico
(Figure 18&19). An area minimum was
established to reduce the results being
leveraged into smaller zones (see
discussion for more information). Within
the regulated fishing zones 7 commercial
fishing gear regulations were analyzed,
longline (pelagic and bottom), trawl
(pelagic and bottom), pot and trap, net,
and dredge. See literature

41

view for further background on each of the gear types. Each of the gear types were checked for
usage regulations in each of the zones (Tables 4&5).
Table 4. Gear restrictions of Atlantic regulated fishing zones. Yes= allowed, No= not allowed.

Atlantic
Figure
19. Analyzed Atlantic regulated fishing zones.
Longline

Trawl

Zone

Net
Pelagic

Bottom

Pelagic

Dredge

Pot &
Trap

Bottom

Unregulated Atlantic

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Stetson-Miami Terrace HAPC

Yes

No

No

No

Yes

No

No

Charleston Bump closed area

No

Yes

Yes

Yes

Yes

Yes

Yes

Allowable Octocoral Closed Area

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Pourtales Terrace HAPC

Yes

No

No

No

Yes

No

No

East Florida Coast

No

Yes

Yes

Yes

Yes

Yes

Yes

Longline Prohibited South of 27 10'N

No

No

Yes

Yes

Yes

Yes

Yes

Longline Prohibited North of 27 10'N

No

No

Yes

Yes

Yes

Yes

Yes

FKNMS

No

No

No

No

No

No

No

Yes

No

Yes

No

Yes

No

No

Oculina Bank HAPC

Table 5. Gear restrictions of Gulf of Mexico regulated fishing zones. Yes= allowed, No= not allowed.

Gulf of Mexico
Longline

Trawl

Zone

Net

Dredge

Pot &
Trap

Pelagic

Bottom

Pelagic

Bottom

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

Yes

Yes

Yes

No

No

Yes

Yes

Yes

Tortugas Shrimp Sanctuary North

No

No

No

No

No

No

No

Middle Grounds HAPC
Reef Fish Stressed Areas, FL, AL
and MS
The Edges

Yes

No

Yes

No

Yes

No

No

Yes

Yes

Yes

No

Yes

Yes

Yes

No

No

No

No

No

No

No

Unregulated-Gulf of Mexico
Reef Fish Longline Restriction
Bottom Longline Prohibited
Reef Fish Stressed Areas, FL
West Coast
SW Florida Trawl Closure

Geospatial Analysis
ArcGIS software by ESRI was used to create a series of maps both detailing the
movements of turtles during the duration of the study period and in regulated zones. The relative

42

density of turtle relocations in the study area was then calculated using the Kernel Density
function. This allowed me to see where the turtles were more likely to be (and when), and the
regulations in each of these zones

Fishing Zone Maps
The zone maps were created on ArcGIS using outline the regulated and unregulated
fishery zones up to 100 nautical miles off the Florida coast, in both the Atlantic Ocean and Gulf
of Mexico. The regulated zone maps used pre-created shape files pulled from NOAA (NOAA,
2023b). Each of the regulated zone’s attribute tables contain information regarding gear
regulations, fishing allowances, and yearly timelines of open fishing and gear seasons. The
unregulated zones were created by making a 100 nautical mile radius off the coastline of Florida
and then using the clipping tool to remove all the regulated zone polygons and areas that overlap
with land. All Zone maps were split into 2 groups based on what ocean they reside in, Atlantic or
Gulf of Mexico. This is due to general regulations that govern each of the bodies of water.

Sea Turtle Maps
The sea turtle relocation maps consist of two separate maps for each species (leatherback
and loggerhead) created on ArcGIS using coordinate, timestamp and PTT number data provided
by the Sea Turtle Conservancy. The coordinates where of each location the in which the PTT tag
had been detected when the turtle surfaced as the satellites where overhead, which meant the
coordinate data of the turtles’ movements were not fully encompassing, but rather a snapshot of
their movement during the period of observation. Every turtle had a unique PTT tag number
associated with it. Using the coordinates of each turtle’s points were established on the map at
each relocation, then a pattern of movement was found by connecting each re-location point to
the next re-location point with the next chronological timestamped point for each individual

43

turtle. This was repeated for each turtle for both the loggerheads (n= 34) and leatherbacks (n=
11) for the duration of tracking.
Sea turtles tend to be
a highly migratory species,
thus no single turtle stayed in
the area of study (100
nautical miles off the coast
of Florida) all of the time.
The time of year with the
most relocations for both
leatherbacks and loggerheads
coincided with their nesting
Figure 21. Loggerhead relocations between 2009 to 2017 (n=34 individual turtles).

season (Figures 20&21.
Florida is a vital nesting
ground for both species and
these data corroborate the
increase in activity during
this timeframe (NOAA,
2023a). Loggerheads’
nesting season is June to
September while
leatherbacks’ is May to
September (United States &

Figure 20. Leatherback relocations between 2005 to 2017 (n=11 individual turtles).

44

National Marine Fisheries Service, 2013; TEWG; 2007). To account for the increased activity of
turtles migrating into and out of this region for nesting season, a 1-month buffer was added to the
start and end of both species nesting season. For the purpose of this study, the nesting season for
loggerheads and leatherbacks were reported as May to October and July to October, respectively.
These seasons were then combined for the duration of tracking, 9 years for loggerheads (2009 to
2017) and 12 years for leatherbacks (2005 to 2017), on the maps reflecting each species.

Kernel Density
Once the nesting season maps for both leatherback and loggerhead turtles were created,
the Kernel density (KD) tool on ArcGIS was used to determine the relative density of each
species in the coastal waters of Florida (ESRI, n.d.) (Figure 21). To determine the KD of each
species, the cell output was set to 0.1, area units in SQ KM and land features were removed by
using the barrier tool in order to create a more realistic distribution of KD values. This allowed
for hotspots of the loggerhead and leatherback densities to be identified.

Figure 22. Expanded kernel density (ESRI, n.d.).

Statistical Analysis
Zonal Statistics
The Zonal Statistics as Table (Spatial Analyst) was used to create the mean, median,
maximum and standard deviation (SD) from the KD raster in each of the fishing zones as well as
the unregulated Gulf of Mexico and South Atlantic zones. Although these statistics were
calculated for all fishing zones, in the results only those for zones > 450mi2 are presented to
avoid spurious findings by chance alone for small zones that might overlap KD hotspots.

45

Analysis
The risks of commercial fishing gear on sea turtles were analyzed at four main points, 1)
prevalence of gear restrictions (total and gear type) from all regulated zones, 2) turtle relocation
KD of each zone 3) the relationship between count of gear regulations and zone turtle relocation
KD, 4) the relationship gear type regulations and zone turtle relocation KD. These points allow
me to analyze the risk for loggerheads and leatherbacks that reside in the Florida coastal waters
during their nesting seasons.
The prevalence of gear restrictions from all zones was looked at in two parts: the total
number of gear restrictions, and the types of gear restrictions. Simple counts of total gear and
gear type were taken from each of the 50 regulated fishing zones. Counts of total gear
restrictions were compared by zone to determine which zones had the highest/lowest restrictions.
Similarly types of gear restrictions were compared to determine which gear types had the
highest/lowest gear restrictions. This created a baseline for points 2 and 3 to allow a better
understanding of all the gear restrictions in the Atlantic and Gulf of Mexico that can impact
loggerheads and leatherbacks.
Turtle relocation KD of each zone was determined by the zonal statistics (mean median,
maximum, and SD) as well as considering zone area (mi2). These statistics were examined and
compared with the hotspot maps to determine which zones are more commonly used by turtles
than others. Median and mean were used to find the overall KD of the zone. Determination of the
maximum found the highest KD values in each zone, which allowed for the higher value KD
hotspots residing in the zones to be identified. Standard deviations were used to determine the
variation of KD throughout the zone, which helped determine the prevalence of hotspots within
the zones. Area was considered with SD as larger zones typically had higher SD than smaller

46

zones. Together these results allowed me to determine where turtles are most prevalent in the
Florida coastal waters. This was repeated for both sea turtle species.
`

The relationship between count of gear regulations and zone turtle relocation KD was

found by comparing each zone’s gear counts with the median KD. Linear regressions and R2
were used to determine if there were a positive, negative or null relationship between the zone
turtle relocation KD of loggerheads and leatherbacks with the count of gear restrictions (Figure
23 &24).

Figure 23. Expanded R 2 equation.

Figure 24. Linear regression equation.

The relationship gear type regulations and zone turtle relocation KD was concluded by
examining the zones with higher (0) KD with lower (<0) KD. Here, bar charts were created to
visually view which zones with higher KD were associated with higher gear restrictions of any
of the gear types. T-tests were used to determine if there was an association between higher gear
types and higher KD.

47

Results
Gear Restrictions
Between the Atlantic and Gulf of Mexico, 51 zones have commercial fishing gear
restrictions of the five gear types (longline, pot and trap, net, dredge, and trawl) that have been
found to be the detrimental to loggerhead and leatherback sea turtles. Analyzing the regulations
of each of these zones allowed determination of the gear allowances in each zone (and what gear
types have more allowances), in each region of the Florida coastal waters.

Zonal Gear Restrictions
Atlantic
In the Atlantic, 2 zones (5%), the Allowable Octocoral Closed Area and the Unregulated
Atlantic, have the least amount of gear restrictions, with no (types=0) gear restrictions (Table 2).
21 zones (60%) have the most gear restrictions, with all 7 gear types restricted (Table 2). The
Allowable Octocoral Closed Area and the Unregulated Atlantic zones both have allowances for
all five gear types, and no restrictions on where the longlines or trawls can be used in the water
column (pelagic or bottom). The 21 zones with the most restrictions had regulations on all 7 gear
types. Out of the 35 regulated fishing zones in the Atlantic, there only 14 zones (40%) with gear
allowances of one or more of the 7 fishing gear types, and 9 zones (25.7%) have gear allowances
counts of ≥ 3.5 or half of all gear types (Table 2).

Gulf of Mexico
In the Gulf of Mexico, the Gulf of Mexico Unregulated zone has the lowest count of gear
regulations (type=0), whereas 5 zones (27%) (The Edges, Madison and Swanson Marine
Reserve, Steamboat Lumps Marine Reserve, and Tortugas Marine Reserve North and South) are
share the most restrictions (type=7) (Table 3). The Gulf of Mexico Unregulated zone has no gear
restrictions for all five gear types, and no resections on where the longlines or trawls can be used

48

in the water column (pelagic or bottom). Out of the 18 regulated fishing zones, 13 zones (72%)
have allowances for gear usages, were 11 zones (61%) have gear allowances counts of ≥ 3.5 or
half of all gear types (Table 3).

Gear Type Restrictions
Between both the Atlantic and Gulf of Mexico, Trawl and longline restrictions were the
most common, together making up 62% of all gear restrictions (Figure 25). Trawls had the most
restrictions, a total of 31% of all gear restrictions between both pelagic (14%) and bottom (17%)
(counts: pelagic=34, bottom=40 and total= 74). Longlines had the second most gear restrictions,
a total of 31% of all gear restrictions between both pelagic (13%) and bottom (17%) (counts:
pelagic=31, bottom=40 and total= 71). Trawls and longlines’ pelagic and bottom breakdown had
higher gear counts then dredges 14% (count= 32), nets 11% (count=26) and pot and traps 14%
(counts=32) (Figure 25). The exception to this is the pelagic longlines, which have the second
lowest number of restrictions. Nets have the lowest number of restrictions between both the
Atlantic and Gulf of Mexico (Figure 25).
COUNTS OF GEAR TYPE RESTRICTIONS: ATLANTIC & GULF OF
MEXICO
80

74

71

70

COUNT

60
50
40

40
31

40

34

26

30

32

32

DREDGE

POT &
TRAP

20
10
0
LONGLINE: LONGLINE: LONGLINE TRAWL:
PELADGIC BOTTOM
TOTAL
PELADGIC

TRAWL:
BOTTOM

TRAWL
TOTAL

NET

GEAR TYPE
Figure 25. Counts of restrictions in both the Gulf of Mexico and Atlantic Ocean by gear type.

49

Atlantic
In the Atlantic there is a total of 175 gear restrictions between all 35 regulated fishing
zones. The most restricted gear type throughout all the zones was longlining making up 32% of
all gear restrictions between both pelagic and bottom longlining, pelagic=25 (14%), bottom=31
(18%) and total=56 (32%), whereas the least restricted gear type was netting, net=21 (12%)
(Figure 26). Trawls were the second most restricted gear making up 27% (counts: pelagic=23
(13%), bottom=35 (14%) and total=48 (27%)). Pot and trapping and dredging were tied for third
with each having 25 (14%) gear restrictions. Longlines were used over 2 times more than pot and
traps, dredges, and nets. Looking at just pelagic and bottom breakdown longline and trawls
amount of gear restrictions, Pelagic trawls have the second lowest, bottom trawls and pelagic
longlines are tied for third with pot and traps and dredges, and bottom longlines have the most
gear restrictions (Figure 26). Overall, longlines and trawls were the most commonly restricted
gear types.
COUNTS OF GEAR TYPE RESTRICTIONS: ATLANTIC
70
56

60

48

50

COUNTS

40
30

31
25

23

25

TRAWL:
PELAGIC

TRAWL:
BOTTOM

21

25

25

DREDGE

POT &
TRAP

20

10
0
LONGLINE: LONGLINE: LONGLINE
PELAGIC
BOTTOM
TOTAL

TRAWL
TOTAL

NET

GEAR TYPES
Figure 26. Counts of restrictions in the Atlantic by gear type.

Gulf of Mexico
In the Gulf of Mexico there is a total of 101 gear restrictions between all 18 regulated
fishing zones. The most restricted gear type throughout all the zones were trawling, making up
43% of all gear restrictions between both pelagic and bottom trawls (counts: pelagic= 11 (18%),
bottom=15 (25%) and total=26 (43%)), whereas netting had the least gear restrictions making up

50

8% (count=5) (Figure 27).Longlines have the second most restrictions (counts: pelagic=6 (10%),
bottom=9 (15%) and total=15 (27%)) and pot and trapping and dredging were tied for third with
each having 7 (12%) gear restrictions. Looking at just pelagic and bottom breakdown longline
and trawls amount of gear restrictions, pelagic longlines have the second least, bottom longlines
have the third most (above dredges and pot and trap), pelagic trawls have the second most and
bottom trawls have the most restrictions. In the Gulf of Mexico, trawls and longlines are the most
commonly restricted gear type (Figure 27).
COUNTS OF GEAR TYPE RESTRICTIONS: GULF OF MEXICO
30

26

COUNTS

25
20
15
15
10

9

15
11

6

5

7

7

DREDGE

POT&TRAP

5
0
LONGLINE: LONGLINE: LONGLINE TRAWL:
PELADGIC BOTTOM
TOTAL
PELADGIC

TRAWL:
BOTTOM

TRAWL
TOTAL

NET

GEAR TYPES
Figure 27. Counts of restrictions in the Gulf of Mexico by gear type.

Zonal Sea Turtle Kernel Density
Atlantic
The loggerhead is the only species of this study with relocations in the Atlantic zones.
Within the Atlantic waters 100 nautical miles off the coast of Florida there were ten regulated
zones where loggerheads KD values were found, and the zones were ≥ 450mi2 and had KD
values (Table 6).
The Florida Keys National Marine Sanctuary (FKNMS) had the highest mean kernel
density (KD) (24.6) and the second highest median (7.7) for zones in the Atlantic (Figures
28A&B). The maximum (197.3) and standard deviation (SD) (43.9) represents the high level of
variability of KD values within the zone, which suggests that there is a loggerhead hotspot within

51

the zone (Figure 28C&D). This is confirmed by the FKNMS KD map that shows a loggerhead
hotspot and its epicenter within the zone (Figures 29).

7.7 7.9

B

30.0
24.6

Mean

25.0

2.5
1.0
0.5 0.8
0.1 0.1 0.3

1.7

20.0
13.8

15.0
10.0
5.0

4.0
0.8 1.1

D

300.0

OB

LPN

FKNMS

LPS

EFC

PT

AOCA

278.9

275.7

275.7

Max

25.2
18.8
8.8
1.7 1.6

197.3

200.0

11.1

8.8

153.8

150.0
100.0

61.1

50.0

1.3

12.3 6.5

46.2

6.5

50000.0
45000.0
40000.0
35000.0
30000.0
25000.0
20000.0
15000.0
10000.0
5000.0
0.0

33319.9
24870.7
16961.8
12460.2

5275.1
547.3

OB

FKNMS

LPN

LPS

EFC

PT

AOCA

CBCA

SMT

Altantic Zones

47391.7

12524.2

AU

OB

LPN

FKNMS

LPS

EFC

PT

AOCA

CBCA

SMT

0.0

3806.1
734.1

AU
SMT
CBCA
AOCA
PT
EFC
LPS
LPN
FKNMS
OB

Area (mi2)

4.8
1.4

250.0
33.5

Altantic Zones

E

3.3

Altantic Zones

43.9

AU

Standard Deviation

50.0
45.0
40.0
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0

CBCA

AU

SMT

OB

FKNMS

LPS

LPN

EFC

PT

AOCA

CBCA

Altantic Zones

C

12.4

8.8

0.0

AU

9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0

SMT

Median

A

Figure 28. Atlantic regulated fishing zones
loggerhead kernel density: A) median B) mean C)
standard deviation D) max E) area. Atlantic
Unregulated (AU), Stetson-Miami Terrace HAPC
(SMT), Charleston Bump Closed Area (CBCA),
Allowable Octocoral Closed Area (AOCA),
Pourtales Terrace HAPC (PT), East Florida Coast
(EFC), Longline Prohibited South of 27 10'N (LPS),
Longline Prohibited North of 27 10'N (LPN), Florida
Keys National Marine Sanctuary (FKNMS) and
Oculina Bank HAPC (OB).

Altantic Zones

52

Loggerheads
Table 6. Atlantic regulated fishing zones loggerhead kernel density for median, mean, standard deviation, max and area. All raw
data except area was x1000.
Loggerhead Sea Turtles
Atlantic Zones

Median

Mean

Standard Deviation

Maximum

Area (mi2)

Stetson-Miami Terrace HAPC (SMT)
Atlantic Unregulated (AU)

0.1
0.1

0.8
4

1.7
18.8

12.3
278.9

12524.2
47391.7

Charleston Bump Closed Area (CBCA)

0.3

1.1

1.6

6.5

5275.1

Allowable Octocoral Closed Area (AOCA)

0.5

3.3

8.8

61.1

24870.7

Pourtales Terrace HAPC (PT)

0.8

1.4

1.3

6.5

547.3

1

8.8

25.2

275.7

33319.9

East Florida Coast (EFC)
Longline Prohibited South of 27 10'N (LPS)

1.7

4.8

8.8

153.8

12460.2

Longline Prohibited North of 27 10'N (LPN)

2.5

13.8

33.5

275.7

16961.8

Florida Keys National Marine Sanctuary (FKNMS)

7.7

24.6

43.9

197.3

3806.1

Oculina Bank HAPC (OB)

7.9

12.4

11.1

46.2

734.1

The Oculina Bank HAPC has the third highest mean (12.4) and the highest median (7.9)
out of all Atlantic zones (Figures 28A&B). The SD (11.1) for this zone shows that the variability
of KD points in this region was significantly lower than the previous zone, FKNMS (Figure
28C). The max (=46.2) is noticeably lower than the FKNMS maximum, (Figure 28D) reflecting
the fact that while a hotspot overlaps with the Oculina Bank HAPC, it is only partially
intersecting the zone (Figure 30). This zone has the second smallest area (734.1mi2) out of all
Atlantic zones which contributes to the median and mean KD results as the Oculina Bank
HAPC’s loggerhead hotspot interactions are limited.
The Longline Prohibited North of 27 10'N zone is the fourth largest zone (12460.2mi2)
and is tied for the second highest maximum (275.7) in the Atlantic zones (Figures 28D&E). The
median (2.5) and mean (13.8) are both the third highest out of the Atlantic zones (Figure
28A&B). The between the max and SD (33.5) this represents that there is significate KD
variation within the zone (Figure 28C). These results suggest a loggerhead hotspot, and its
epicenter, are interacting with the Longline Prohibited North of 27 10'N zone, and this is

53

confirmed by the loggerhead kernel density map (Figure 31). The size of this zone contributes to
the median and mean KD results as the Longline Prohibited North of 27 10'N zone has
noteworthy interactions with loggerhead hotspots.
The Longline Prohibited South of 27 10'N zone has a max of 153.8 and SD of 8.8
demonstrating there is some variation within this zone (Figures 28C&D). The large area
(12460.2 mi2) of the zone, median (1.7) and mean (4.8) suggest there is limited interactions with
the hotspots in this zone (Figures 28A, B, & E). The loggerhead kernel density map of the
Longline Prohibited South of 27 10'N zone confirms these results; there is one hotspot
interaction, in which the hotspot is only partially intersected by the zone (Figure 31).
The East Florida Coast zone is the 2nd largest zone in the Atlantic (33319.9mi2) (Figure
28E). The mean (8.8) and median (1) indicate that this zone has limited interactions with
loggerhead hotspots (Figure 28A&B). The maximum (275.7) and SD (25.2) show significant
variation in KD further indicating interactions with loggerhead hotspots (Figures 28C&D). These
results are confirmed by the loggerhead kernel density map of the East Florida Coast Zone. The
zone interacts with 2 hotspots, both are partially intersected by the zone boundaries, and one
hotspot’s epicenter is within the zone (Figure 32). The large size of the zone contributes to the
lower median and mean despite the significant hotspot interactions.
The Allowable Octocoral Closed Area zone is the third largest zone in the Atlantic waters
(area=734.1mi2) (Figure 28E). The mean (3.3) and median (0.5) indicate that this zone has
limited interactions with loggerhead hotspots (Figures 28A&B). The max (61.1) and SD (=8.8)
suggest that the zone intersects with a loggerhead hotspot with a low value epicenter (Figures
28C&D). This is confirmed by the loggerhead KD map as the zone partially intersects a
loggerhead hotspot with a low value epicenter (Figure 33).

54

The Pourtales Terrace HAPC is the smallest zone in that analyzed in the Atlantic waters
(547.3mi2) (Figure 28E). The mean (1.4) and median (0.8) indicate that this zone has limited
interactions with loggerhead hotspots (Figures 29A&B). The SD (1.3) and max (6.5) suggest that
this zone does not overlap with a hotspot, but instead have KD Values that are too low to be
visually indicated by the KD raster (Figures 28 C&D). The loggerhead KD map of Pourtales
Terrace HAPC zone shows no hotspots (Figure 34). The small size of this zone contributes to the
median and mean KD results as there are no visible loggerhead hotspot interactions.
The Charleston Bump Closed Area has limited hotspot interactions due to the mean (1.1)
and median (0.3) (Figures 29A&B). The max (6.5) and SD (1.6) do not demonstrate variation in
the KD, thus suggesting there are no hotspots that interact with this zone (Figures 28C&D). This
is also confirmed by the loggerhead KD map, as it shows visible loggerhead hotspot interactions
(Figure 35).
The Stetson-Miami Terrace HAPC zone has limited hotspot interactions due to low mean
(0.8) and median (0.1) data (Figures 28A&B). The max (12.3) and SD (1.7) do not demonstrate
any variation in KD, further indicating the limited hotspot interactions (Figures 28C&D). The
loggerhead KD map of the Stetson-Miami Terrace HAPC zone shows no visual interactions with
hotspots, confirming the results found (Figure 36).
The Atlantic Unregulated zone is the largest zone in the Atlantic waters (47391.7mi2)
(Figure 28E). This zone indicates limited hotspot interactions due to the mean (4) and median
(0.1) (Figures 28A&B). The max (278.9) and SD (18.8) demonstrate significant KD variation
within the zone, suggesting there is notable loggerhead hotspot interactions (Figures 28C&D).
The loggerhead KD map of the Atlantic Unregulated zone shows that that the zone interacts with
three hotspots, one completely within the zone and 2 partially intersecting (Figure 37). One of

55

the intersecting zones epicenters is within the zone boundaries. The large size of the zone
contributes to the lower median and mean despite the significant hotspot interactions.

Figure 29. Florida Keys National Marine Sanctuary loggerhead KD hotspot map.

Figure 30. Oculina Bank HAPC loggerhead KD hotspot map.

Figure 31. Longline Prohibited: North of 27 10'N (purple) and
South of 27 10' loggerhead KD hotspot map.

56

Figure 32. East Florida Coast loggerhead KD hotspot map.

Figure 33. Allowable Octocoral Closed Area loggerhead KD hotspot map.

57

Figure 34. Pourtales Terrace HAPC loggerhead KD hotspot map.

Figure 35. Charleston Bump Closed Area loggerhead KD hotspot map.

58

Figure 36. Stetson-Miami Terrace HAPC loggerhead KD
hotspot map.

Figure 37. Atlantic Unregulated loggerhead KD hotspot map.

Gulf of Mexico
Both loggerhead and leatherback turtles were relocated within 100 nautical miles of the
coast of Florida in the Gulf of Mexico. Turtle KD values were found in a total of 9 regulated
fishing zones found in the Gulf of Mexico, which the zones were ≥ 450mi2 and had KD values.
Using these perimeters loggerheads were found in 6 zones and leatherbacks were found in 7
zones (Table 7&8).
The Tortugas Shrimp Sanctuary North zone is the smallest zone where loggerheads KD
values were found in the Gulf of Mexico (1352.1mi2) and has the highest mean (29.1) and
median (20.5) (Figures 38A&B). The maximum (91.4) and SD (8.8) show variation within the
Tortugas Shrimp Sanctuary North zone, indicating loggerhead hotspot interactions (Figures
38C&D). The loggerhead KD map of this zone shows this zone is interacting with 2 loggerhead

59

hotspots, both are partially intersected within the zone (Figure 39). One hotspot is primarily in
the Tortugas Shrimp Sanctuary North zone and with its epicenter inside the zone, which

GoMU

TSS-N

SWFTC

RFSA-WC

BLP

RFLR

GoMU

0

Gulf of Mexico Zones

Gulf of Mexico Zones

35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0

D
Max

150.0
50.0

TSS-N

SWFTC

RFSA-WC

BLP

GoMU

TSS-N

SWFTC

BLP

RFLR

RFSA-WC

0.0

Gulf of Mexico Zones
Figure 38. Gulf of Mexico regulated fishing zones
loggerhead kernel density: A) median B) mean C)
standard deviation D) max E) area. Gulf of Mexico
Unregulated (GoMU), Reef Fish Longline
Restriction (RFLR), Bottom Longline Prohibited
(BLP), Reef Fish Stressed Areas, FL West Coast
(RFSA-WC), Southwest Florida Trawl Closure
(SWFTC) and Tortugas Shrimp Sanctuary North
(TSS-N).

60000.0
50000.0
40000.0
30000.0
20000.0
10000.0

TSS-N

SWFTC

RFSA-WC

BLP

RFLR

0.0

GoMU

Area mi2

250.0

100.0

Gulf of Mexico Zones

E

300.0
200.0

GoMU

Standard Deviation

C

TSS-N

5

SWFTC

10

RFSA-WC

15

Mean

Median

20

35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0

BLP

B

RFLR

25

RFLR

A

Gulf of Mexico Zones

60

confirms the maximum. The other hotspot is only partially within the zone, with the lowest value
edge (29 to 56 KD) of the hotspot intersecting within the zone for .8 miles. The small size of
the zone and majority enveloped hotspot would contribute to the high mean, median and the
lower SD KD values.

Loggerheads
Table 7. Gulf of Mexico regulated fishing zones loggerhead kernel density for median, mean, standard deviation, maximum and
area. All raw data, except area, is x1000.

Loggerhead Sea Turtle Kernel Density
Median

Mean

Standard
Deviation

Maximum

Area (mi2)

Gulf of Mexico Unregulated (GoMU)

0

3.2

19.5

253.9

52390.5

Reef Fish Longline Restricted (RFLR)

0

8.3

29.3

254

30605.4

0.3

7.8

28.1

254

34322.5

1

12.4

30.6

254

11703.9

Southwest Florida Trawl Closure (SWFTC)

4.4

21.4

27.2

91.4

1925.4

Tortugas Shrimp Sanctuary North (TSS-N)

20.5

29.1

28.8

91.4

1352.1

Gulf of Mexico Zones

Bottom Longline Prohibited (BLP)
Reef Fish Stressed Areas, FL West Coast (RFSA-WC)

The Southwest Florida Trawl Closure zone is the second smallest zone (1925.4 mi2) that
loggerheads KD values were found in the Gulf of Mexico (Figure 38E). The mean (21.4) and
median (4.4) indicate loggerhead hotspot interaction, which is further corroborated by the
significant variation in KD seen by the maximum (91.4) and SD (27.2) (Figures 38A, B, C&D).
The loggerhead KD map of the Southwest Florida Trawl Closure zone display interactions with 3
different hotspots (Figure 40). Two hotspots have very mild interactions with the zone, only
intersecting a max of 7.5 miles into the into the zone with the lowest value edge (29 to 56 KD)
of the hotspot. The third hotspot has most of its area enveloped within the zone, which confirms
the maximum. The small size of the zone and majority enveloped hotspot would contribute to the
high mean and median KD values found within this zone.

61

The Bottom Longline Prohibited zone is the second largest zone that loggerheads are
found the Gulf of Mexico (34322.5mi2) (Figure 38E). The mean (7.8), median (0), maximum
(254) and SD (28.1) show significant variation in limited KD, this indicates that there is hotspot
interaction, with high value hotspots, but it is limited (Figures 38A, B, C&D). This is confirmed
by the Loggerhead KD map of the Bottom Longline Prohibited zone as it shows 7 hotspot
interactions: 4 epicenters (2 of which are completely within and 2 partially intersecting the zone)
and 3 partial hotspot interactions (Figure 41). The 4 hotspot epicenters within the zone had KD
values ranging between 29 to 254 (maximum). The 3 hotspots partially intersecting with the
Bottom Longline Prohibited zone have KD values ranging between 29 to 195. The large size of
the zone contributes to the lower mean and median KD despite the high maximum and SD due to
the hotspot interactions.
The Reef Fish Stressed Areas, Florida West Coast zone’s mean (12.4), median (1),
maximum (254) and SD (30.6) represent significant KD variation within the zone, indicating
loggerhead hotspot interactions (Figures 38A, B, C&D). The loggerhead KD map of the Reef
Fish Stressed Areas, FL West Coast zone shows that seven different hotspots interact partially
with the zone (Figure 42). Three hotspots have over half the hotspot area within zone, including
their epicenters which range in KD value between 29 to 254 KD (maximum). The remaining four
hotspots interacting with the Reef Fish Stressed Areas, FL West Coast zone do not have
epicenters within the zone and intersect the zone up to  6.25miles, and the KD values range
between 29 to 167. The larger size of this zone (11703.9 mi2) contributes to the lower mean and
median KD despite the higher maximum and SD KD (Figure 38E).
The Reef fish Longline Restricted zone is second largest zone (30605.4mi2) in the Gulf of
Mexico in which loggerhead KD values area found (Figure 38E). The mean (8.3), median (0),

62

maximum (254) and SD (29.3) demonstrate KD variation, which indicates the zone has
interactions with loggerhead hotspots (Figures 38A, B, C&D). The loggerhead KD map of Reef
fish Longline Restricted zone so this zone is interacting with 7 hotspots (Figure 43). Four of the
7 hotspots are fully, or majority enveloped in the zone and have epicenter KD values ranging
between 29 to 254 (maximum). The remain 3 zones partially intersect up to 3miles, with KD
values between 29 to 167. The large size of this zone contributes to the lower mean and median
KD despite the higher maximum and SD KD.
The Unregulated Gulf of Mexico zone is the largest zone (52390.5mi2) in the Gulf of
Mexico in which loggerhead KD values area found (Figure 38E). The mean (3.2), median (0),
maximum (253.9) and SD (19.5) exhibit variation in the KD, indicating there is loggerhead
hotspot interactions within this zone (Figures 38A, B, C&D). The loggerhead KD map of the
Unregulated Gulf of Mexico zone shows 6 hotspot interactions, all partially interesting with the
zone (Figure 44). 2 hotspots have their epicenters within the zone, with KD values ranging
between 29 to 223. The remaining 4 hotspots intersect up to 7miles into the zone and have KD
values ranging between 29 to 253.9 (maximum). The hotspots that do not have the epicenter
within the zone have higher KD values than the hotspots with their epicenter within the zone.
The large size of this zone contributes to the lower mean and median KD despite the higher
maximum and SD KD.

63

Figure 40. Tortugas Shrimp Sanctuary North loggerhead KD
hotspot map.

Figure 39. Southwest Florida Trawl Closure loggerhead KD
hotspot map.

Figure 42.Bottom Longline Prohibited loggerhead KD hotspot Figure 41. Reef Fish Stressed Area, FL West Coast loggerhead
map.
KD hotspot map.

64

Figure 43. Reef Fish Longline Restricted loggerhead KD
hotspot map.

Figure 44. Gulf of Mexico Unregulated loggerhead KD hotspot
map.

Leatherbacks
There was a limited leatherback relocation data available for this study. Due to this
limitation the KD values of the leatherbacks are much lower than what was seen in the
loggerhead data.
Table 8. Gulf of Mexico regulated fishing zones leatherback kernel density for median, mean, standard deviation, max and area.
All raw data except area was x1000.

Leatherback Sea Turtles Kernel Density
Median

Mean

Standard
Deviation

0

0.2

0.4

2.4

11703.9

0

0.7

1.3

16.2

34322.5

Gulf of Mexico Unregulated (GoMU)

0.1

2

3.6

22.4

52390.5

Middle Grounds HAPC (MG)

1.3

1.5

1

3.3

450.0

Reef Fish Longline Restricted (RFLR)
Reef Fish Stressed Areas, FL, AL and MS (RFSAMS)
The Edges (Edges)

1.5

1.5

2.6

16.3

30605.4

2.8

3.5

2.7

11.3

3810.5

10

10

1.6

14.2

516.5

Gulf of Mexico Zones
Reef Fish Stressed Areas, FL West Coast (RFSAWC)
Bottom Longline Prohibited (BLP)

Max

Area
(mi2)

65

10
8
6
2.8

4
0

1.5

1.3

0.1

0

12.0
8.0
6.0

3.5

4.0
2.0

0.2 0.7

D
1.6

1.3

Area (mi2)

Edges

RFSA-MS

RRFLR

22.4

25.0
20.0

2.7

1

0.4

Max

2.6

16.3

16.2

15.0

14.2
11.3

10.0
5.0

3.3

2.4

60000.0

52390.5
34322.5

30605.4

30000.0
20000.0 11703.9
10000.0

3810.5
516.5

450.0

Edges

RFSA-MS

RRFLR

MG

Figure 45. Gulf of Mexico regulated fishing zones
leatherback kernel density: A) median B) mean C)
standard deviation D) max E) area. Gulf of Mexico
Unregulated (GoMU), Reef Fish Longline Restriction
(RFLR), Bottom Longline Prohibited (BLP), Reef
Fish Stressed Areas, FL West Coast (RFSA-WC),
Reef Fish Stressed Areas, FL, AL and MS (RFSAMS), Middle Grounds HAPC (MG) and The Edges
(Edges)

Edges

RFSA-MS

RRFLR

MG

GoMU

BLP

0.0

RFSA-WC

GoMU

Gulf of Mexcio Zone

50000.0
40000.0

RFSA-WC

Edges

RFSA-MS

RRFLR

MG

BLP

GoMU

0.0

Gulf of Mexcio Zone

E

1.5 1.5

Gulf of Mexcio Zone

3.6

RFSA-WC

Standard Deviaiton

4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0

BLP

RFSA-WC

Edges

RFSA-MS

RRFLR

MG

GoMU

BLP

Gulf of Mexcio Zone

C

2

0.0

RFSA-WC

0

10

10.0

BLP

2

B

MG

10

GoMU

12

Mean

Median

A

Gulf of Mexcio Zone

The Edges zone is the second smallest zone (516.5mi2) in the Gulf of Mexico in which
leatherback KD values area found (Figure 45E). The mean (10.0), median (10.0), max (14.2) and
SD (1.6) exhibit variation in KD, indicating that this zone interacts with a leatherback hotspot
(Figures 45A, B, C&D). The Leatherback KD map of the Edges zone confirms this as the whole

66

zone is within a region of a single large hotspot (Figure 46). The Edges Zone is within a region
of this hotspot that has KD values ranging between 5 to 16.
The Reef Fish Longline Restricted zone is the third largest zone (30605.4mi2) in the Gulf
of Mexico in which leatherback KD values are found (Figure 45E). The mean (1.5), median (1.5)
(figures maximum (16.3) and SD (2.6) exhibit variation in KD, indicating that this zone interacts
with a leatherback hotspot (Figures 45A, B, C&D). The Leatherback KD map of the Reef Fish
Longline Restricted zone confirms this as the zone that intersects with one large hotspot along its
northern end (Figure 47). The region this Reef Fish Longline Restricted zone intersects with is
the hotspot that is not on an epicenter but instead the outer edges of the zone; the KD values it
intersects range between 3 to 16.3 (maximum). The large size of the zone contributes to the
lower KD mean and median values, despite the significant max and SD values.
The Middle Grounds HAPC zone is the smallest zone (450.0mi2) in the Gulf of Mexico
were leatherback KD values area found (Figure 45E). The mean (1.5), median (1.3), maximum
(3.3) and SD (1) exhibit little variability in KD, indicating limited leatherback hotspot
interactions (Figures 45A, B, C&D). The Leatherback KD map of the Middle Grounds HAPC
zone confirms this, as the zone only interacts with a low KD value (3 to 4 KD) edge of a hotspot,
intersecting up to 6.8miles into the zone (Figure 48). The small size of the zone contributes to
the higher overall median and mean KD values.
The Unregulated Gulf of Mexico zone is the largest zone (52390.5mi2) in the Gulf of
Mexico where leatherback KD values area found (Figure 45E). The mean (1.9), median (0.1),
maximum (22.4) and SD (3.6) show there is significant variation in KD throughout this zone,
indicating there are prevalent interactions with leatherback hotspots (Figures 45A, B, C&D). The
leatherback KD map of the Unregulated Gulf of Mexico zone confirms this, as the majority of

67

the hotspot intersects with the zone, including the epicenter (Figure 49). The KD Values of the
hotspot that interest with the zone range between 3 to 22.4 (maximum). The large size of the
zone contributes to the lower median and mean KD values, despite having the highest SD and
max out of all the other zones in the Gulf of Mexico.
The Bottom Longline Prohibited zone is the second largest zone (34322.5mi2) in the Gulf
of Mexico where leatherback KD values are found (Figure 45E). The mean (0.7), median (0),
maximum (16.2) and SD (1.3) shows that the Bottom Longline Prohibited zone has limited
variation in KD, indicating limited hotspot interactions (Figures 45A, B, C&D). This is
confirmed by the leatherback KD map of the Bottom Longline Prohibited zone, as only the north
easter edge of the zone interacts partially with 2 hotspots (Figure 50). These hotspots intersect up
to 68miles within the zone. One hotspot’s epicenter is within the zone, with KD values ranging
between 8 to 9. The KD value range for the hotspot without the epicenter inside the zone is 3 to
16.2 (maximum). The large size of this zone contributes to the lower median and mean KD
despite the higher max.
The Reef Fish Stressed Areas, FL West Coast zone is indicated to have extremely limited
leatherback hotspot interactions by the minimal KD variation seen by the mean (0.2), median (0),
maximum (2.4) and SD (0.4) (Figures 45A, B, C&D). The leatherback KD map of the Reef Fish
Stressed Areas, FL West Coast zone confirms this, as the was only one very minor hotspot
interaction, with a KD value between 3 to 4, seen in the north easter corner of the zone (Figure
51).
The Reef Fish Stressed Areas, Florida, Alabama and Mississippi zone is shown to have a
significant amount of leatherback hotspot interactions due to higher max (11.3), mean (3.5) and
median (2.8) but limited variation shown by the SD (2.7) (Figures 45A, B, C&D). The

68

leatherback KD map of the Reef Fish Stressed Areas, FL, AL and MS exhibits one hotspot
interaction with a large hotspot throughout the majority of the zone (Figure 51). The hotspot
region that is intersecting partially with the zone does not contain the epicenter and has a KD
value range between 3 to 11.3 (maximum).

Figure 46.
The Edges
leatherback
KD hotspot
map.

Figure 47.
Reef Fish
Longline
Restricted
leatherback
KD hotspot
map.

69

Figure 48.
Middle grounds
leatherback KD
hotspot map.

Figure 49.
Gulf of
Mexico
Unregulated
leatherback
KD hotspot
map.

70

Figure 50.
Bottom
Longline
Prohibited
leatherback
KD hotspot
map.

Figure 51.
Reef Fish
Stressed
Areas: Fl
West Coast
and Fl, Al
and MS
leatherback
KD hotspot
map.

71

Gear and Kernel Density Relationships
Regulated Fishing Zone Kernel Density and Gear Restrictions
The median KD of turtle relocations in regulated fishing zones was not significantly
related to the number of fishing gear restrictions in those zones, for both loggerheads and
leatherbacks in the Atlantic and Gulf of Mexico (Figures 30, 31 & 32) Values of median KD
were quite variable and so each plot had substantial scatter. For loggerheads in the Atlantic, the
two zones with the highest medians (Florida Keys National Marine Sanctuary (FKNMS) and
Oculina Bank HAPC zones)

Atlatnic Median Kernel Density VS Gear
Restriction Counts: Loggerhead
9.0

zones with very different gear
restriction counts (Figure 30).
For loggerheads in the Gulf of

Median Kernel Density

were also the two smaller fishing

6.0
4.5
LPN

3.0

LPS

1.5

EFC
CBCA

AOCA

Mexico, variation in gear

U-A

0.0
0

1

maximum in gear restriction

KD, in part due to its large size

6

7

8

TSSN

20.0

15.0
10.0
5.0
0.0

SWTC
RFSA-WC

UGoM
0

count (7) and had a low median

5

Gulf of Mexico Median Kernel Density VS Gear
Restriction Counts: Loggerhead

25.0

Median Kernel Density

results since it was at the

4

Figure 52. Atlantic Ocean loggerhead regulated fishing zones gear counts and
median kernel density do not have a significant relationship (F1,8 = 1.28, p =
0.29, R2 = 0.14).

Mexico, the Reef Fish Longline

leverage on the nonsignificant

SMT
3

Gear Restictions Count

leatherbacks in the Gulf of

Restriction zone had high

PT
2

restriction counts were very
limited (0-2, Figure 31). For

FKNMS

OB

7.5

RFLR

BLP
0.5

1

1.5

2

2.5

Gear Restiction Counts

Figure 53. Gulf of Mexico loggerhead regulated fishing zones gear counts and
median kernel density do not have a significant relationship (F1,4 = 1.28, p =
0.32, R2 = 0.24).

(30605.4mi2).

72

Gulf of Mexico Zones' Median Kernel Density VS Gear
Restriction Counts: Leatherback

12

Median Kernel Density

10

Edges

8
6
4
RFSA-MS
2

UGoM

RFSA-WC

0
0

RFLR

MG

BLP
1

2

3

4

5

Gear Restiction Counts

6

7

8

Figure 54. Gulf of Mexico leatherback regulated fishing zones gear counts and
median kernel density do not have a significant relationship (F1,5 = 3.57, p =
0.12, R2 = 0.42).

Relationship Between Zone Density and Restricted Gear Type
Across all the regulated fishing zones and both species there was constantly more
restricted gear types (longline [pelagic, bottom, and total], trawl [pelagic, bottom, and total], net,
dredge and pot and trap) for higher median KD (≥1) zones than low median KD (>1) zones
(Figure 55A, B&C). This indicates that higher median KD of turtle relocations in regulated
fishing zones were associated with higher restrictions of each gear type.
Atlantic
Loggerhead
In the Atlantic, zones with a loggerhead relocation median KD of ≥1 (the top 50%, Table
7) had more gear restrictions in two out of the seven gear types (42%) than the zones with
median KD <1 (Figure 55A). The two gear types are longline, which accounted for 30% (pelagic
and bottom=15%), and net, which accounted for 4% of all restrictions. This shows that in the
Atlantic, higher restrictions of longlines and nets are associated with higher median KD of
loggerhead relocations. However, across all gear types, there was not a significant difference in
gear restrictions in zones with higher median KD than zones with lower KD (paired t8 = -1.5, p =
0.172).

73

Gulf of Mexico
Loggerhead
In the Gulf of Mexico, zones with a

A

loggerhead relocation median KD of ≥1 (the

5 out of 7 gear types (71%) than the zones with
<1 (Figure 55B). These gear types are trawls,

Low

8

which accounted for 33% (pelagic and

6

4

2

0
Longline: Longline: Longline: Trawl: Trawl: Trawl:
Pelagic Bottom Total Pelagic Bottom Total

Net

Dredge

Gear type

bottom=17%) of all gear restrictions, and nets,
dredges and pot and traps, which each

High

10

Restricted Gear Counts

top 50%, Table 8), had more gear restrictions in

12

B

Pot &
Trap

6

Low

High

Dredge

Pot &
Trap

accounted for 8% of restrictions. This shows
that in the Gulf of Mexico higher restrictions of
trawls, nets, dredges and pot and traps are

Restricted Gear Counts

5

associated with higher median KD of

4

3

2

1

0

loggerhead relocations. However, across all

Longline: Longline: Longline: Trawl: Trawl: Trawl:
Pelagic Bottom Total Pelagic Bottom Total

Net

Gear type

gear types, there was not a significant

C

Leatherbacks
In the Gulf of Mexico, zones with a

Restricted Gear Counts

(paired t8 = -1.87, p = 0.09435).

Low

5

4

3

2

1

0
Longline: Longline: Longline: Trawl: Trawl: Trawl:
Pelagic Bottom Total Pelagic Bottom Total

leatherback relocation median KD of ≥1 (the
top 57%, Table 9), had higher numbers of gear
restrictions across all gear types than the zones

High

6

difference in gear restrictions in zones with
higher median KD than zones with lower KD

7

Net

Dredge

Pot &
Trap

Gear type

Figure 55. Zone median kernel density and its relationship
with gear type restrictions. A) Atlantic zones with
Loggerhead Median KD B) Gulf of Mexico zones with
loggerhead median KD C) Gulf of Mexico zones with
loggerhead median KD.

74

with median KD <1 (the bottom 50%, Figure 55C). Across all gear types, in the Gulf of Mexico,
there tended to be more gear restrictions in zones with higher median KD than zones with lower
KD (paired t8 = -6.825, p < 0.001).

75

Discussion
Hotspots Usage
Based on the relocations of individuals within 100 nm of Florida’s coastline there are
nine loggerhead hotspots (Figure 56) and three leatherback hotspots (Figure 57). Three of the
loggerhead hotspots are in the Atlantic, with the remaining 6 and all 3 leatherback hotspots in the
Gulf of Mexico (Figures 56 & 57). These hotspots were created from relocations between all the
years of the study; thus, the hotspots do not reflect accurate yearly regional uses, but instead
identify regions of common use by turtles along the Florida coast between 2005 to 2017.

Loggerheads
Nine loggerhead relocation hotspots were found within the study area and fell into 4
usage areas around Florida: 1) eastern central Florida coast, 2) Florida Keys 3) western central
Florida coast and 4) the Florida panhandle. Eastern central Florida coast was the most commonly
used area, second to western central Florida coast, then Florida Keys and lastly Florida
panhandle region. High use areas are areas were KD values between 113 to 279. There is a
strong possibility that these regions are used for various different needs during nesting season
such as foraging, nesting, and breeding.
There is only one hotspot found in the along the eastern central Florida coast, hotspot 1
(Figure 56). It is the largest loggerhead relocation hotspot found in both the Atlantic and Gulf of
Mexico, measuring 165 miles in length. Hotspot 1 along the continental shelf and has a depth of
<200m, which are both foraging preferances of loggerheads (GEBCO, 2021; Griffin et al., 2013,
United States & National Marine Fisheries Service, 2013). This hotspot is located in the South
Atlantic Blight SAB, which is a known foraging ground, both seasonal (summers) and yearround (Figures 5&6; Ceriani et al., 2012; Ceriani et al., 2017). High use areas are roughly

76

between Brevard, Indian River and St. Lucie counties, which hold 47% (46,333) of nesting in the
eastern Florida and 40% of all nesting statewide (FFWCC, 2023).The epicenter alone is
15miles in length, north to south, and maximum KD is 278.9, indicating the eastern central
Florida coast to be the highest used area by loggerheads, most commonly used as a nesting and
foraging ground (Figure 56).
There are 3 loggerhead relocation hotspots (hotspots 2, 3 and 4) in the second usage area,
the Florida Keys (Figure 56). Both hotspot 3 (east of Key West, Fl) and 4 (northeast of Key
West, Fl) area located along the USA continental shelf at depts of <200m (GEBCO, 2021). Fifty
percent of foraging from a loggerhead Northwest Atlantic District Population Subgroup (NWA
DPS) subgroup, the Peninsular Florida Recovery Unit (PFPU), is in the Subtropical Northwest
Atlantic (SNWA), in which the Florida Keys are located (Pfaller et al., 2020). Nesting in Monroe

Figure 56. Loggerhead Relocation kernel density hotspots. 9 hotspots between 4 usage areas:
eastern central Florida coast (hotspot 1) Florida Keys (hotspots 2, 3 and 4) western central
Florida coast (hotspots 5, 6 and 7) and Florida panhandle (hotspots 8 and 9).

77

County (where the Florida Keys are) is only 0.5% (457) of nesting in the eastern Florida and
0.4% statewide; however, this area is a known breeding habitat for the PFPU (NMFS Office Of
Protected Resources, 2023; FFWCC, 2023). Hotspot 2 is the only area where a hotspot is located
off the USA continental shelf instead it is across the Florida strait on the north edge of the Cay
Sal Bank in the Bahamas but is still within the SNWA (Figure 56; Figure 5). The Cay Sal Bank
has depths between 7 to 30m, with coral reefs, sea grasses and macroalgae that could sustain
benthic biota, all known loggerhead foraging preferances (Purkis et al., 2014; Griffin et al.,
2013). Despite this both hotspots 2 and 4 are lower use hotspots with KD values ranging between
29 to 84. The only hotspot within the Florida Keys area that is a high usage area is hotspot 3,
measuring 40 miles in length and has a KD maximum of 197.3 (Figure 56). This suggests that
these hotspots are used for most commonly as breeding and foraging grounds with limited
nesting.
The western central Florida coast usage area has 3 loggerhead relocation hotspots,
hotspots 5, 6 and 7 (Figure 56). Each of these hotspots are along the USA continental shelf at
depts of <200m (GEBCO, 2021). The Gulf of Mexico is a very productive environment and is
home to many of the food sources loggerheads prefer such as crustations and fish (Alongi, 2020;
Smith, 1982; Richardson & McGillivary, 1991) A 2017 study, by Ceriani et al., identified west
coast of Florida as a foraging hotspot for loggerheads, with 16% of the easter PFRU and 47% of
western PFRU forage in the region (Pfaller et al., 2020; Ceriani et al., 2017; Figure 6). Counties
in western central Florida coast area are Collier, Lee, Charlotte and Sarasota, which together
account for 81% (14,517) of western Florida nesting and 15% of nesting statewide (FFWCC,
2023). This suggests that the western central Florida coast is used primarily as a nesting and
foraging grounds. All 3 hotspots in this have high use areas, hotspot 5 is 22 miles in length,

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with KD value maximum of 122.5, hotspot 6 is 32 miles in length, with KD value maximum of
242.3 and hotspot 7 is 37 miles in length, with KD value maximum of 253.9. The western
central Florida coast is the second most used region within the area of study.
The Florida panhandle usage area has only 2 loggerhead relocation hotspots, hotspot 8
and 9 (Figure 56). Each of these hotspots are along the USA continental shelf at depts of <200m
(GEBCO, 2021). As the Florida panhandle usage area is also in the Gulf of Mexico, this area is
also home to many of loggerheads preferred food sources (Alongi, 2020; Smith, 1982;
Richardson & McGillivary, 1991). A 2020 study, by Pfaller et al., found that 14% of the western
PFRU and 14% of the western PFRU forage in the NGoM, where the Florida panhandle usage
area is located. There is limited data on nesting in the counties along the panhandle, only
counties east of the high usage hotspots had nesting data. These counties are Pinellas, Franklin,
Gulf, Bay, Walton, Okaloosa, Santa Rosa and Escambia, which all together accounted for 11%
of nesting along the west Florida coast but only 2% of statewide nesting (FFWCC, 2023). This
suggests that the Florida panhandle usage area is used primarily for foraging and has some
limited nesting as well. Hotspot 8 is the only hotspot in this usage area that has high use, and it is
33 miles in length, with KD value maximum of 197.1 (Figure 56).

Leatherbacks
There are 3 leatherback relocation kernel density hotspots found within the study area
and fell into only one usage area, the Florida panhandle (Figure 57). There is also a strong
possibility that these regions are used for various different needs during nesting season such as
foraging, nesting, and breeding, as is suggested for the loggerheads. High use areas are areas
were KD values between 12 to 22. The difference between maximum KD values for loggerheads

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and leatherbacks reflects the number of relocations of each species (n = 34 for loggerheads, n =
11 for leatherbacks) used in this analysis.
The Hotspots along the USA continental shelf are found between two depth ranges.
Hotspots 2, 3 and the northeastern half of 1 were at depts of <200m, however the southwestern
half of 1 has a depth range between 200m to 2,000m, both of which are depth ranges that
leatherbacks to forage within (GEBCO, 2021; NOAA, 2022b). Leatherback nesting data along
the Florida panhandle is nearly nonexistent with only one nest found in that region in 2022
(FFWCC, 2023). This shows that the Florida panhandle is likely used as a foraging ground, as
inter-nesting females forgare within 100 km of nesting regions and leatherbacks are migratory
foragers (NMFS, NOAA, & USFWS, 2020; FFWCC, 2023; National Marine Fisheries Service &
U.S. Fish and Wildlife Service, 2020). This is further conferemd as a 2021 study by Sasso et al.,
found that the Florida panhandle region was a high use foraging ground used by post nesting
females (Figure 14) as well as a 2014 study found there was high seasonal use between August

Figure 57. Leatherback relocation kernel density hotspots. 3 hotspots in the Florida panhandle
(hotspots 1, 2 and 3). High use areas are: Central Panhandle (CP) and South Panhandle (SP).

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to September (Fossette et al., 2014; NOAA, & USFWS, 2020). Within the Florida panhandle
usage area only hotspot 1 is consisted high use, and it is 293 miles in length. This hotspot is
unique as it has 2 high use areas within it, due to its large size. The first high use area Central
Panhandle (CP) and is 137miles in length with a KD value maximum of 22.3. The second high
use area is South Panhandle (SP) and is 21 miles in length and with a maximum KD value of
9.6, with KD value maximum of 14.4. The CP high use area is very long, however its width
ranges between is 6 to 32miles.

Migratory Corridors
Both loggerheads and leatherbacks in this study show evidence of migratory corridors
(Figures 20, 21, 56 and 57). The relocation maps (figures 20 and 21) show similarities between
the relocation movements of the turtles in this study and those in other studies. Further research
is needed to identify the movements of the loggerheads and leatherbacks in this study; however,
some indicators are present on the relocation and hotspot maps.
Figures 10 and 11 highlight migration five corridors used by loggerheads during and after
nesting season off the Florida Coast, 1) central east Florida moving to norther Atlantic Coast, 2)
southwestern Florida to Bahamas/Cuba, 3) eastern Florida Panhandle southwest to Yucatán
Peninsula, Mexico, 4) eastern Florida panhandle southeast down coast, 5) southeastern Florida
coast to central Atlantic Ocean (Foley et al., 2013; Ceriani et al., 2012). Three out of five of
these previous identified migratory corridors (corridors 1, 2 and 5), are seen reflected on the
loggerhead relocation map (Figure 20). The hotspots also align with corridors 2 (hotspot 2) and 4
(hotspot 1, 3 and 4) providing stronger evidence as they highlight possible foraging activity
along these pathways which is commonly seen during loggerhead migrations (Ceriani et al.,
2017; Ceriani et al., 2012; Foley et al., 2013).

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Leatherback migrations tend to be on a significantly larger scale then loggerheads, due to
this the identification of possible leatherback migratory corridors is more speculative as I only
had relocation data for a limited area (up to 100nm off Florida coast). Figures 12, 13 and 14
recognized two migratory corridor, 1) Yucatan Channel to western Florida continental shelf in
summer, 2) western Florida to north Atlantic through the Florida Strait from summer to fall
(Evans et al., 2021; Sasso et al., 2021). the relocation maps show heavy movements of
leatherbacks along the western Florida continental shelf, particularly near the panhandle, as well
as two individuals with movements southward (Figure 21 and 57). Due to the limited study area
and lack of study on movement timestamps, I am unable to determine if the two southwardmoving leatherbacks are migrating towards either the Yucatan Channel or Florida Strait. The
presences of leatherbacks along the western Florida continental shelf in the summer aligns with
two possible migration corridors but further research is needed in order to identify which
corridor, if either, being utilized by the leatherbacks in this study.

Risk Assessment
Commercial fishing gear harms sea turtles whether via interaction, injury or mortality,
with longlines and trawls, historically, being the worst offenders (Finkbeiner et al., 2011). The
result of this study partially supports my hypotheses, regulated fishing zones with higher turtle
relocation median KD does not have higher gear restrictions however regulated fishing zones
with higher turtle relocation median KD do have higher longlines and trawl restrictions. This
shows that commercial fishing gear restrictions on longlines and trawls, allow for more turtles to
thrive in areas in which the restrictions are in place.
Given these results, all the loggerhead and leatherback relocation KD hotspots must be
reviewed to see where longline and trawl restrictions may be lacking. In order to determine this, I

82

reviewed each of the hotspots (Figures 56 &57) and determine if the high use areas of each of the
hotspots have gear restrictions.
7 out of the 9 loggerhead hotspots had longline and trawl restrictions over high use areas
(Figure 58). Hotpot 1 has longline (pelagic & bottom) restrictions over a majority of its area but
is lacking trawl restrictions in federal waters. The  1/4 of hotspot 1 not in federal waters had
longline, trawl, and net restrictions placed on by the state; all Florida state waters hold these
restrictions. Hotspot 2 was the other hotspot unprotected by regulations, this is due to the hotspot
being outside out the USA EEZ and instead within the Bahamas EEZ, thus is outside of the
USA’s jurisdiction. Lastly hotspots 6 though 9 have sufficient longline (pelagic and bottom) and
bottom trawl restrictions acroases the majority of the hotspots’ areas but are lacking pelagic trawl
restrictions. All the loggerhead relocation KD hotspots have at minimum restrictions on either
longline or trawls even if it is only in part of the water column.
The three leatherback relocation KD hotspots are lacking gear restrictions on one or both
trawls and longlines. Hotspot 1 has  1/3 of its area protected with longline (pelagic & bottom),
and bottom trawl restrictions, however 2/3 of hotspot 1 have no restrictions. As this is the
largest hotspot between both sea turtle species this is, poses a threat to leatherbacks. Hotspot 2
only have bottom longline restrictions and is lacking pelagic longline and trawl (pelagic and
bottom) restrictions. Lastly, hotspot 3 has restrictions for longlines (pelagic and bottom) over the
majority of its area but lacks any trawl restrictions. Overall, the leatherback relocation KD
hotspots all face significant threats due to the lack of regulations in regions they are most
prominent.

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Recommendations
Federal and state regulations on commercial fishing such as the regulated zones, gear
speciation’s, bycatch mitigation gear/particles, and gear check/soak times have all contributed to
reduce sea turtle bycatch significantly (USFWS &DOI, 2013; FAC & FAR, 2023; Finkbeiner et
al., 2011). As the risk assessment in the previous section showed, most of the turtle relocation
KD hotspots have limited gear restrictions in place and need further restrictions to allow for
sufficient turtle protections. Given the risks that the sea turtles still face by commercial fishing
gear in the Florida, further steps should be taken to provide these threatened and endangered
species more protections. Limiting commercial fishing high use areas or add gear restrictions for
longlines and trawls in high usage areas, are realistic next steps to protect the sea turtles. These
recommendations are only for use during the nesting seasons on loggerheads (June to
September) and leatherbacks (May to September) (FFWCC, 2023).
Commercial fishing is a prominent part of Florida’s economic system and provides
livelihood to many Florida citizens. Thus, fishing closures areas could put additional strain on
these citizens. For example, in 1994, Amendment Three of the Florida Constitution was enacted
which banned the use of entangling nets (e.g., gill and trammel nets) in Florida state waters. This
caused a drop of 15% in saltwater product licenses, a requirement for commercial fisheries,
showing a substantial drop in the industry as 25% of net fishers retired from commercial fishing
(Adams et al., 2003). This provides context to the impacts of gear restrictions and fishing courses
on the people in Florida.
Closing the areas with sea turtle relocation KD hotspots would be ideal to reduce
interactions, injuries and mortality, however this is unrealistic as many of these hotspots are quite
large and would result in large swaths of waters in which fisheries would have to avoid, resulting
undo strain on the livelihoods of those in the fishing industry. To reduce size of closures, I have

84

identified high use areas of loggerheads and leatherbacks within each hotspot (Figure 58).
Placing closures between June to September for loggerhead hotspots, Big Bend (BB), Port
Charlotte (PC), Cape Coral (CC), Bonita Springs (BS), Key West (KW) and Palm Bay (PB), and
May to September for Leatherback hotspots, South Panhandle (SP) and Central Panhandle (CP),
should reduce this strain and significantly reduces the areas of closure (from  29,689 mi2 to
5,129 mi2), while still providing sufficient turtle protections. Currently only six regulated fishing
zones have full closures to all fishing and gear usage, Tortugas Marine Reserve, The Edges,
Madison and Swanson Marine Reserve, Steamboat Lumps Marine Reserve and the Florida Keys
National Marine Sanctuary. The combined area of all of these zones is 6,134mi2, and the largest
zone closure being Florida Keys National Marine Sanctuary,  3802mi2. This would add create a
total of 11,263mi2 (some closed zones overlap with recommended high use closures), which
could put a strain on the Commercial fishing industry.
Another option would be to place gear restrictions on trawl (pelagic and bottom) and
longlines (pelagic and bottom) over each of the high use areas for nesting seasons, on
loggerheads (June to September) and leatherbacks (May to September) (Figure 58). Large areas
of the coastal waters already have one or both longline and trawl gear restrictions, with a total
area of  85,9841mi2. Most the high use areas already have trawl and/or longline restrictions
provided by the current regulated fishing zones. Only 1 high use area (CP) does not currently
have trawl or longline protections over the majority of their area, and 5 high use areas (PB, CC,

85

PC, BS and SP) are
lacking pelagic and
bottom trawl or
longline restrictions.
The addition of
these restrictions in
high use area would
only expand the
current area of
longline and trawl
restrictions to 
91,113mi2. Trawl

Figure 58. Sea turtle high use areas. Loggerhead: Big Bend (BB), Port Charlotte (PC), Cape
Coral (CC), Bonita Springs (BS), Key West (KW) and Palm Bay (PB). Leatherbacks: South
Panhandle (SP) and Central Panhandle (CP).

and longline restrictions on each of the high use areas would have very little impact on the
commercial fishermen but provide safe nesting, foraging and breeding habitats for both
loggerheads and leatherback sea turtles.
Fishing closures over ever high use zone would provide the fullest protection to the
turtles that reside in those areas; however, this is not a realistic option given the possible impacts
this could have the commercial fishing industry. Enacting pelagic and bottom trawl and longline
closures is a far more realistic protection that would limit sea turtles bycatch interactions as
trawls and longlines restrictions have been associated with higher turtle relocation KD.

Spatial Considerations
The regulated fishing zones create clean and easy to follow boundaries for commercial
fisheries, they are not tailored for research purposes. The varying sizes of the zones and overlap

86

of the zones result in ‘on-the-water’ complexity that I did account for directly in this study. I will
therefore discuss the implications of these spatial factors on my findings.
Zone area can affect the overall mean and median KD values of both large and small
zones since hotspots (by definition) are relatively small compared to the study area as a whole.
Smaller zones, such as Pourtales Terrace HAPC (547.3mi2) that overlap with a hotspot (Figure
34) have fewer low KD values within the zone, resulting in a relatively high KD median (0.8)
and mean (1.4). Large zones, even with high KD value hotspots within their area, see the
opposite of this effect, as a large zone’s KD means and medians will be lower by virtue of the
areas outside the hotspots with low KD values. For Example, the East Florida Coast
(33319.9mi2) overlapped the majority of the largest loggerhead hotspot (maximum of 275.7) but
had a lower mean (8.8) and median (1.0) than many of the smaller zones (Figure 32). The
Pourtales Terrace HAPC and East Florida Coast had medians that were very close to one another
despite having drastically different levels of hotspot interactions, highlighting how size can
leverage the results a more detailed examination was beyond the scope of this study.
Many of the regulated fishing zones overlap with each other which creates an issue when
attempting to study the relationship between zone turtle relocation KD and zone gear restrictions.
Of the fishing zones that were analyzed, Atlantic zones had 17 distinct overlapping areas, with
15 for the Gulf of Mexico zones (Figures 59&60). Larger zone overlapped the most with other
zones. Given that the larger zones typically did not have the same gear restrictions thus when
they overlapped the zones would essentially create a separate area subject to both the zones’ gear
restrictions. Such spatial overlap of gear restrictions from two or more zones was not considered
in this analysis but could be an interesting next step. For additional information regarding each
zone and their corresponding gear restrictions see tables 2 and 3.

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Atlantic Regulated Fishing Zones Overlap
AU

EFC

AOCA

LPN

SMT

LPS

FKN
MS

CBCA

OB

PT

AU
EFC
AOCA
LPN
SMT
LPS
CBCA
FKN
MS
OB
PT

Figure 59. Atlantic Ocean regulated fishing zone overlaps with other zones. Yellow=overlap, white= no overlap and black= n/a
(same zone). Atlantic Unregulated (AU), Stetson-Miami Terrace HAPC (SMT), Charleston Bump Closed Area (CBCA),
Allowable Octocoral Closed Area (AOCA), Pourtales Terrace HAPC (PT), East Florida Coast (EFC), Longline Prohibited South
of 27 10'N (LPS), Longline Prohibited North of 27 10'N (LPN), Florida Keys National Marine Sanctuary (FKNMS) and Oculina
Bank HAPC (OB).

Gulf of Mexico Regulated Fishing Zone Overlap
RFSA-WC

BLP

UGoM

MG

RRFLR

RFSA-MS

Edges

SWFTC

TSS-N

RFSA-WC
BLP
UGoM
MG
RRFLR
RFSA-MS
Edges
SWFTC
TSS-N

Figure 60. Gulf of Mexico regulated fishing zone overlaps with other zones. Orange=overlap, white= no overlap and back= n/a
(same zone). Unregulated-Gulf of Mexico (UGoM), Reef Fish Longline Restriction (RFLR), Bottom Longline Prohibited (BLP),
Reef Fish Stressed Areas, FL West Coast (RFSA-WC), Reef Fish Stressed Areas, FL, AL and MS (RFSA-MS), Middle Grounds
HAPC (MG), The Edges (Edges), Southwest Florida Trawl Closure (SWFTC) and Tortugas Shrimp Sanctuary North (TSS-N).

88

Conclusion
Overlapped mapping of regulated fishing zones with turtle relocation KD hotspots in the
waters off the Florida coast demonstrates that zones with higher KD hotspots are not associated
with regulated fishing zones with higher gear restrictions in general. However, higher KD values
are associated with more longline and trawl restrictions specifically. 11 hotspots between
loggerheads and leatherbacks in both the Atlantic and Gulf of Mexico were identified.
Loggerhead relocation hotspots were particularly associated with the Oculina Bank HAPC and
Florida Keys National Marine Sanctuary zones in the Atlantic and Tortugas Shrimp Sanctuary
North zone in the Gulf of Mexico. Leatherbacks relocation hotspots were particularly associated
with the Edges and Reef Fish Stressed Areas, Florida, Alabama and Mississippi zones in the
Gulf of Mexico. All of these zones have longline and/or trawl restrictions, further supporting the
overall findings of this study stated above. This does not mean that turtles actively avoid areas
with lower restrictions of these two types of gear but shows a potential link between how
longlines and trawls affect the turtles, and the impacts they could have on the dispersal of habitat
usage in Florida.
Longlines and trawls have higher rates of bycatch interactions and mortality then the
other commonly used commercial fishing gear such as nets, dredges and pot and traps (Kot et al.,
2010; Epperly et al., 2002; FAC & FAR, 2023; MSC, 2023). This illustrates that higher uses of
these two gear types in areas with turtles could create a higher risk of bycatch, than in zones with
restrictions. On both a federal and state level gear modifications have been required, such as
turtle excluder devices (TED) on trawls as well as gangion length, hook type and size
modifications on longlines, to help reduce bycatch (USFWS & DOI, 2013). While these
regulations play a role in reducing bycatch it does not eliminate bycatch and longlines and trawls

89

continue to have higher bycatch rates (Finkbeiner et al., 2011). Given that many of the relocation
hotspots between both loggerheads and leatherbacks have mixed levels of longline and trawl
restrictions, it shows that the turtles have an elevated risk of bycatch in the Florida Coastal
waters.
Sea turtle conservation is an ever-evolving field of study, with many anthropogenic
aspects to address. This study allowed for a closer look to be taken at how commercial fishing
gear is associated with sea turtles, the risks they pose and provide possible mitigation methods.
The result of this study may only be a small piece of the puzzle of how to reduce sea turtle
bycatch, but it does show that gaining a greater understanding of interactions between
commercial fishing gear and sea turtle relocations provides a steppingstone to for future research.

90

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The Evergreen State College Masters Theses: Environmental Studies

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