Leatherback Turtle

Species: 

Dermochelys coriacea

IUCN Status: 

Critically Endangered
Photo: Mass DMF, taken under NOAA 50 CFR 222.310 with authorization of the ESA

The worldwide decline in leatherback turtles has been caused, in part, by bycatch in fisheries. Leatherback turtles most often entangled or hooked externally in pelagic longline fisheries (Garrison 2003), but are capable of swimming to the surface to breathe (Witzell and Cramer 1995).  Although not all incidental captures lead to mortality, the number of leatherbacks caught each year is very high and post release mortality rates are unknown. Lewison et al (2004) estimated that the global longlining fleets took 50 to 60,000 leatherbacks in 2000. 

Leatherbacks are also taken in trawl fisheries and entangled in gillnets and pot or trap lines.  Mortality rates are higher in trawl and gillnet fisheries because entangled turtles are unable to swim to the surface to breathe. Leatherback have been found entangled in fixed gear in Canada and in US waters from Maine to New York (Dwyer et al 2003). An estimated 3000 leatherbacks interacted with artisanal gillnet fisheries off Trinidad in 2000, where mortality rates were between 28 and 34% (Lee Lum 2003).

One method employed to protect leatherbacks in the North Atlantic is reducing interactions between the turtles and pelagic longline fisheries through an area closure of the Northeast Distant (NED) reporting area.  Circle hooks have also successfully decreased bycatch rates of leatherback turtles in some longline fisheries (Gilman et al 2011).

References


Gilman, E, D Kobayashi, T Swenarton, N Brothers, P Dalzell, and I Kinan-Kelly. 2011. REducing sea turtle interactions in the Hawaii-based longline swordfish fishery. Biological Conservation 139: 19-28.

Lewison, RL, SA Freeman, and LB Crowder. 2004. Quantifying the effects of fisheries on threatened species: the impact of pelagic longlines on loggerhead and leatherback sea turtles. Ecology Letters 7(3): 221-344.

Bycatch Threat: 

Longlines, gillnets, trawls, pot/traps

Population: 

Decreasing
Circumglobal in tropical to sub-polar waters

Type: 

Reptile

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Related Field Studies

Location Gear Technique Species Results Catch Effect on Target Catch Type Reference
San Jose, Salaverry, Ancon, Peru Gillnets Visual deterrents Small Cetaceans (maximum length < 7.5 meters), Seabirds, Sea Turtles Bycatch probability per set was reduced by up to 74.4% for sea turtles and 70.8 for small cetaceans in comparison to non-illuminated nets. For seabirds, nominal BPUE decreased by 84% in the presence of LEDs. Elasmobranchs, tuna, dolphinfish No effect Field study in the wild An illuminating idea to reduce bycatch in the Peruvian small-scale gillnet fishery.
Atlantic and Indian Ocean Surrounding nets Sea Turtles Purse seine fisheries have very low impact on sea turtles. N/A N/A Summary study Marine turtle interaction with purse seine fishery in the Atlantic and Indian Oceans: lessons for management
Gulf of Maine Traps At-call pop-up buoys, Timed release Mammals, Eubalaena glacialis (NA Right whale), Sea Turtles Not tested Lobster N/A Study in the lab Rope-less fishing technology development
Kuwait Trawls Excluder devices Bony Fishes, Sea Turtles FE significantly reduced bycatch catches Shrimp FE significantly reduced shrimp catches Field study in the wild An assessment of bycatch reduction devices in Kuwait's shrimp trawl fishery
Kuwait Trawls Excluder devices Bony Fishes, Sea Turtles SMT significantly reduced bycatch Shrimp SMT caught significantly larger shrimp but not significantly fewer shrimp Field study in the wild An assessment of bycatch reduction devices in Kuwait's shrimp trawl fishery
Kuwait Trawls Excluder devices Bony Fishes, Sea Turtles TED use resulted in no interactions with sea turtles or large animals; did not significantly reduce bycatch catches Shrimp Did not significantly reduce shrimp catches Field study in the wild An assessment of bycatch reduction devices in Kuwait's shrimp trawl fishery
Review Gillnets Low profile gillnet Large Cetaceans (maximum length > 7.5 meters), Small Cetaceans (maximum length < 7.5 meters), Pinnipeds, Seabirds, Sea Turtles Summary study Reducing bycatch in gillnets: A sensory ecology perspective
Pacific Hooks-and-Lines Circle hooks Sea Turtles Reduced sea turtle interactions likely due to use of circle and not J hooks Tuna All tuna species had higher catches rates when wider circle hooks were used. Shortfin spearfish and striped marlin catch rates were lower with circle hooks. No differences in average length between hook types. Field study in the wild Hawaii longline tuna fishery temporal trends in standardized catch rates and length distributions and effects on pelagic seamount ecosystems
Tropical northeast Atlantic Hooks-and-Lines Circle hooks Sea Turtles Hardshell turtle interactions were reduced when both circle hook styles and mackerel bait were used. Swordfish Non reported Field study in the wild Effects of hook and bait in a tropical northeast Atlantic pelagic longline fishery: Part I - Incidental sea turtle bycatch
Pacific Ocean Hooks-and-Lines Sea Turtles n/a tuna and billfish n/a Field study in the wild Predicting bycatch hotspots for endangered leatherback turtles on longlines in the Pacific Ocean
Eastern Pacific Ocean Hooks-and-Lines Circle hooks Sea Turtles Decreased hookings of sea turtles Mahi-mahi and tunas, billfishes, sharks (TBS) Not consistent Field study in the wild Circle hooks: developing better fishing practices in the artisanal longline fisheries of the Eastern Pacific Ocean
Costa Rica Hooks-and-Lines Sharks, Skates/Rays, Bony Fishes, Elasmobranchs, Sea Turtles mahi-mahi, tunas, marlins, sharks Summary study Impact of Costa Rican longline fishery on its bycatch of sharks, stingrays, bony fish and olive ridley turtles (Lepidochelys olivacea)
Baja California Sur, Mexico Gillnets Visual deterrents Sea Turtles Reduced capture by 39.7% Flounder, others No significant difference in catch rates Field study in the wild Developing ultraviolet illumination of gillnets as a method to reduce sea turtle bycatch
Southwest Atlantic Hooks-and-Lines Circle hooks Seabirds, Elasmobranchs, Sea Turtles American style longlines - no significant difference in catch rates for blue or porbeagle sharks, seabirds or sea turtles. Spanish style longline - significant decrease in pelagic stingray catch rates on circle hooks, no significant differences in catch Tuna Albacore catches increased with circle hooks on both types of longline. Shortfin mako shark catch rates increased with circle hooks on the American style longlines. Field study in the wild Circle hook performance in the Uruguayan pelagic longline fishery
Chesapeake Bay, United States Traps Alternative leader design Sea Turtles Significantly reduced sea turtle interactions Atlantic thread herring, butterfish, Atlantic croaker, weakfish No difference Field study in the wild Evaluation of a pound net leader designed to reduce sea turtle bycatch
Chesapeake Bay Surrounding nets Alternative leader design Sea Turtles . During the study, 21 sea turtles interacted with the control net, while only 1 interaction with the experimental net occurred, which was a significant difference. Finfish There was no significant difference in the harvest weight or size selectivity of finfish between the two nets (control and experimental) Field study in the wild Evaluation of a pound net leader designed to reduce sea turtle bycatch
Baja California Sur, Mexico Gillnets Visual deterrents Sea Turtles Chemical light sticks reduced green turtle bycatch by 60% Flatfish and elasmobranchs No effect Field study in the wild Developing visual deterrents to reduce sea turtle bycatch in gill net fisheries
Baja California Sur, Mexico Gillnets Visual deterrents Sea Turtles LED lights reduced green turtle bycatch by 40% Flatfish and elasmobranchs No effect Field study in the wild Developing visual deterrents to reduce sea turtle bycatch in gill net fisheries
Baja California Sur, Mexico Gillnets Visual deterrents Sea Turtles Reduced green turtle bycatch by 54% Flatfish and elasmobranchs Reduced target catch by 45% and catch value by 47% Field study in the wild Developing visual deterrents to reduce sea turtle bycatch in gill net fisheries
eastern Pacific Ocean Hooks-and-Lines Circle hooks Bony Fishes, Elasmobranchs, Sea Turtles Significant differences between J and circle hook size 15 and between J and circle hook size 16 were found in the bycatch species group (all species grouped together). Chub mackerel bait caught the sharks. Tuna No significant differences in catch rates of the target species were found between hook types. The highest catch rates for tunas were found on circle hooks size 15. Squid and jack mackerel bait had the highest catch rates for tunas. Field study in the wild Comparison of circle hook and J hook catch rate for target and bycatch species taken in the Korean tuna longline fishery during 2005-2006
Northern Australia Trawls Excluder devices Sea Turtles Upward facing TED's reduced sea turtle bycatch by 99% Prawns Reduced the proportion of soft and damaged prawns by 35.8% and reduced catches of tiger prawns by 6.3% Field study in the wild The impact of turtle excluder devices and bycatch reduction devices on diverse tropical marine communities in Australia's northern prawn trawl fishery
Australia Hooks-and-Lines Deep sets Sea Turtles None reported Bigeye tuna Weighted longlines had a slightly higher overall CPUE (1.3 fish/100 hooks) compared to traditional longlines (1.08 fish/100 hooks) and caught more bigeye (0.95 fish/ 100 hooks) than traditional longlines (0.56 fish/100 hooks). Catch rates were not very Field study in the wild Trial setting of deep longline techniques to reduce bycatch and increase targeting of deep-swimming tunas
Northern Australia Trawls Excluder devices Sea Turtles JT 2 design did not prevent capture of sea turtles Prawns Caught 5.2% more tiger prawns and 6.9% more endeavour prawns than standard net Field study in the wild At-sea testing and assessment of the John Thomas bigeye turtle excluder device as an approved TED for Australia's northern prawn fishery
Northern Australia Trawls Excluder devices Sea Turtles JT 1 design did not prevent capture of sea turtles Prawns Caught 6.6% more tiger prawns and 10.5% more endeavour prawns than standard net Field study in the wild At-sea testing and assessment of the John Thomas bigeye turtle excluder device as an approved TED for Australia's northern prawn fishery
US Mid Atlantic Dredge Excluder devices Sea Turtles Reduced interactions between hard shelled sea turtles and dredge gear Scallop None reported Field study in the wild Interactions between sea turtles and dredge gear in the U.S. sea scallop (Placopecten magellanicus) fishery, 2001-2008
Chesapeake Bay, Virginia Traps Alternative leader design Sea Turtles Significant reduction of sea turtles bycatch Finfish, including: Atlantic tread herring (Opisthonema oglinum), harvestfish (Peprilus alepidotus), butterfish (Peprilus triacanthus), Atlantic croaker (Micropogonias undulatus) and weakfish (Cynoscion regalis) No difference for four species, increased catch of a fifth Field study in the wild Performance in 2004 and 2005 of an alternative leader design on the bycatch of sea turtles and the catch of finfish in Chesapeake Bay pound nets, offshore Kiptopeake, VA
Northern Australia Trawls Excluder devices Elasmobranchs, Invertebrates, Sea Turtles Little effect Prawns Little effect Field study in the wild The impact of turtle excluder devices and bycatch reduction devices on diverse tropical marine communities in Australia's northern prawn trawl fishery
Northern Australia Trawls Excluder devices Sea Turtles Downward facing TEDs reduced sea turtle catches by 100% Prawns Reduced the proportion of soft and damaged prawns by 63.2% and reduced catches of tiger prawns by 6.3% Field study in the wild The impact of turtle excluder devices and bycatch reduction devices on diverse tropical marine communities in Australia's northern prawn trawl fishery
Northwest Africa Trawls Excluder devices Sea Turtles Allowed 100% of sea turtles to escape Sardinella None reported Field study in the wild Bycatch and release of pelagic megafauna in industrial trawler fisheries off Northwest Africa
Western Australia Trawls Excluder devices Sea Turtles Reduced catches rates from 26.2 (catch per 1000 shots) to 0.9 Red emperor, scarlet perch, spangled emperor, Rankin cod, blue spot emperor, rosy threadfin brea, flagfish, frypan snapper, red snapper and goldband snapper None reported Field study in the wild Evaluation of exclusion grids to reduce the bycatch of dolphins, turtles, sharks and rays in the Pilbara trawl fishery
Northern Australia Trawls Excluder devices Sea Turtles Reduced sea turtle catches by 100% Prawns Reduced the proportion of soft and damaged prawns by 41.6% and reduced catches of tiger prawns by 6.5% Field study in the wild The impact of turtle excluder devices and bycatch reduction devices on diverse tropical marine communities in Australia's northern prawn trawl fishery
Pamlico Sound, North Carolina Gillnets Sub-surface sets (gillnets) Sea Turtles Reduced incidental capture of sea turtles and bycatch species flounder Reduced catches of flounders Field study in the wild Low-profile gillnet testing in the deep water region of Pamlico Sound, NC.
Pamlico Sound, North Carolina Gillnets Low profile gillnet Sea Turtles Reduced incidental capture of sea turtles and bycatch species flounder Reduced catches of flounders Field study in the wild Low-profile gillnet testing in the deep water region of Pamlico Sound, NC.
USA Mid-Atlantic Dredge Excluder devices Sea Turtles Reduced serious injury sea scallops not reported Field study in the wild Evaluation of a modified scallop dredge's ability to reduce the likelihood of damage to loggerhead sea turtle carcasses
off Hawaii Hooks-and-Lines Circle hooks Sea Turtles Highly significant reduction in the proportion of turtles that swallowed hooks Swordfish Swordfish catch increased by 16%, tuna catch decreased by 50%, and mahi-mahi, opah, and wahoo catch decreased by 34% Field study in the wild Reducing sea turtle interactions in the Hawaii-based longline swordfish fishery
off Hawaii Hooks-and-Lines Circle hooks Sea Turtles Leatherback turtle capture rates declined by 83% and loggerhead capture rates declined by 90% Swordfish Swordfish catch increased by 16%, tuna catch decreased by 50%, and mahi-mahi, opah, and wahoo catch decreased by 34% Field study in the wild Reducing sea turtle interactions in the Hawaii-based longline swordfish fishery
Costa Rica Hooks-and-Lines Dyed bait Sea Turtles Did not reduce bycatch Swordfish and tuna Field study in the wild Food color and marine turtle feeding behavior: Can blue bait reduce turtle bycatch in commercial fisheries?
Gulf of Mexico Trawls Excluder devices Sea Turtles Reduced bycatch shrimp Catch varied by TED configuration and location Field study in the wild Loggerhead turtle, finfish and shrimp retention studies on four excluder devices (TEDs)
Atlantic and Gulf of Mexico Trawls Excluder devices Sea Turtles Reduced bycatch shrimp Field study in the wild Incidental capture of sea turtles in shrimp trawls with and without TEDs in U.S. Atlantic and Gulf Waters
Azores Hooks-and-Lines Circle hooks Sea Turtles Swordfish and blue shark Increased target catch Field study in the wild Experiment to Evaluate Gear Modification on Rates of Sea Turtle Bycatch in the Swordfish Longline Fishery in the Azores
Chesapeake Bay Traps Trap guards (T-bars, otter guards) Sea Turtles Reduced turtle bycatch Crab No impact on number or size of crabs Field study in the wild Impact of a bycatch reduction device on diamondback terrapin and blue crab capture in crab pots
Hawaii Hooks-and-Lines Deep sets Sea Turtles Reduced bycatch Bigeye tuna Increased target catch Field study in the wild
Gulf of Maine Dredge Excluder devices Sea Turtles Eliminated bycatch Scallop Slightly reduced target catch Field study in the wild Industry trials of a modified sea scallop dredge to minimize the catch of sea turtles