Arlington, Virginia — Millions of sea turtles have become the unintended victims of a failure to properly manage the worlds' fisheries, with more and more of their habitats clogged with hooks and nets, an important new report revealed today.
The report — the first ever global assessment of sea turtle bycatch in the three major types of fishing gear: gillnets, longlines, and trawls — highlights vast ocean regions where little about bycatch rates is known, and where urgent conservation action to reduce bycatch is necessary to prevent the extinction of these ancient, endangered animals.
The report, which appears this week in the journal Conservation Letters was conducted by Conservation International (CI) in partnership with Duke University's Project GloBAL (Global By-catch Assessment of Long-lived Species), and clearly shows the links between increased fishing gear in regions and the increase in accidental capture of sea turtles.
Bycatch occurs when fisheries use indiscriminate gear such as longlines with thousands of baited hooks, or nets that inadvertently snag animals other than what they are intended to catch. Sea turtles, along with sharks, dolphins, and albatrosses, are among the most frequently accidentally captured. Air-breathing reptiles, sea turtles often perish as a result of drowning in nets or swallowing sharp J-shaped hooks which can become lodged in the soft tissue of turtles' throats and stomachs, causing severe and often grave injuries.
In their report titled: "Global Patterns of Marine Turtle Bycatch", Dr. Bryan Wallace of CI, and Dr. Rebecca Lewison of San Diego State University, with several co-authors from Duke University's Center for Marine Conservation, investigated the impact of bycatch on sea turtles around the globe from 1990-2008. Their findings show that tens of thousands (~85,000) of marine turtles have been reported as bycatch in the past twenty years, but Wallace and colleagues stress that actual numbers are likely to be significantly higher.
Dr. Wallace, the Science Advisor for CI's Sea Turtle Flagship Program said: "Because the reports we reviewed typically covered less than one percent of all fleets, with little or no information from small-scale fisheries around the world, we conservatively estimate that the true total is probably not in tens of thousands, but in the millions of turtles taken as bycatch in the past two decades."
Six of the seven marine turtle species are currently categorized as Vulnerable, Endangered, or Critically Endangered globally by the International Union of Conservation of Nature's (IUCN) Red List. They include loggerheads, leatherbacks, hawksbills, Olive Ridleys, Kemp's Ridleys and green sea turtles; the flatback, an endemic to Australia, is currently categorized as Data Deficient.
Sea turtles are highly migratory animals that cover vast areas of ocean between nesting and feeding grounds, traveling thousands of miles each year and traversing international boundaries. Their broad distributions expose them to several threats, including directed capture for their meat and collection of eggs, destruction of nesting beaches, pollution of the ocean, and climate change. However, bycatch is the most serious, acute threat to sea turtle populations around the world.
The global data review revealed that the highest reported bycatch rates for longline fisheries occurred off Mexico's Baja California peninsula, the highest rates for gillnet fishing took place in the North Adriatic region of the Mediterranean and the highest rates for trawls were found off the coast of Uruguay.
However, when bycatch rates and amounts of reported fishing activity for all three fishing gear types were combined and compared, four regions emerged as the overall most urgent conservation priorities: the Mediterranean, the Eastern Pacific, the Southwest Atlantic, and the Northwest Atlantic.
In the Mediterranean Sea, where more than 20 countries fish in the same ocean basin for species like bluefin tuna and swordfish, a lack of integrated management has led to some of the highest concentrations of longline fishing and trawling around the globe, and consequently, some of the highest sea turtle bycatch rates in the world.
In the Eastern Pacific — which stretches from Baja California, to Patagonia, Chile and hosts critical nesting and breeding grounds for the leatherback and Olive ridley sea turtles — populations of leatherback and hawksbill have nearly collapsed, owing in part to bycatch in large and small-scale fisheries which deploy large numbers of longlines, gillnets and shrimp trawls in both the high-seas and near shore.
Other regions highlighted as urgent conservation priorities in the report include the Southwest Atlantic and Northwest off the eastern United States, home to one of the world's largest loggerhead turtle populations, but where high numbers of longline and trawl fisheries also contribute to high incidents of bycatch.
"We have only begun to scratch the surface about the realities of sea turtle bycatch," said study researcher Dr. Wallace. "Our review revealed important data gaps in areas where small-scale fisheries operate, especially Africa, the eastern Indian Ocean and Southeast Asia. These regions and fisheries are urgent priorities for enhanced monitoring and reporting effort so that we can fill in some blanks about turtle bycatch."
To lower sea turtle bycatch rates, and improve overall ocean health, Conservation International's Global Marine Division has recommended several strategies:
- Regional governance: establish Marine Protected Areas similar to those CI has successfully supported in the Eastern Pacific Tropical Seascape (ETPS) and Bird's Head and Sulu Sulawesi Seascapes of Indonesia.
- Sustainable fisheries reform: including seasonal and time-area closures to control fishing activity in turtle migration areas as well as catch-shares, which place quotas on fishing efforts and reduce the race for fish
- Selective gear modification: the continued use of circle hooks, as well as the widespread implementation of Turtle Excluder Devices (TEDs), which serve as escape hatches for sea turtles caught in shrimp trawls.
- Responsible seafood consumption: Consumers are encouraged to use wallet guides (available from the Blue Ocean Institute and others) and resources like FishPhone, to learn more about turtle-friendly seafood choices.
Coordinated implementation of these strategies will have dramatic effect on the viability and persistence of our oceans and of sea turtles, because they, like other large, highly migratory, charismatic marine animals, are bellwethers of ocean health.
"Sea turtles are sentinel species of how oceans are functioning. The impacts that human activities have on them give us an idea as to how those same activities are affecting the oceans on which billions of people around the world depend for their own well-being." said Dr. Wallace. "Our hope is that this study gives governments and fisheries alike another impetus for bolstering on-going efforts to reduce sea turtle bycatch and to promote more sustainable fishing practices as soon as possible."
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Notes to the editors:
Conservation International (CI): Building upon a strong foundation of science, partnership and field demonstration, CI empowers societies to responsibly and sustainably care for nature for the well-being of humanity. With headquarters in Washington, DC, CI works in more than 40 countries on four continents. For more information, visit www.conservation.org.
Duke University Center for Marine Conservation: an interdisciplinary consortium at Duke's Nicholas School of the Environment focusing on research, education, and outreach in marine conservation. Project GloBAL (Global Bycatch Assessment of Long-lived Species) is a joint venture between Duke and Blue Ocean Institute that aims to characterize the bycatch of marine mammals, seabirds, and sea turtles.
Blue Ocean Institute Fishphone & Wallet Guides: Blue Ocean Institute uses science, art, and literature to inspire a closer bond with nature, especially the sea. To request a free seafood wallet guide from anywhere in the world, visit: www.blueocean.org. Within the continental U.S., FishPhone is Blue Ocean's sustainable seafood text messaging service that instantly puts sustainable seafood information at your fingertips. To find out about your seafood choice, text 30644 with the message FISH and the name of the fish in question.