“During long, humid walks along Costa Rica’s Playa Grande, patrolling in vain for signs of the few remaining leatherback turtles (Dermochelys coriacea) in the eastern Pacific Ocean,” says Bryan Wallace, Science Advisor at Conservation International (CI), “I imagined what the beach must have looked like 20 years before, when there were so many of these gentle giants crawling around, throwing sand and laying eggs, that the local people referred to them as hormigas – ants. It’s amazing that relatively short periods of intense fisheries bycatch and egg harvest has nearly wiped out this population.”
The study estimates that in the last 20 years, about 85,000 sea turtles were reported as bycatch. However, due to massive under-reporting of these activities–particularly among small-scale fisheries–the actual estimate of sea turtle bycatch casualties is estimated to number in the millions.
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“Global Patterns of Marine Turtle Bycatch,” a recent paper coauthored by Wallace and his colleagues from Duke University and San Diego State University, suggests that fisheries bycatch may pose the biggest threat to marine turtle species worldwide.
IN DEPTH: Sea Turtle Flagship Program
The study underscores the need for immediate action–not only to curb the loss of these unique species, but also to maintain fishery and ocean health across the globe.
An Ancient Species Under Threat
While sea turtles have been swimming our oceans for more than 100 million years, their very short history with humans is casting their future into doubt. Six out of seven species of turtle are currently listed as Vulnerable, Endangered or Critically Endangered by the IUCN Red List.
Sea turtles are threatened by a variety of factors, but fisheries bycatch – the unintentional capture of non-target species in fishing gear – is the most acute threat to sea turtle populations today. During many fishing operations, turtles regularly get caught in nets or hooked on lines, where they often sustain serious injury or drown. The turtles’ long lifespan and slow reproduction rates make it more difficult for populations to recover from these losses.
The global decline of sea turtles threatens much more than the turtles themselves; in addition to its larger ecological implications, the high number of turtles caught as bycatch also impacts many poor fishing communities, as fishermen lose time and money repairing fishing gear damaged by sea turtles and other bycatch species.
A Global View of Turtle Bycatch
The paper was published this week in the scientific journal Conservation Letters. The researchers compiled and synthesized sea turtle bycatch reports from around the world between 1990 and 2008.
It is the first global study that compiles bycatch data from the three most prominent categories of fishing gear: gillnets, longlines and trawls.
Among the findings, the study estimates that in the last 20 years, about 85,000 sea turtles were reported as bycatch. However, due to massive under-reporting of these activities–particularly among small-scale fisheries–the actual estimate of sea turtle bycatch casualties is estimated to number in the millions.
FEATURE: Communities and Sea Turtles
Regions with the highest bycatch rates varied by type of fishing gear, and include coastal regions of:
- Mexico’s Baja California for longlines,
- Uruguay for trawl fishing and
- the North Adriatic region of the Mediterranean Sea for gillnets.
Based on the information available, the study’s authors have identified several regions that should be the highest priority for efforts to reduce sea turtle bycatch: the eastern Pacific, Mediterranean Sea and western Atlantic.
However, Wallace emphasizes that one of the study’s major findings was just how little recorded data exists. “Even the most well-observed fleets still only have about 1-5 percent coverage – at best – and that’s before we even begin to consider bycatch in small-scale fisheries. Ninety-nine percent of the world’s fishers operate in these artisanal fisheries around the world, which are almost completely unmonitored and unreported.”
Taking Action Now
Sea turtles are among the most migratory animals on Earth, many of them crossing thousands of miles of ocean – and international borders – in a single season. For this reason, efforts to curtail sea turtle bycatch will have to coordinate across countries, sectors and communities – from the crews of commercial tuna boats to artisanal fishers in wooden canoes to fish lovers in four-star restaurants.
Recent research and technological advancements have shown that there are relatively simple, fairly cheap measures that fishers can take to reduce turtle bycatch without limiting fish catch. The study’s authors recommend the adoption of turtle-friendly practices outlined by the UN’s Food and Agriculture Organization (FAO), including:
- the use of turtle exclusion devices (TEDs) in trawl nets, which act as trapdoors to allow turtles to escape once they are caught;
- replacing “J” hooks on longlines with circle hooks, which are too large for turtles to swallow; and
- substituting squid bait with fish bait on hooks – research has shown that most turtles consume fish by taking smaller bites, as opposed to squid, which they swallow whole, including the hook it’s on. By eliminating squid bait, the turtles are less likely to swallow hooks.
The paper’s authors also suggest that consumers support seafood from responsible sources, which will encourage more sustainable practices throughout the industry.
TAKE PART: Learn more about the actions you can take to help protect Sea Turtles and other marine life.
The Bigger Picture for Marine Conservation
Conducting detailed research on sea turtles and other species is an important part of CI’s larger plan for worldwide ocean conservation – a plan that includes a global index for ocean health, better ocean governance and sustainable fisheries.
“Reduction, or ideally elimination, of bycatch of endangered species is a must if fisheries are to become sustainable”, says Sebastian Troëng, Vice President for Marine Conservation at CI. “This global study shows us where urgent action is needed to make fisheries more sustainable and will help our efforts to sustain ocean health.”
READ MORE: Turning Science into Sustainable Fishing