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World Sea Turtle Day 2022: Here are 10 ways in which we can prevent them from becoming bycatch

www.downtoearth.org.in | June 16, 2022
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World Sea Turtle Day (June 16) recognises this amazing group of animals and the people who protect them. Many scientists, natural resource managers, local community members and other stakeholders work together to reduce threats to sea turtles.

For example, bycatch — the unintentional capture of non-target species in fisheries — is considered to be a major cause of sea turtle mortality through animals drowning or receiving injuries that reduce their movements and feeding.

Collaboration is needed to understand the problem and develop strategies that reduce the risk of sea turtle entanglement in fishing gear, while still maintaining nutrition, livelihoods, income and food security.

Ten advances from the last year alone, as described below, demonstrate how collaboration among very different groups of people is reducing bycatch and contributing to sea turtle conservation worldwide.

1. Tracking fishing vessels and turtles

A study in the Rio de la Plata, the estuary of the Parana, Paraguay and Uruguay rivers in South America, combined data from geographic position systems on fishing vessels with satellite transmitters on sea turtles.

The researchers identified when trawlers and sea turtles were most likely to be in the same space at the important fishing ground in the southwestern Atlantic Ocean.

This will help the fisheries management agencies of Argentina and Uruguay to develop a bi-national management and conservation strategy for sea turtles in the Rio de la Plata.

2. Adopting new technology

The fisheries industry can be reluctant to adopt new technology, due to its concerns about reduced catch and income and feeling that its perspective and expertise are overlooked.

This was the story in many countries when TEDs (turtle excluder devices/trawler efficiency devices) were introduced for trawl fisheries, but less so in Georgia, United States.

Researchers spoke with a variety of stakeholders in the fishing industry and reviewed fisheries documents to understand why the ‘Georgia jumper’, a locally developed TED, was adopted with few issues.

They found that its success was based on the engagement of commercial trawler fishers in the design of a TED that would allow sea turtles to escape from trawler nets, be less expensive than other models to purchase and be acceptable to the industry.

Fishers were regarded as valuable collaborators in the process, and the technology was accepted far more easily than in other locations.

3. Trialling new technology

A new technology, known as the soft-type turtle releasing device (Soft-TRD), was recently assessed to ensure that it allowed sea turtles to escape set nets.

Researchers from fisheries and industry in Japan worked with local fishers to test the device in outdoor tanks and the ocean and check that the diameter and design of the escape slit in the net were successful.

Video footage of turtles escaping from the net was used by researchers to understand the behaviour of turtles caught in the net and optimise the design of the escape slit so that turtles could successfully escape with minimal loss of fish catch.

4. Illuminating gillnets

Sea turtles may be able to avoid some fisheries gear if it is more visible. Research in the Gulf of Guinea in Ghana and the Baja California peninsula of Mexico shows that attaching green light-emitting diodes (LEDs) to gillnets reduced the number of sea turtles that were caught but had no effect on fish catch and market value.

Moreover, fishers in Ghana also thought the lights would prevent other fishing vessels from running into their nets, damaging nets and propellors alike, and fishers in Mexico reported that the LEDs reduced the average time they needed to retrieve and disentangle their nets.

5. Changing hook shape

Fishers from the pole and line tuna fishery in Vietnam compared the traditional Japan tuna hook (JT-hook) and circle-shaped hook (C-hook) to see if changes in fishing gear would reduce sea turtle bycatch.

Fishers using JT-hooks and C-hooks caught the same number of fish but hooked far fewer turtles on C-hooks. It was also easier for fishers to remove C-hooks from hooked turtles than JT-hooks.

A benefit for fishers was the increased size of tuna caught using the C-hooks trialled in this study, so there will be conservation and economic benefits for fishers that change their gear.

6. Voluntary logbooks to record essential information for conservation

Not all measures to reduce sea turtle bycatch need new technology. Fishers in the Gulf of Manfredonia, Italy, shared information about their geographic position and fishing depth and duration when sea turtles were caught in bottom trawlers.

Fishing and bycatch data allowed researchers to predict locations where and when turtles would be most vulnerable to capture and estimate the number of turtles likely killed by the entire fishery.

This information suggests seasonal closures or area-based conservation, depending on different factors, to minimise both the risk to turtles and the impact of conservation action on fishers.

7. Patterns of information sharing among fishers

Gillnet fishers in San Jose, Peru, answered a questionnaire that allowed researchers to understand how information is shared among members of the fishing community.

The study found that fishers did not share information about sea turtle bycatch and bycatch reduction in the same way that they shared information about other related topics, such as fisheries location and fisheries activity.

The researchers interpret this finding as an indicator for managers to engage in educational discussions with fishers in this community about sea turtle conservation status and levels of bycatch instead of assuming that fishers will share such information among themselves.

8. Analysing risk factors for bycatch turtles

Trawler fishers along the Italian coast of the South Adriatic Sea transferred sea turtles caught in their nets to a local sea turtle rescue centre for treatment and study by veterinarians and researchers and shared data about their fishing operations when turtles were caught.

Clinical data collected at the rescue centre was analysed to understand how to diagnose, treat, and manage bycatch turtles to improve survival rates.

Fishing data was analysed to identify trawling practices that could be adjusted to reduce the rate of mortality.

The study found that limiting the time turtles remain trapped underwater in trawl nets can improve outcomes for bycatch turtles. Further, fishers can alert turtle hospitals and rescue centres about bycatch turtles and aid in their transport for treatment.

Even turtles that appear healthy after being removed from fishing nets are at risk of dying, and the correct diagnosis and treatment is important for turtles to be successfully rehabilitated and released back to sea.

9. Releasing entangled turtles

A compensation scheme offered by the Mangrove Cell of the Maharashtra Forest Department and the Fisheries Department of Maharashtra rewards fishers who cut or damage their fishing gear to release sea turtles.

Fishers must provide the geographic coordinates, a photograph of the entangled animal, and a video showing its release when submitting their application form for compensation, which provides data on where sea turtles are found in coastal waters.

A recent report of the first ~2.5 years of data reveals four species of sea turtles have been captured by Maharashtrian fishers off the coasts of Gujarat, Maharashtra, and Goa.

A scheme such as this compensates fishers for their conservation efforts and provides conservation managers and researchers with data on the local species of sea turtles and their preferred habitats.

10. Reducing ghost gear

Abandoned, lost, or otherwise discarded gear from any fishery (commonly known as ‘ghost gear’) in the ocean can also entangle sea turtles.

Reducing the amount of ghost gear in the ocean will help reduce sea turtle mortality associated with fisheries.

A recent study at Masirah Island in Oman brought together fisheries academics, conservation professionals and government representatives to discuss a fisher behaviour that could be changed to reduce the amount of ghost gear and possible barriers to fishers changing this behaviour.

The group then designed interventions that might reduce the barriers to disposing of fishing gear in a responsible way and asked fishers to assess them.

Observations of fishers’ use of skip bins to dispose of their fishing gear showed low adoption of the behaviour.

The authors concluded that fishers should have been involved earlier in the project of understanding the issue, identifying barriers and benefits for fishers to change their behaviour, and designing the intervention strategy.

These examples show us the benefits of researchers, managers, and fishers collaborating to minimise the threats of fisheries to sea turtles while recognising the importance of fisheries and needs of fishers. This World Sea Turtle Day, take the time to appreciate their efforts so that you can enjoy both sea turtles and sustainable seafood.

-Prof. Andrea Phillott, Professor - Environmental Studies.