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A Brighter Light on Bycatch

Illuminated gillnets may become an important part of preventing marine turtle bycatch.

Fishermen with net

Gillnet fishing is one of the most common forms of fishing in the world. The gear is great at catching shrimp or fish, but unfortunately it also catches many non-targeted species, such as loggerhead or green turtles. In fact, this accidental “bycatch” is among the greatest threats to the survival of many marine turtle populations.

To address this global problem, WWF created the International Smart Gear Competition, calling on ‘backyard’ inventors to put forth innovative solutions to reduce bycatch. In 2011, the competition yielded a partial solution to the problems caused by gillnets.

LED gillnet light

As gillnet mesh is very hard to see underwater, the team hypothesized that if nets were more visible, then turtles could avoid swimming into them. Their design (“Turtle Lights for Gillnets”) uses widely available fishing lights (LED or chemical lightsticks) to illuminate gillnets. The lights allow the turtles to detect the net and avoid becoming entangled in it.

Initial tests on gillnet fishing in the Gulf of California yielded encouraging results: there was a 40 percent decrease in the number of green turtles caught in nets and an increase in the target catch. Last summer, WWF conducted additional testing in the Eastern Pacific Ocean at a location where fisheries overlap with endangered loggerhead turtle feeding areas. Nighttime results showed that the Turtle Lights once again reduced turtle bycatch, with 50 percent fewer turtles caught in illuminated nets compared to regular nets.

Overall, these results suggest that illuminated gillnets may be an important part of preventing marine turtle bycatch. WWF hopes to continue to support this promising work, and also to fund some testing with critically endangered leatherback turtles. We also look forward to the next “smart” innovation to protect marine species from unintended harm.

This story was originally published in FOCUS, WWF’s bi-monthly member newsletter. Learn more about the benefits of membership.

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