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Turtle Caught Twice In Fishing Nets Demonstrates Two Main Threats For Marine Life

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Rachael Funnell

Social Editor and Staff Writer

clockJun 16 2021, 13:15 UTC
"Thunderbird" The Turtle Caught Twice In Fishing Nets Demonstrates Dual Threat For Ocean Life

Thunderbird survived a close call with ghost fishing gear, only to get caught up in fishing bycatch just a year later. Image credit: Miquel Gomina

Meme after meme has captured the perilous life of sea turtles, which start out with a fraught race to the ocean only to spend the rest of their lives in a sea plagued by human waste. On World Sea Turtle Day, it’s important to not just celebrate the many ways in which sea turtles enrich our oceans (and meme content), but to also shine a light on the struggles they face – many of which we can do something about.

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The tale of an unlucky female turtle named “Thunderbird” has demonstrated exactly how hard it is to stay alive in the modern ocean. Thunderbird was first picked up by the Save the Med Foundation found tangled in ghost fishing gear in the Mediterranean in July 2020. Ghost fishing gear is the phrase used to describe discarded bits of rope or nets from the fishing industry and is considered by the World Wide Fund for Nature (WWF) to be the deadliest form of marine plastic (this guy spends his days freeing whales from such material).

world sea turtle day
Thunderbird was found wrapped in ghost fishing gear. Image credit: Palma Aquarium

Dr David March of the Universities of Exeter and Barcelona explained that Thunderbird was captured, treated, and tagged following her rescue, before being released in August of the same year. The tracking device meant March and colleagues were able to track Thunderbird’s epic journey of 6,000 kilometers (3,730 miles) through the western Mediterranean and the waters off West Africa.

For a brief time, Thunderbird’s signals became erratic as she passed through the Alboran Sea. This was a tense time for those monitoring its progress, as the challenging waters here are home to strong currents and a high density of marine traffic, increasing the risk of collision.

world sea turtle day
Thunderbird was released, plastic-free, by Save the Med in 2020. Image credit: Save the Med

Seemingly unscathed, Thunderbird pulled through and swam up-current out of the Mediterranean in November 2020, through the Gibraltar Strait and along the West African coast. The satellite data across Thunderbird’s journey revealed that while she spent most of the time at the surface in the Mediterranean, she favored the sea bottom along the West African coast making regular dives. Unfortunately, it was at this point that Thunderbird’s luck once again took a turn for the worse.

Image credit: Dr David March

"In February this year, the turtle was off Senegal when we stopped receiving regular updates from the tag," Dr March said. "Then the final signal on 17 March was on land, near the main harbour in Dakar.” To try and suss out what had happened, the team used the Global Fishing Watch portal to look for any overlaps between Thunderbird’s known final movements and the activity of fishing vessels. This revealed that her last dive did indeed coincide with a fishing region regularly used by trawlers.

"All this suggests the turtle was bycaught by a fishing vessel and taken back to the port,” said March. “We don´t know if Thunderbird was released alive after capture or died as consequence of the bycatch event.

"The epic journey of this turtle illustrates two of the major threats that many marine species face – entanglement in ghost fishing gear, and bycatch in industrial fisheries. We must urgently address both issues to limit their impact on a wide range of marine species and ecosystems."


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Nature
  • conservation,

  • bycatch,

  • ghost fishing nets

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