Sharks, turtles and other sea creatures face greater risk from industrial fishing than previously thought − we estimated added pressure from ‘dark’ fishing vessels

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Heather Welch, University of California, Santa Cruz

(THE CONVERSATION) My colleagues and I mapped activity in the northeast Pacific of “dark” fishing vessels – boats that turn off their location devices or lose signal for technical reasons. In our new study, we found that highly mobile marine predators, such as sea lions, sharks and leatherback sea turtles, are significantly more threatened than previously thought because of large numbers of dark fishing vessels operating where these species live.

While we couldn’t directly watch the activities of each of these dark vessels, new technological advances, including satellite data and machine learning, make it possible to estimate where they go when they are not broadcasting their locations.

Examining five years of data from fishing vessel location devices and the habitats of 14 large marine species, including seabirds, sharks, turtles, sea lions and tunas, we found that our estimates of risk to these animals increased by nearly 25% when we accounted for the presence of dark vessels. For some individual predators, such as albacore and bluefin tunas, this adjustment increased risk by over 36%. The main hot spots were in the Bering Sea and along the Pacific coast of...