Juvenile Great White Sharks Are Dying In High Numbers Off The Coast Of California And Mexico

Photo by Alex Steyn on Unsplash

In a new study in the Journal of Applied Ecology, it has found that fishing was the largest cause of death for juvenile great white sharks off the western coasts of Southern California and Mexico.

From 2002 to 2016, researchers tagged white sharks with satellite tags that remotely sent information about the sharks, such as location and temperature. Of the 37 tagged sharks that died, only two died from natural deaths. One shark died and sank to the sea floor 63 days after tagging. The second was apparently consumed by a predator 36 days after being tagged.

The data from the study suggest juvenile mortality of white sharks mainly resulted from interactions with fisheries, whereas natural mortality was very rare.

Locations where juvenile white sharks were tagged and subsequently died from fisheries or natural mortality along the coast of California and Mexico, 2000–2016. Via Journal Of Applied Ecology

The deaths of the sharks were the result of drift gillnets, a controversially fishing method that often catches whatever swims in its way. Drift gillnets can be spread a mile long and hang as deep as 100 feet. The sharks die when they become entangled and cannot escape.

White sharks are protected in both Mexico and the United States from intentional capture but unfortunately, gillnets are allowed for non-protected species and the bycatch of white sharks cannot be prosecuted when caught this way.

Great white sharks have seen a resurgence in recent years off the western coast of North America due to stronger laws to protect the marine animals but researchers are not sure how the driftnets will impact the species number as a whole in the coming decades.

Fishing is the biggest threat to sharks globally, particularly in waters that are less regulated than the U.S and Mexico. The importance of sharks cannot be overstated due to them being a keystone species. Sharks are at the top of the food chain in virtually every part of every ocean. In that role, they keep populations of other fish healthy and in proper proportion for their ecosystem. Eco-systems in the past have collapsed due to the loss of sharks and in recent studies, areas that have had protections for sharks have not only seen shark species rebound, but almost every other species of marine life due to the balance sharks bring.

Due to the findings of the research, better practices of releasing sharks immediately must be a focus or lawmakers need to completely ban the use of drift gillnets completely.

In response to undercover footage taken of the drift gillnet industry, lawmakers have recently proposed federal legislation to end their use off the American coasts entirely. Senators Dianne Feinstein, Kamala Harris and Shelley Moore Capito introduced the Driftnet Modernization and Bycatch Reduction Act, which is intended to phase out the use of these nets from the U.S.

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