British Columbia researcher says liver oil and meat trade threatens shark populations

Dulvy is among researchers around the world sounding the alarm about existential threats to deep-sea sharks and rays, driven by overfishing and international demand for shark meat and liver oil.

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Professor Nick Dulvy remembers when the northern cod fishery collapsed in 1992.

“That was nothing short of a social and economic disaster for Canada,” said Dulvy, a biology professor at Simon Fraser University.

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For Dulvy, who is the Canada Research Chair in marine biodiversity and conservation at SFU, and other researchers, the “notorious” events of that year offer historical lessons about unsustainable fishing practices that resonate to this day.

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Dulvy is among researchers around the world sounding the alarm about existential threats to deep-sea sharks and rays, driven by overfishing and international demand for shark meat and liver oil.

He helped write a study published Thursday in the journal Science, which outlines how international trade and fishing regulations are needed immediately to avoid “irreversible” consequences.

Much of the public’s attention is focused on more “charismatic” shark species, such as hammerheads, white sharks and mako sharks, but deep-sea species are threatened due to improvements in fishing technologies, Dulvy said.

“We are raising more and more awareness about coastal shark problems, and it has been much easier to gain public attention and (get) policymakers to make changes based on these more charismatic species,” he said. “But it’s very easy to forget what happens in the deep, and we hear a lot about mining in the deep ocean, but the reality is that the biggest threat to the deep ocean that we now know about is overfishing.”

As coastal waters are depleted around the world, the push to go deeper means shark and ray populations become “collateral damage” to fishing operations.

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Deep-sea shark species, he said, have a “little understood but important role in regulating deep ocean ecosystems.”

Deep-sea sharks are targeted for their liver oil and today the substance ends up in several consumer products, he said.

“Liver oil is flying under the radar,” Dulvy said. “If you ask anyone about it, they’ll never have heard of it, but the reality is we’ve probably all used it or ingested it.”

Shark liver oil is used in cosmetics and nutritional supplements, so-called “nutraceuticals” and even vaccines, Dulvy said.

“None of us really have a choice whether or not to use liver oil because the product is not labeled in any way,” he said.

Regulations to curb the trade in shark fins and stingray gills have seen progress, and Dulvy said now “is the right time to draw attention to the plight of deep-sea sharks due to the international trade in their oil. liver”.

“The shark liver oil trade has been understudied and overshadowed by the more visible global trade in shark and rhinoceros ray fins, devil ray gills, and meat,” the study says. “Shark liver oil is among the most widely used shark products.”

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The study describes how deep ocean species faced “very little threat” before 1970. But a shift “coincided with the arrival and expansion of most deep-sea fishing,” and the number of threatened species doubled. by far between 1980 and 2005.

The research concludes with a warning and a call to action to regulate the shark liver oil trade, which Dulvy said will allow future generations the opportunity to see some of these “supercooled organisms.”

“We have the evidence to act more proactively in the deep ocean and learn from the mistakes that have led to more than half of coastal and pelagic species being threatened,” the research article concludes.

“Effective precautionary actions are needed to ensure that the largest ecosystem on the planet maintains its biodiversity and that half of the world’s shark and ray species are sheltered from the global extinction crisis.”

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