B.C. researcher says liver oil, meat trade threaten deepwater shark populations

Prof. Nick Dulvy recalls when the northern cod fishery collapsed in 1992. 

"That was nothing short of a social and economic disaster for Canada," said the biology professor at Simon Fraser University in Burnaby, B.C.

For Dulvy, 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. 

He is among researchers from around the world who are sounding the alarm about existential threats to deepwater sharks and rays, driven by overfishing and the international demand for meat and shark liver oil. 

Dulvy helped author a study published Thursday in the journal Science that outlines how international trade and fishing regulations are needed immediately to prevent "irreversible" consequences.

A lot of public attention goes to more "charismatic" shark species such as hammerheads, great whites and makos, but deep-ocean species are under threat due to improvements in fishing technologies, Dulvy said.

"Increasingly, we're raising awareness of coastal shark issues as well, and it's been much easier to gain public attention and [get] policymakers to make change based on these more charismatic species," he said.

"But it's very easy to forget what's going on in the deep, and we hear a lot of stuff about mining in the deep ocean — but the reality is, the biggest threat to the deep ocean we now know is overfishing."

As coastal waters are depleted around the world, the push to go deeper means shark and ray populations become "collateral damage" in fishery operations. 

Deepwater shark species, he said, have a "poorly understood but important role in regulating the ecosystems of the deep ocean."

The sharks are targeted for their liver oil, and today the substance ends up in a number of consumer products, he said. 

"Liver oil is kind of going under the radar," Dulvy said. "If you ask anybody about it, they'll never have heard about 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 about whether or not we can use liver oil because the product isn't labelled in any way," he said.