The Current

Conservationists fear surplus of Atlantic bluefin tuna does not equate to healthy stock

As with any great fishing story, there's a dispute over facts.
As with any great fishing story, there's a dispute over facts. (Submitted by Brian Skerry )

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Fishermen say Atlantic bluefin tuna are showing up in unprecedented numbers off the coast of PEI. But while federal government scientist says the species is on the rebound, conservationists are skeptical.

The stock declined 70 per cent from the 1960s to the early 2000s, with Canadian scientists warning the species was endangered in 2011.

Recently, the tuna has been making international waves. (CBC)
With no protection under the Species At Risk Act, Atlantic bluefin tuna is always under pressure from fish buyers who supply sushi restaurants, and sport fishermen who seek the thrill of landing a fish that can weigh as much as a grand piano.

"There's no animal like it, but because they're a fish, we don't give them their due," says Brian Skerry, a photographer whose work appears in National Geographic.

Skerry says that tuna can move faster than a torpedo and have been studied by naval engineers to make better torpedos. They are also endothermic making them able to travel from the equator to the poles.

It's a predator that swims thousands, tens of thousands of miles in the course of a year — they crisscross the entire ocean. There's no predator on land that travels those distances.- Brian Skerry  on tuna

Bluefin tuna on the western Atlantic spawn in the Gulf of Mexico, and then come as far north as the south coast of Newfoundland to feed. Because of the mass migrations, the tuna populations are hard to monitor.

According to filmmaker John Hopkins, who created the the award-winning National Film Board documentary Bluefin about the abundance of bluefin tuna in North Lake, P.E.I., the fish are literally eating out of people's hands.

The fish are finding us, we aren't finding them.- John Hopkins on starving tuna

Hopkins tells The Current's guest host Piya Chattopadhyay that the tuna are hunting down boats as a food source because these fish are "starving" when they come up from the Gulf of Mexico.

Scientist Gary Melvin, with the Department of Fisheries and Oceans, doesn't agree.

"We have no evidence that there's actually sort of food problems," says Melvin, who is also the chair of Western Bluefin Tuna Stock Assessment Working Group.

"We see fat fish. We see the relationship between the size of the fish and the weight of the fish remaining relatively constant. So from that perspective we have no evidence to suggest that their food is limiting." 

'These tuna are far too vulnerable."- John Hopkins

But Hopkins contends the DFO was not using sound scientific methods to assess the health and the size of tuna stocks. 
"Bluefin are not behaving normally anymore. This intense situation is fouling the math DFO uses to assess the stock,"

Hopkins wrote in a letter to The Current after the interview with Melvin. "These tuna are far too vulnerable and the data from this is throwing up false assumptions."

Katie Schleit, who leads work on tuna conservation at the Ecology Action Centre in Halifax, agrees with Hopkins. In a followup interview after this segment aired, Schleit pointed out that the International Commission for the Conservation of Atlantic Tuna, or ICCAT, sees this as a problem too.

"Because there have been more tuna in the Gulf of St. Lawrence, when the fishermen go out to catch them, they're having a 100 per cent catchability," she said.

"But this isn't actually reflective of a natural biological population. And that information is reflected in the ICCAT science assessment." 

Schleit said if the population spike in the Gulf of St. Lawrence were removed from global data, then the world's tuna stocks would not appear to be rising nearly as fast. 

Listen to the full conversation at the top of this post. 

The segment was produced by Halifax network producer Alex Mason.