Tuna to Tango

Catch quotas threaten bluefin tuna despite scientists’ recommendations. By Susan Cosier

Credit: © WWF-Canon / Michel GUNTHER 

In the dark waters of the Atlantic Ocean, fleets of fishermen scour the sea in search of the increasingly rare bluefin tuna. Demand for tuna and the high price it commands has led to a steep decline in the population, and stocks will likely collapse entirely unless governing bodies adopt and enforce stricter regulations, experts say.

In January, members of the International Commission for the Conservation of Atlantic Tunas (ICCAT), the body that determines the amount of tuna fishermen can take from that ocean, decided on a management plan that conflicts with scientists’ recommendations. As it stands now, this year’s allowable quota is higher than last year’s—despite the increasing body of knowledge about the fish and its imminent decline.

“Even the perfect implementation of this management plan will lead to the collapse in the short term,” says Sergi Tudela, head of the Fisheries Program at the World Wildlife Fund’s Mediterranean program office. “We are extremely concerned.”

Since 1970, tuna stocks have plunged 90 percent, says Barbara Block, a fish biologist at Stanford University. Bluefin tuna can weigh up to 1,500 pounds and take as many as 30 years to mature, so when fishermen hunt older fish, it takes a long time for their numbers to rebound. In order to allow the population to recover, this year ICCAT’s scientific committee recommended that countries that fish for tuna in the Atlantic limit their catches to 15,000 tons. Instead, the quota now stands at 32,500 tons, explains Tudela. The actual amount is estimated at about 50,000 tons caught annually when illegal, unregulated, and unreported catches are included.

Credit: © Monterey Bay Aquarium Foundation / Randy WILDER 

Managing tuna stocks has never been easy, but a recent scientific discovery has made it even more challenging. In January scientists confirmed the existence of two distinct populations of tuna in the Atlantic: eastern and western. Since the two species swim in the same waters until they spawn, fisherman have trouble distinguishing between the two, so setting limits on each individual population is difficult.

Researchers identified the two tuna species with genetic testing and an innovative approach called biologging, a technique that involves tagging and tracking the fish across the oceans. These tags, which cost about as much as a laptop, allow scientists to collect far more information than older models did. The devices measure water temperature, the tuna’s body temperature, depth, and light, which can help them locate the fish, explains Block. Over the course of the tag’s five-year lifecycle, scientists can collect these data to determine where the tuna travels, feeds, and breeds. So far, Block and her colleagues have attached about 1,000 tags.

“We’re able now to see below the sea,” says Block, a founder of the Tag-A-Giant Foundation, a Stanford University bluefin tuna conservation program. “We’ve punched through a barrier in the last decade in terms of technology,” she says.

Policy makers might not yet be listening to scientists’ recommendations, but researchers persist in gathering data on the stocks. As populations continue to decline and demand for the tasty fish remains steady, some say farmed tuna could become a viable alternative. Already Japan has had some success with farming, says Block.

Meanwhile, groups like the WWF are asking consumers and nations buying the fish to make responsible decisions (i.e. not buying Atlantic bluefin tuna unless countries voluntarily decide to reduce their catch quotas). The WWF is also requesting that ICCAT convene an emergency meeting to revise its management plan. Whether the group meets or not, the WWF will continue to fight to preserve the bluefin tuna.

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As a Pisces, and a tuna lover, thank you for the insightful article - well written, informative, terrific! Thank you, Ms. Cosier!!!

And if we didn't have enough of a reason to avoid tuna consumption, the writer didn't even mention mercury, which tends to accumulate in large predatory fish. Plant-based sources of protein are usually much for more sustainable and contain less toxins.

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