Pacific Tuna’s survival still confronted by formidable problems

The Guardian reports, 22nd January 2016: In Japan, 347 of Iki’s family fishermen [Iki, an island in the Sea of Japan] formed an organisation in 2014 to lobby for stricter rules on the Pacific tuna fishery, and last year they took the economically punishing step of halting their own harvest of adult tuna during the spawning season.

However the purse seiners did not follow suit.

Nor has Japan’s government imposed an official ban on the practice. Fisheries ministry officials argue that over-fishing of juveniles, not spawning adults, is responsible for the species’ decline, and cite data from international management bodies to back up their claim.

But some fisheries scientists say that the targeting of spawning bluefin is also threatening the future of the species.

Decades of over-fishing have already reduced the once-abundant Pacific bluefin to around four percent of its historic levels, according to the latest stock assessment by the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean, which is charged with studying them.

That is an even more dramatic decline than Atlantic tuna have suffered. In the past few years, the number of young fish that survive to join the population has also been low. Those findings prompted the International Union for Conservation of Nature (IUCN) to declare Pacific bluefin vulnerable — one step below being endangered — in late 2014.

“All the analyses indicates that the stock is doing very poorly,” says Maria José Juan Jordá, a fisheries scientist who contributed to the IUCN assessment. Scientists don’t know exactly how close the species is to collapse, she says, but virtually all models show current fishing levels are unsustainable.

International concern is currently focused more on over-fishing of juveniles than on spawning adults. These young fish weigh less than 65 pounds — compared to the adult record of 907 pounds — and are targeted in part to supply the aquaculture industry, which fattens up juveniles in sea pens.

“At the moment the vast majority of Pacific bluefin are being caught in Japanese waters before reproductive age, and it’s effectively mining out the reproductive capacity of that population,” says Amanda Nickson, director of global tuna conservation at the Pew Charitable Trusts.

According to a study commissioned by her organisation, halting the harvest of juveniles throughout the Pacific Ocean could quadruple stocks in as little as five years.

Source: The Guardian, 22nd January 2016. For the full story, see

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