Tuna experts sceptical of Japanese bluefin tuna proposal

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Tuna experts are sceptical of Japanese government’s impending proposal to seek an increase in fishing quotas for Pacific bluefin.

The Japanese government is reportedly planning to put the proposal to Western and Central Pacific Fisheries Commission (WCPFC) at the Scientific Committee meeting in Busan, Korea later this month.

Their proposal will be made on the grounds that Pacific bluefin tuna stocks are on a recovery track.

However, Jamie Gibbon, the global tuna conservation officer with The Pew Charitable Trusts, says the Pacific bluefin tuna population is still severely depleted, at just 3.3 per cent of its unfished size.

He says overfishing was still occurring – with fishing rates more than twice the maximum sustainable level. Based on the current stock size, Gibbon says they opposed Japan’s proposal to increase catch limits for Pacific bluefin tuna.

“The projections that show future growth in the population are all heavily influenced by the estimate of recent recruitment (the number of new fish in the population in 2016) and that estimate is relatively uncertain, because it is based on just one observation from one source of data,” Gibbon says.

“Because of the depleted status of the population and the uncertainty about the accuracy of the future projections, we are urging members of the WCPFC to maintain the catch limits at the their current levels for at least the next two years, until a full stock assessment can be performed to confirm the results.”

Japan’s move, reports Japanese daily newspaper The Mainichi Shimbun, comes in response to a recent estimate by the International Scientific Committee (ISC) for Tuna and Tuna-like Species in the North Pacific Ocean that a provisional target for stock recovery can be achieved with a high probability, even if countries raised their tuna catch quotas.

After overfishing of bluefin tuna, which is a popular fish for sushi and sashimi, the WCPFC set a tentative target to recover stocks of bluefin tuna weighing 30 kilograms or more to 43,000 metric tons by 2024.

The Mainichi Shimbun reports that the ISC estimated that even if countries raised their tuna catch quotas by up to 15 per cent without differentiating between large tuna and small tuna weighing under 30kg, the probability of achieving the provisional target would be 74 per cent.

But Dr John Hampton, chief scientist and deputy director of the Pacific Community’s (SPC) Division of Fisheries, Aquaculture and Marine Ecosystems says he feels that the optimistic outlook was overly reliant on just one recent estimate of high recruitment, which was quite uncertain.

“If that estimate changes in the future, then the probability of meeting the recovery target would change,” Dr Hampton says. “In my opinion, it would be premature to increase quotas at this stage. I think we should wait until there is greater certainty regarding the recent high recruitment.”

Dr Hampton says the stock assessment report from the ISC also made the following cautionary statement: “However, it should be recognised that these projection results are strongly influenced by the inclusion of the relatively high, but uncertain recruitment estimate for 2016”.

The Pew Charitable Trusts’ Gibbon says the 16-year rebuilding plan for Pacific bluefin tuna was in just its first year, adding it was too early to start making changes.

“The members of WCFPC must give the plan time to work, or they threaten the future health of the Pacific bluefin population and the fisheries that depend on it.”