Quotas for Pacific bluefin tuna

Countries that fish for Pacific bluefin tuna have agreed on a new quota rule that paves the way for bigger catches if conditions affecting the species’ population improve. The rule, which incorporates a proposal put forth by Japan, includes a specific short-term goal of increasing the population. But the target itself is low. As a major consumer of bluefin tuna, Japan should be aware that the danger of resource depletion remains. It should make convincing efforts to help restore the population.

Most Pacific bluefin tuna are caught in the Northern Pacific. High-grade fatty flesh of tuna, or toro, is popular for sushi and sashimi. Japan harvests more than half the total catch, although bluefin accounted for only about 10 percent of the tuna sold in the Japanese market in 2015.

In 1961, the total stock of mature Pacific bluefin tuna, which can spawn, stood at 160,000 tons. The stock dwindled to a mere 16,500 tons in 2014 — roughly one-tenth the 1961 level and only 2.6 percent of the species’ historic population — a hypothetical size assumed to have existed before large-scale fishing activities began.

The Western and Central Pacific Fisheries Commission (WCPFC) aims to increase the stock of mature bluefin tuna to 41,000 tons by 2024 by halving the catch of immature tuna — weighing less than 30 kg — from the average catch in the base years of 2002-2004, which saw relatively good harvests. At a five-day meeting of the WCPFC’s Northern Committee in the South Korean city of Busan that ended Sept. 1, Japan, the United States, South Korea and seven other countries agreed to introduce a new rule, under which catch quotas would be reduced if resource surveys show that the probability of achieving the target of stock restoration is 60 percent or lower, while on the other hand the countries could consider expanding their quotas if the probability of achieving the target tops 75 percent. The new rule is expected to be approved by the WCPFC at its meeting in December.

The new rule reflects Japan’s proposal that there should be a clear sign that catch quotas can be expanded if there is a probability the stock will be restored — which Tokyo hopes will encourage Japanese fishermen to take positive steps to preserve the species and restore its numbers to a sustainable level. Behind the proposal were complaints by fishermen about tuna fishing regulations. But the committee turned down the Japanese proposal that called for considering higher catch quotas if the probability of accomplishing the restoration target exceeds 65 percent, opting for the 75 percent threshold instead.

However, the problem with the new rule is that the target of restoring the stock to 41,000 tons in itself is still low. A near-automatic increase in catch quotas when probability rises for achieving such a target underestimates the risk of species depletion. Resource surveys involve various uncertainties, and the estimated probability of accomplishing the target based on those surveys can be similarly uncertain. There is also a risk of unexpected developments affecting the size of the stock. One cannot be too cautious about increasing catch quotas under these conditions.

At the Busan meeting, the committee also introduced a new long-term target of increasing the stock of mature bluefin tuna to 130,000 tons by 2034 or 20 percent of its historic population, which represents a nearly eightfold increase from 2014 levels. Initially reluctant about setting such a long-term target, Japan reversed its position to accept the goal in the face of strong international criticism of its behavior, including rampant illegal and unreported fishing that ignored Fisheries Agency regulations. As the biggest catcher and consumer of Pacific bluefin tuna, Japan bears a grave responsibility for making serious efforts to help restore the stock. Such efforts will require strict and sustained long-term management of it. The government needs to establish a durable strategy to achieve the long-term target.

Behind the steep decline in the stock are the appetite of consumers to eat tuna in large volumes at affordable prices and moves by fishermen to catch immature — and inexpensive — tuna in response to such demand. Both consumers and fishermen need to realize that bluefin tuna is not a species fit for such mass consumption. They need to take the current conditions of the bluefin tuna stock seriously and act responsibly by contributing to the efforts to help rebuild the population.