An international conference on sustainable management of Pacific bluefin tuna has agreed to increase catch quotas for larger fish, meeting a key demand from Japan.

The agreement was reached August 18 in closed-door online talks, according to Japanese government sources. The meeting was an unusual resumption of negotiations held in July that ended without a deal after Mexico opposed the proposed changes.

According to Kyodo News, the new agreement could allow quotas to increase partially from 2027, potentially making Pacific bluefin tuna more widely available to consumers.

Japan had sought to raise the quota for larger fish by about 25% from current levels while reducing the quota for smaller fish by about 6%. Smaller fish are considered important to securing future stocks.

Pacific bluefin tuna is widely used in high-end sushi and other dishes. Its population fell sharply because of overfishing but has recovered in recent years under strict international management rules.

At a weeklong meeting in Nagasaki that ended July 14, negotiators had made progress towards a new management system under which catch quotas would be set automatically according to stock levels. The system was similar to a proposal put forward by Japan.

Mexico objected shortly before an agreement was due to be reached. Sources involved in the negotiations said Mexico was concerned that countries in the Western and Central Pacific, including Japan, could catch more tuna than anticipated.

Japan subsequently persuaded Mexico to change its position, allowing the talks to reach an agreement backed by Japan and other countries and regions.

Under the new quota for the Western and Central Pacific region, the catch limit for larger fish will rise from 11,869 tonnes to 14,836 tonnes. The limit for smaller fish will fall from 5,125 tonnes to 4,823 tonnes.

The allocation of the larger and smaller fish quotas among individual countries and regions will be negotiated later. Japan plans to discuss its allocation with South Korea and Taiwan.

Japanese farm minister Norikazu Suzuki welcomed the agreement at a press conference after the talks, while noting that further negotiations remained.

Takumi Fukuda, a senior official at Japan’s Fisheries Agency who represented the Japanese government at the talks, said Japan would remain vigilant as negotiations continued.

Pacific bluefin tuna is managed in the Western and Central Pacific by the Western and Central Pacific Fisheries Commission. The species is managed in the eastern Pacific by the Inter-American Tropical Tuna Commission.

The agreement is expected to be approved at the annual meetings of both organisations later this year. It is scheduled to take effect from 2027.