A multinational organization that coordinates fishing activities in the western Pacific is throwing a lifeline to heavily overfished Pacific bluefin tuna stocks.

Speaking today at a press briefing, Japanese officials provided details on a plan agreed to last week that aims to rebuild the spawning population by halving the catch of juveniles and limiting takes of mature fish as well. The proposal calls for total Pacific bluefin catches to be kept below the 2002 to 2004 annual average levels and for catches of fish weighing fewer than 30 kilogramsâ€”juveniles too young to spawnâ€”to be reduced to 50% of those levels.

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Conservation organizations see the proposed limits as a step in the right direction. But they are "far from enough," Wakao Hanaoka, senior ocean campaigner for Greenpeace, tells ScienceInsider. He says that Pacific bluefin tuna stocks have shrunk to just 4% of the historical population, making proper stock management a matter of urgency.

A subcommittee of the Western and Central Pacific Fisheries Commission (WCPFC) agreed to the Japan-sponsored draft at a meeting last week in Fukuoka. The full commission will almost certainly adopt it at a meeting to be held in Samoa starting 1 December, explained Masanori Miyahara, an adviser to the ministry of agriculture who chaired last week's meeting. Reducing the take of juveniles that haven't yet spawned is one key to achieving the plan's initial goal of rebuilding spawning stock biomassâ€”the fish population able to reproduceâ€”to the historical median of 42,592 tons within 10 years. The biomass is now thought to be 26,000 tons, very near its all-time low. "Eating fish before they spawn is very wasteful," Miyahara says.

Bluefin tuna image via Shutterstock.

Read more at Science.