Geneva, Switzerland-Bigeye tuna are under threat because authorities are failing to recognise the dire extent of overfishing.

In the Eastern Pacific up to 60 per cent of the bigeye tuna catch are small, juvenile fish, and the proportion of these is rising, says a new report from TRAFFIC, the wildlife monitoring network, and WWF.

"Removal of juvenile fish, before they reach adulthood and breed, compromises the sustainability of tuna stocks and reduces the availability of adults for the high-value sashimi markets in Japan," says Glenn Sant, TRAFFIC's Global Marine Programme Leader.

"Instead they end up being worth a few cents in a can, and tuna stocks are on the verge of collapse. The biological and economic future of the bigeye tuna fishery is at serious risk."

The report reveals that bigeye tuna stocks in the Eastern Pacific, Indian, Atlantic and Western and Central Pacific Oceans are all suffering from excessive fishing and the Eastern Pacific stock is overfished.

Bigeye tuna is highly prized in Japanese sashimi markets, but unless fisheries are better managed, the bigeye will become yet another endangered tuna species, like Atlantic and Southern bluefin tunas.

Measures needed include the setting of precautionary catch limits, introduction of bigeye population restoration programmes, halting the harvesting of juvenile fish, and improved data collection.