The International Seafood Sustainability Foundation (ISSF) has released the latest version of its Status of the Stocks today. The report compiles the scientific records of the different major tuna stocks done by each of the Regional Fisheries Management Organisations (RFMOs) into one document, serving as a one-stop resource for comprehensive tuna stock information. The Status of the Stocks Report uses a colour rating system to indicate varying degrees of stock heath and ecosystem impact.
The most noticeable update since the last version released in November 2015 is that Indian Ocean yellowfin stock assessment indicates a decline in status. Overall, catches of Indian Ocean yellowfin have declined by 19% from a record high of 530,000 tonnes in 2004, but seem to be increasing again, especially in purse seine and other fisheries.
The stock is estimated to be overfished and overfishing is occurring due to an increase in catch levels in recent years.
There are 23 stocks of the major commercial tuna species worldwide – six albacore, four bigeye, four bluefin, five skipjack and four yellowfin stocks. The Status of the Stocks summarises the results of the most recent scientific assessments of these stocks, as well as the current management measures adopted by the RFMOs. In addition, this report ranks the status and management of the 23 stocks using a consistent methodology in terms of three factors: Abundance, Exploitation/Management (fishing mortality) and Environmental Impact (bycatch).
In 2014, the catch of major commercial tunas was 5 million tonnes, a 4% increase from 2013. Fifty-seven percent of it was skipjack tuna, followed by yellowfin (27%), bigeye (9%) and albacore (6%). The four stocks of bluefin tuna account for only 1% of the global catch.
Globally, 48% of the stocks are at a healthy level of abundance, 39% are overfished and 13% are at an intermediate level. In terms of exploitation, 48% of the stocks are experiencing a low fishing mortality rate and 17% need stronger management to end overfishing.
When viewed from the point of view of total catch, 78% of the catch comes from healthy stocks. This is due to the fact that skipjack stocks are healthy and account for more than half of the global catch of tunas.
In contrast, most bluefin stocks and two out of six albacore stocks are thought to be overfished, but combined they make-up a relatively small fraction of the total catch. In terms of fishing mortality, 13% of the total tuna catch comes from stocks where fishing is not well managed.