The latest International Seafood Sustainability Foundation (ISSF) Status of the Stocks report revealed that skipjack tuna stocks — at healthy levels in all ocean regions — constituted more than half of the 2016 total catch.
While the overall proportion of the catch coming from healthy stocks remains unchanged, Southern bluefin tuna has moved from orange to yellow in abundance ratings. Stock abundance is low, about 13 percent of the unfished level. However, the stock is rebuilding continuously as a result of the implementation of a robust management procedure (a harvest strategy) by the Commission for the Conservation of Southern bluefin Tuna, the regional organisation in charge of managing the stock. In contrast, the Pacific bluefin stock, along with the Indian Ocean yellowfin stock and the Atlantic Ocean bigeye stock remain overfished.
There were no dramatic changes in tuna stock status since the previous November 2017 Status report; the updated report reflects new data made available at late 2017 tuna Regional Fisheries Management Organization (RFMO) meetings.
Updated several times per year, Status of the Stocks assigns color ratings (green, yellow or orange) on stock heath, stock management, and ecosystem impact. The report ranks the 23 stocks of major commercial tunas around the world using a consistent methodology.
- Total catch: In 2016, the total major commercial tuna catch was 4.9 million tonnes, a 2% increase from 2015. More than half of the total catch (57%) was skipjack tuna, followed by yellowfin (30%), bigeye (8%) and albacore (4%). Bluefin tunas (3 species) accounted for only 1% of the global catch. These percentages changed only slightly from the Nov. 2017 reporting period.
- Abundance or “spawning biomass” levels: Globally, 57% of the 23 stocks are at a healthy level of abundance, 13% are overfished, and 30% are at an intermediate level.
- Stocks receiving orange scores, indicating overfished status, include Atlantic Ocean bigeye, Pacific Ocean bluefin and Indian Ocean yellowfin.
- Fishing mortality levels: 65% of the 23 stocks are experiencing a well-managed fishing mortality rate, and 13% are experiencing overfishing (with no change from the previous report).
- Largest catches by stock: The three largest catches in tonnes are Western Pacific Ocean skipjack, Western Pacific Ocean yellowfin, and Indian Ocean skipjack.
- Tuna production by ocean region: Most (53%) of the world’s tuna is harvested from the Western and Central Pacific Ocean, followed by the Indian Ocean (20%), Eastern Pacific Ocean (13%), and Atlantic Ocean (10%).
- Tuna production by fishing gear: 65% of the catch is made by purse seining, followed by longline (12%), pole-and-line (8%), gillnets (3%) and miscellaneous gears (12%). These percentages changed only slightly from the November 2017 reporting period.