The organisation's Status of the Stocks report, which was published this week reveals that, in addition, 15 percent of the total tuna catch was from overfished stocks, and 1 percent was from stocks at an intermediate level of abundance.
Ratings for the following species have changed since ISSF’s last report in October:
- The spawning biomass (SSB) ratio for Atlantic Ocean yellowfin has improved from yellow to green.
- The fishing mortality rate ratio for Indian Ocean bigeye has downgraded from green to orange.
- The fishing mortality ratio for Indian Ocean albacore has downgraded from green to orange.
Those tuna stocks currently considered overfished and/or subject to overfishing include the Atlantic Ocean bigeye, Eastern Pacific yellowfin, Indian Ocean yellowfin, Pacific bluefin tuna stocks, Eastern Pacific bigeye, Indian Ocean bigeye and Indian Ocean albacore.
Meanwhile, all skipjack and most albacore stocks have been deemed “healthy”.
ISSF publishes its signature Status of the Stocks report twice each year using the most current scientific data on 23 major commercial tuna stocks.
- Abundance or “spawning biomass” levels: Globally, 65% of the 23 stocks are at healthy levels of abundance, 17.5% are overfished and 17.5% are at an intermediate level.
- Fishing mortality levels: 70% of the 23 stocks are experiencing a well-managed fishing mortality rate, and 30% are experiencing overfishing.
- Total catch: In 2018, the catch of major commercial tuna stocks was 5.1 million tonnes. 58% was skipjack tuna, followed by yellowfin (29%), bigeye (8%) and albacore (4%). Bluefin tunas accounted for 1% of the global catch.
- Largest tuna catches by stock: The five largest catches in tonnes, unchanged since the previous report, are Western Pacific Ocean skipjack, Western Pacific Ocean yellowfin, Indian Ocean skipjack, Indian Ocean yellowfin and Eastern Pacific Ocean skipjack.
- Tuna production by fishing gear: 66% of the catch is made by purse seining, followed by longline (10%), pole-and-line (8%), gillnets (4%) and miscellaneous gears (12%). These percentages changed minimally since the previous report.