MAJORITY OF TUNA CATCH FROM HEALTHY STOCKS

Majority of tuna catch from healthy stocks – Of the total tuna catch, 86% came from stocks at “healthy” levels an unchanged share since last reported in October 2018, according to the March 2019 International Seafood Sustainability Foundation (ISSF) Status of the Stocks report.

Skipjack tuna stocks which remain at healthy levels in all ocean regions, still comprise over one-half of the total catch.

ISSF publishes its signature Status of the Stocks report at least twice each year using the most current scientific data on major commercial tuna stocks.

The fishing mortality rating was changed for two stocks since the previous report: The Fishing Mortality rating for both Mediterranean albacore and Western Pacific yellowfin was modified from “yellow” to “green.” The ISSF Scientific Advisory Committee (SAC) determined that this change was needed to harmonize those ratings and the report’s ratings methodology.

Though many of the recent broad indicators of overall global tuna stock health are positive, there are several stocks of concern that should be noted:

The Indian Ocean yellowfin stock has again been rated both as overfished and as suffering overfishing after a new stock assessment presented by the Indian Ocean Tuna Commission (IOTC) Scientific Committee in late 2018.

Similarly, the Pacific Ocean bluefin stock is also considered to be overfished, and overfishing of this stock continues.

Eastern Pacific bigeye is experiencing overfishing. Fishing mortality for this species is high.

Two consecutive assessments have concluded that Atlantic Ocean bigeye is overfished and that overfishing is still occurring.

Key statistics in the report

Total catch: In 2017, as reported in the new report, the total major commercial tuna catch was 4.8 million tonnes. More than half of the total catch (58%) was skipjack tuna, followed by yellowfin (28%), bigeye (8%) and albacore (5%). Bluefin tunas (3 species) accounted for only 1% of the global catch. These percentages changed only slightly from the October 2018 Status of the Stocks report.
Abundance or “spawning biomass” levels: Globally, 65% of the 23 stocks are at a healthy level of abundance, 13% are overfished and 22% are at an intermediate level. In terms of total catch, 86% come from healthy stocks, 10% from overfished stocks and 4% from stocks at an intermediate level. Unchanged from the last report, the stocks receiving orange scores — indicating overfished status — were Atlantic Ocean bigeye, Pacific Ocean bluefin and Indian Ocean yellowfin.

Fishing mortality levels: 78% of the 23 stocks are experiencing a well-managed fishing mortality rate, 18% are experiencing overfishing, and 4% have a high fishing mortality rate.

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 ocean region: More than half (52%) 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 (11%). Catch from Pacific-wide stocks accounts for around 3% of the global catch, while catch in the Southern Hemisphere accounts for less than 1%.

Tuna production by fishing gear: 65% of the catch is made by purse seining, followed by longline (11%), pole-and-line (8%), gillnets (4%) and miscellaneous gears (12%).

These percentages have changed only slightly since the October report.