Are fish harvest estimates even close to being accurate? Maybe not.

It has long been known that not only are humans taking too many fish from the sea, but also much of what is taken isn’t even reported. Now, for the first time, researchers from the University of British Columbia have calculated by just how much official statistics underestimate the global harvest—and it isn’t pretty.

In an ambitious paper spanning the globe, researchers concluded that since 1950, reconstructed catches are overall 53 percent higher than the reported data. Researchers also found that since the peak in fishing in 1996, total landings have declined three times faster than official statistics would have us believe.

While at first blush that decline might sound like good news—and indeed, some critics of the study insist it is—the authors conclude that the decline in landings is due to the sad fact that fish stocks are declining, too.

The Food and Agriculture Organization of the United Nations collects fishing data from member countries and produces the world’s official statistics on how many fish are caught from our oceans each year. But member nations often significantly underestimate the landings of small-scale and subsistence fishers. Meanwhile, recreational catch, discarded bycatch, and illegal fishing are often not even counted at all.

That’s why UBC professors Daniel Pauly and Dirk Zeller undertook a so-called “catch reconstruction” to calculate a more inclusive global statistic. They reviewed the scientific literature, official government statistics, and industry statistics and connected with hundreds of colleagues and local experts in 200 countries around the globe.

They estimated that, at the peak of fishing in 1996, there were really 130 million tonnes (mt) of fish landed—not 86 mt—and that the amount has declined by 1.22 mt per year—not 0.38 mt. In 2010, the last year analyzed in the study, they found that 109 mt of fish were landed—not 77 mt—a roughly 30 percent difference.

Contrast between the world’s marine fisheries catches, assembled by FAO from voluntary submissions of its member countries (‘reported’) and that of the catch ‘reconstructed’ to include all fisheries known to exist, in all countries and in the High Sea (‘reconstructed’=‘reported’+estimates of ‘unreported’). From Pauly, D. & Zeller, D. 2016.

Contrast between the world’s marine fisheries catches, assembled by FAO from voluntary submissions of its member countries (‘reported’) and that of the catch ‘reconstructed’ to include all fisheries known to exist, in all countries and in the High Sea (‘reconstructed’=‘reported’+estimates of ‘unreported’). From Pauly, D. & Zeller, D. 2016.

Heralded as a landmark paper by some, the study goes too far, critics say,  by using the amount of fish taken from the ocean as a reliable indicator of the abundance of fish. The Marine Stewardship Council, a private fishing standards and certification group, along with other fisheries researchers, says the decline in landings may well reflect better-managed fisheries and the implementation of quotas to enable fish stocks to rebound.

Pauly disagrees. “We have checked that essentially the same declines occur after we delete all countries that use quotas for management, in North America, the EU, Australia, etc.” Be that as it may, Pauly does see a silver lining. He says that the higher landings calculated in the paper mean that the world’s oceans are actually more productive than anyone ever believed, adding, “They are even more worth fixing than we thought.”

Source: Pauly D and Zeller D. Catch reconstructions reveal that global marine fisheries catches are higher than reported and decliningNature Communications. 2016.
Header image: Shutterstock.com

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