Fisheries Catch "Higher Than Reported and Declining"

In a study published Tuesday in Nature Communications, Professor Daniel Pauly and Dr. Dirk Zeller of the University of British Columbia Fisheries Center reported that global fish stocks have been declining more rapidly than previously known.

After ten years of work, their “catch reconstruction” data analysis project has produced detailed adjustments to the U.N. Food and Agriculture Organization (FAO)'s data set on global catch volume. The FAO data set is known to have trouble with underreporting (or no reporting) for the fisheries of many nations, and for a lack of data on subsectors like subsistence, artisanal and illegal fishing, and for discarded fish.

“The world is withdrawing from a joint bank account of fish without knowing what has been withdrawn or the remaining balance,” said Pauly. “Better estimating the amount we’re taking out can help ensure there is enough fish to sustain us in the future.”

Consistent with known underreporting, their reconstruction shows a much higher historical level of global fishery productivity, peaking at 130 million tons per year in 1996, and higher values than FAO numbers since.

Catch volume by sector, millions of tons (courtesy Sea Around Us)

But their data also show a more rapid decline from the peak than FAO's data, suggesting that fish stocks may be in danger of depletion from overfishing.

“This groundbreaking study confirms that we are taking far more fish from our oceans than the official data suggest,” said Joshua S. Reichert, executive vice president and head of environment initiatives for Pew Charitiable Trusts, a funder of the study.

When coupled with the effects of climate change, this trend could spell trouble. Professor Pauly was the coauthor of a previous UBC Fisheries Center study published in 2013, which found that warm-water species are already beginning to displace cold-water fish at higher latitudes. To the authors, this suggested that global warming is already affecting fish populations. It could also lead to a decline in fish stocks, especially in the tropics. "Further warming, to levels that exceed the temperature preference and tolerance of tropical species, is then expected to reduce their abundance," they concluded.

“We’ve been talking about climate change as if it’s something that’s going to happen in the distant future, [but] our study shows that it has been affecting our fisheries and oceans for decades,” Pauly said. “These global changes have implications for everyone in every part of the planet.”

Professor Pauly will feature in a new documentary film, “The Missing Fish,” for release in 2016.