A Major Miscalculation

Fish play a major role in human survival. Globally, more than one billion poor people depend on fish as their main source of animal protein, and 250 million depend on  fishing and aquaculture for their livelihoods.

According to nonprofit research organization WorldFish, demand for fish is growing so much that the industry is struggling to meet it, and now, a new study published in Marine Policy suggests that we might have gotten some key numbers wrong in our past studies of global catch trends.

The authors of the study, Dirk Zeller from the University of Western Australia and Daniel Pauly from the University of British Columbia, believe that the poor quality of past recording and reporting methods may have caused researchers to overlook a significant portion of fish catches.

They argue that the seeming stability of fish catches is due to improved data collection in recent years. We now have a more accurate picture of the world's fishing industry, but because we didn't before, we didn't really know how catches were trending.

For their study, the researchers made estimated adjustments to past records. They collaborated with 400 assistants across the globe as part of their Sea Around Us project, gathering data from every fishing country.

Based on their adjustments to past data, we are catching a lot less fish than we were 20 years ago. “Our reconstructed data have shown that globally, the catches have been declining by about 1.2 million metric tons a year since the mid-1990s," Zeller told Oceans Deeply.

Fewer Fish or Less Fishing?

Some have criticized Zeller and Pauly for making too many assumptions about past data.

“We completely disagree with their conclusions of declining global catches,” Manuel Barange, the United Nations Food and Agriculture Organization's (FAO) fisheries and aquaculture director, told Oceans Deeply. “Total landings have been very consistent for 20 years."

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If the team's adjustments are accurate, though, they raise some important questions.

A decline in fish catches could simply mean that we are fishing less — perhaps diets are shifting in key areas of the world.

However, if the number of fishing boats at sea remained the same or even increased during the period of the study, as the authors suspect, the research could be a sign that the planet simply has fewer fish.

Past studies have noted the negative impact of pollution and climate change on fish populations, and if this study is evidence that global stocks have been declining for more than two decades, it adds new urgency to our need to address those problems.

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