Easing Off

January 17, 2016
By Damond Benningfield
Episode:

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Atlantic herring. Credit: National Oceanic and Atmospheric Administration

It may sound a bit obvious, but some recent research says that one way to stop a fishery from collapsing is to quit fishing there for a while. What’s not so obvious, though, is that doing so would have little impact on the overall catch.

The researchers looked at groups of forage fish — small fish like sardines, anchovies, and herring. These species are important to the fishing industry, but they’re also key links in the ocean food chain. They’re a major food source for larger fish, whales, birds, and other creatures.

The scientists looked at 55 fisheries around the world. The population had collapsed in about half of them, meaning that the number of fish had dropped to less than a quarter of average. They found that natural factors were responsible for the demise of about half of those groups. But the other half were helped along by fishing.

There were several common factors. The commercial harvest went up dramatically for several years before the collapse, for example. That contributed to a big drop in the number of young fish, so there were few new fish to replace the ones that were caught.

Researchers also simulated what might happen under various circumstances. They found that if fishing stopped when a fish population dropped below half of normal, then most collapses could be prevented. And the population would rebound more quickly, so the hiatus would shrink the catch by only about two percent. So in the long run, fishing fleets might catch more fish by catching less for a while.