Fish Discovered Surviving in Pacific Dead Zones

Researchers looking into the long term effects of the Pacific dead zones find some species weathering the storm

Grants Pass, OR—There’s good news, and there’s bad news. First let’s get the bad news out of the way; scientists think that the Pacific dead zones are still growing. These oxygen-depleted areas near the bottom of the ocean and large lakes can’t support life, and they’ve been concerning scientists and conservationists since the 70’s. But a new study, published last month in the journal Fisheries Oceanography, finds that some fish might be surviving even in these hostile conditions.

flickr/NOAA Photo Library
flickr/NOAA Photo Library

Dead zones have been a significant problem in the Pacific Northwest since the early 2000’s, and underwater cameras have been able to capture the impact on shallow water ecosystems. It’s also well known that tolerances for low oxygen levels differ among fish species, with trout and salmon being particularly sensitive. But until now there was little direct data on how species farther offshore were being affected.

“It’s rearranging the ocean geography,” said Jack Barth, an Oregon State University Oceanographer who participated in the study. Barth partnered with NOAA Fisheries Services researches. The team compared total catches for different species between 2008 and 2010. Oxygen measuring equipment attached to fishing nets allowed the researches to compare catches with oxygen levels. While some fisheries in the affected areas declined as expected, catches of Dover sole and greenstriped rockfish were unaffected. Dover sole are known to be adapted to low oxygen environments. The survival of greenstriped rockfish was a surprise, however. Barth expects that this data will lead commercial fisheries to change their emphasis, with more fishermen going after species less affected by dead zones.

“”If you go out to a spot where you’ve always gone before commercial fishing, and you don’t catch what you expect, is it because the oxygen has gone low and things moved someplace else?” said Barth.

As is often the case in science, the study raises more questions than it answers. Participating researcher Aimee Keller wants to know how other fisheries are affected by dead zones. She’s also interested in how dead zones could have broader affects on ecosystems—questions like whether growth rates or fertility will be affected, and whether species that can tolerate dead zones will gain a competitive edge. Such studies could take years though, and while they’re growing slowly, researchers have no doubt that dead zones are expanding.

Read more from the AP story at Oregon Live.

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