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Ocean Oxygen 'Dead Zones' Causing Drop In Fish Numbers, Diversity Off West Coast

GRANTS PASS (CBS/AP) -- Concerned that low-oxygen dead zones in the Pacific off the West Coast are getting more common as the climate changes, scientists are looking at how commercially valuable fish are reacting.

A study published in the journal Fisheries Oceanography found overall numbers and diversity of fish declined as oxygen levels dropped in deep waters, but some fish remained, able to ride it out.

Lead author Aimee Keller, a fisheries biologist for the Northwest Fisheries Science Center, says dead zones have been expanding since 2002, and scientists wanted to know how fish are reacting. So they put oxygen sensors on the nets of fishing trawlers doing annual surveys of groundfish populations.

She says the surveys also found that about 60 percent of the places the trawlers went had low oxygen.

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