Fish under threat in ocean 'dead zones'

MIAMI, Dec. 14 (UPI) -- Ocean "dead zones" are threatening blue marlin, billfish and tropical tuna, all active fish that need large amounts of dissolved oxygen, U.S. researchers say.

Scientist at the University of Miami say the expansion of dead zones -- areas of low oxygen driven in part by climate change -- is shrinking the usable habitat for these highly valuable pelagic fish in the tropical northeast Atlantic Ocean.

The dead zones, depriving fish of areas with enough dissolved oxygen for them to thrive, are forcing these species into surface waters where they are more vulnerable to fishing, a release by the university's Rosenstiel School of Marine & Atmospheric Science said Wednesday.

"In human terms, you might describe it as if you were in a house on fire with all of the doors and windows were locked, leaving only one exit, then discovering you have a robber inside the house at the same time," said UM researcher Jiangang Luo.

"Working closely with oceanographers, we are getting a much clearer picture of how climate-driven dead zones are shrinking the habitat for some of the world's most valuable fish," he said.