Dead zones in ocean threaten fish

January 22, 2011 by admin  
Filed under Protecting Habitats

FT. LAUDERDALE, Fla. — With the New Year comes new challenges to fish in our world’s oceans and one of the major concerns is the expansion of hypoxic zones. That’s the scientific name but more recreational anglers are becoming aware of them as “dead zones.”

They are areas in the oceans with low or non-existent oxygen levels which, according to a recently released research study by scientists and fish management experts, are increasing in size while decreasing the habitats of billfish and tuna. In scientific circles this phenomena is called “habitat compression.”

Ellen Peel, president of The Billfish Foundation (TBF) said scientists outfitted 79 sailfish and blue marlin in two strategic areas of the Atlantic with pop-off archival satellite tags which monitored their horizontal and vertical movement patterns.

“Billfish favor abundant habitats of oxygen-rich waters closer to the surface while avoiding waters low in oxygen,” Peel said. The study, composed of scientists from the National Oceanic and Atmospheric Administration (NOAA), the University of Miami Rosenstiel School of Marine and Atmospheric Science, and TBF, found a massive expanding low oxygen zone in the Atlantic Ocean is encroaching upon the fish forcing them into shallower waters where they are more likely to be caught. The research waters included areas off south Florida and the Caribbean (western North Atlantic); and off the coast of West Africa (the eastern tropical Atlantic).

Hypoxic zones occur naturally in areas of the world’s tropical and equatorial seas because of ongoing weather patterns, oceanographic and biological processes. In the current cycle of climate change and accelerated global warming, hypoxic areas are expanding and shoaling closer to the sea surface, and may continue to expand as sea temperatures rise.

“The zone off West Africa,” said Dr. Eric D. Prince, NOAA Fisheries Service research biologist, “encompasses virtually all the equatorial waters in the Atlantic Ocean, is roughly the size of the continental United States and is growing. With the current cycle of climate change and accelerated global warming we expect the size of this zone to increase, further reducing the available habitat for these fishes.”

Article source: http://www.delmarvanow.com/article/20110122/ESN03/101220329/-1/ESN

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