POINTE A LA HACHE, La. -- The latest raft of bloated fish found in Plaquemines Parish probably died for the same reason as one found six days earlier -- low oxygen caused by high temperatures in shallow water, says Louisiana's top fisheries biologist.
Randy Pausina, assistant secretary for the Office of Fisheries in the Louisiana Department of Wildlife and Fisheries, said biologists went to check the fish kill at Bay Joe Wise on Friday, the day it was reported to his office.
He expected a report Monday, and expected it to show the same cause as a fish kill reported Sept. 10 in adjacent Bay Chaland.
"The hotter the water is, the less oxygen the water can hold," Pausina said. Heat also speeds up plant and animal metabolism, so they need more oxygen. Fish trapped in shallow water use up its oxygen and suffocate.
Pausina noted that both bays are connected to a web of canals dredged for oil and gas operations. The fish found Thursday may have died and sunk in those canals, then floated out to the bay during high tides after decomposition gases filled their bodies, he said.
Plaquemines Parish coastal zone director P.J. Hahn said Thursday that the fish covered at least one-fourth of a square mile, with oil visible among them. He said he wanted the area tested because it was affected by oil from the Gulf of Mexico spill.
The area is closed to fishing because of oil from the spill, but that doesn't mean oil killed the fish, Pausina said.
"Nobody's doubting there's oil in the marsh in those areas. That's why there's no harvest of fish in those areas," he said.
However, Pausina said, it can't be smelled and chemical analysis of water from every closed waterway in the state finds hydrocarbon levels below both advisory levels and the usual levels from normal seepage.
Oily water is far from new, noted University of New Orleans biology professor James M. Grady, whose interests include ecology of freshwater and marine fishes.
"Oil and oil sheen have been a part of our coastal waters since the state and local governments mortgaged the future of our coastal environments for the promises of oil riches," he wrote in an e-mail. "Clearly, no prior spill approximated the BP disaster, but seeing something oily in our marshes can mean many things."
The department checked regularly for BP oil on state waterbottoms throughout the summer and did not find any, said Olivia Watkins, a Department of Wildlife and Fisheries spokeswoman.
Hahn also said Plaquemines has never had fish kills this frequent and this extensive until this year.
That's nonsense, Pausina said.
Both kills in the Bay Chaland and Bay Joe Wise were predominantly menhaden, also called pogie.
"A pogie fish kill this size -- a menhaden fish kill -- it's small," he said.
It would be significant if even 20 fish died because of the Gulf of Mexico oil spill. But menhaden are extremely sensitive, and it's fairly common for 100,000 at a time to float up this time of year in south Louisiana's shallow waters, Pausina said.
(Copyright 2010 by The Associated Press. All Rights Reserved.)