(NaturalNews) State wildlife officials are investigating a large fish kill at the mouth of the Mississippi River Gulf Outlet in St. Bernard Parish, Louisiana.
"By our estimates there were thousands, and I'm talking about 5,000 to 15,000 dead fish. Different species were found dead including crabs, sting rays, eel, drum, speckled trout, red fish, you name it, included in that kill," said parish president Craig Taffaro.
The fish were discovered on August 22, washed up on the shore as well as near a boom that had been set up to catch oil from the BP Deepwater Horizon oil spill. The next day, a thick, orange substance containing tar balls and giving off a "strong diesel smell" was found around nearby Grassy Island, according to a press release. Nevertheless, the oil spill might be unrelated to the recent fish kill.
"We don't want to jump to any conclusions because we've had some oxygen issues by the Bayou La Loutre Dam from time to time,'' Taffaro said. "It does point to the need for us to continue to monitor our waters and that's what we'll be doing."
The Department of Wildlife and Fisheries has issued a preliminary conclusion that the fish kill was caused by low oxygen levels in the water. According to head fisheries biologist Randy Pausina, extreme heat can cause oxygen levels in the water to plummet. When combined with already-low levels caused by nutrient-rich water flowing in from the Mississippi River, this can push levels below the threshold required to support aerobic life forms.
The Gulf of Mexico is home to the world's second-largest "dead zone," an area in which low oxygen levels have killed off all aquatic life. Scientists blame agricultural runoff -- consisting of nutrient-rich animal manure and fertilizer -- for causing the runaway growth of oxygen-consuming algae.
"No watershed projects or cleanup of the Gulf of Mexico 'dead zone' can hope to have long-term success unless synthetic nitrogen and phosphorus pollution is significantly reduced or eliminated," writes Will Allen in his book The War on Bugs.