Conditions after Hurricane Ida killed about 280 million fish in inland waters — about 40% more than died after Hurricane Andrew in 1992, the Louisiana Department of Wildlife and Fisheries estimated Thursday.
It said 19 of 20 big fish kills were in areas where hurricane-force winds roared through.
Catchable fish are usually scarce for about a year in areas which had big fish kills, but populations rebound, the department said in a news release.
The kills are caused by low oxygen levels after tropical storm winds and storm surge churn up sediment and dump in debris, which uses oxygen as it decomposes.
This year, most of the fish died within a week of Ida’s Aug. 29 landfall, in an area covering about 2,800 square miles, the department said.
There’s no way to get an exact number of fish killed, the department emphasized. It said the estimate was based on factors including wetland maps, the known extent of fish kills, historic sampling, and expert opinion about kills’ severity.
Wildlife and Fisheries logged information from staff observation, public phone calls and social media posts about 20 fish kills throughout southeast Louisiana.
One near Gibson was the only one where winds were less than 74 miles per hour, the department said.
It said Lake Maurepas drainages were particularly hard hit, but fish in Lake Pontchartrain and the east bank of New Orleans seem to have been largely spared.
In the months after a fish kill, surviving fish spread out into areas where they now have little predation or competition for increased nutrients. “The following spring, they will spawn with extremely high success rates,” the department said.
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