DENISON – Texas Parks and Wildlife Department fisheries biologists have concluded an investigation into a fish kill that occurred June 21 to 24 in the Paradise Cove area of the Big Mineral arm at Lake Texoma.

Biologists estimated the fish kill resulted in approximately 157,000 dead fish in the area, of which more than 90 percent were small (1 inch) threadfin shad. Other fish species significantly affected included an estimated 9,122 freshwater drum and 1,332 crappie.

Water samples taken by biologists confirmed the presence of golden alga and elevated toxin levels in the lake. Although not harmful to humans or other animals, these alga produce an ichthyotoxin, or fish toxin, which adversely affects gill-breathing organisms such as fish, bivalves, crayfish, gilled amphibians, and also some species of plankton. The toxin damages the permeability of gill cells, and causes the gills to lose their ability to exchange water and absorb oxygen from the surrounding water.

Smallmouth buffalo, channel catfish, white bass, and goldeye were also identified in the kill; although, the estimated number included less than 100 individuals of each species. No striped bass were believed to have been affected by the fish kill event, and just one largemouth bass was observed.

The recent fish kill comes as a bit of bad news to an otherwise string of positive news coming from Lake Texoma, said Dan Bennett, TPWD inland fisheries district biologist. In particular, he noted the striped and white bass populations are currently at above-average levels and are exhibiting fast growth in the lake.

“Fish populations have really rebounded in the reservoir following the flooding in 2015,” Bennett said. “We have observed tremendous spawning events in the last three years, producing above average classes of young fish of all species. We hope this fish kill event remains an isolated occurrence and doesn’t pose additional risk to other areas of Lake Texoma.”

First identified in Texas in 1985, golden alga has since been responsible for fish kills in Lake Texoma in the Red River Basin as well as other reservoirs in the Colorado, Canadian, Wichita, Brazos, Rio Grande and San Jacinto river systems. Bennett said no practical solution has been found for effectively treating golden alga in large reservoirs.

More information on golden alga and its impacts on Texas water bodies can be found at http://tpwd.texas.gov/landwater/water/environconcerns/hab/ga/.