Investigators with the Maryland Department of the Environment blamed the largest fish kill in the state this year on a lethal type of algae toxin, the agency said Tuesday.
Up to 200,000 fish were killed in the Upper Middle River and its tributaries last month, the investigation found. Officials said they found no evidence that the fish kill was caused by chemicals.
MDE blamed the fish kill on a type of algae called Karlodinium veneficum, which damages the gills of fish so that they can't take in oxygen. The algae may have bloomed in the warmer waters this fall, then died off when the temperature dropped, releasing the fatal toxin.
The fish killed included largemouth bass, yellow perch, bluegills, crappies, chain pickerel, pumpkinseed sunfish, carp, killifish, Atlantic menhaden, spottail shiner and gizzard shad.