BALTIMORE COUNTY, Md. (WBFF) – About 6,000 fish were found to have died in eastern Baltimore County waterways, according to a Maryland Department of the Environment investigation.

Preliminary results point to algae-created toxins as the likely cause of the fish kill, which was discovered last week after dead fish were first seen in rivers that include the Gunpowder and Bird, said MDE spokesperson Jay Apperson Monday evening.

The kill has affected at least nine species: yellow perch, largemouth bass, bluegill sunfish, pumpkinseed sunfish, carp, black crappie, gizzard shad, spottail shiner and channel catfish.

Residents are urged to avoid the dead fish or wash their hands if they need to handle or dispose of the fish.

A department investigator who is on site today in response to the received reports “saw fish that continue to show signs of stress,” Apperson said.

The investigation has not shown any signs of pollution as a potential cause, suggesting instead that the kill is due to toxins produced by algae, he said.

“Monitoring has shown elevated cell counts of Karlodinium venifecum algae in the Gunpowder River,” Apperson said. “We are awaiting results of laboratory tests for algae toxins and of fish tissue. The investigation is ongoing.”

Apperson noted fish kills are relatively common and vary widely in size. MDE reports 86 fish kills in 2015, and it counts 55 fish kills of 100,000 or more fish since Maryland began investigating the issue in 1984.

Anyone with information on fish kills or with other concerns on environmental matters involving the Chesapeake Bay or its tributaries should call the Bay environmental hotline at 877-224-7229.