Investigators hopeful death rate slowing down
Megan Miller
Cumberland Times-News
— DEEP CREEK LAKE — The death toll of the June fish kill in Deep Creek Lake has reached approximately 1,000 and counting, but environmental investigators are hopeful the rate of fish deaths is slowing.
Investigators are attributing the fish kill to unprecedented high water temperatures in the lake, combined with the speed at which the water temperature rose. The water heated up too quickly for the fish to become acclimated.
“The vast majority of fish kills are really natural, as this one apparently is as well,” said Maryland Department of the Environment Program Manager Charlie Poukish, who investigated the incident. “Our main interest, of course, is to get out quick enough to try to document if there is some sort of toxin — the old canary in the coal mine.”
But instead of a toxin, Poukish said the Deep Creek Lake fish appear to be victims of a combination of stresses. Those stresses, including the higher water temperature, made them more susceptible to parasites.
“We noticed a very heavy parasite load on the fish,” Poukish said, adding, “The ultimate cause of death was really septicemia, which was brought on by a common bacteria found in nature which really doesn’t affect fish until they’re stressed.”
Long term monitoring by the Department of Natural Resources showed that the lake’s surface water temperature in July was the hottest it’s been through the entire data collection period — the years 2000, 2002 to 2003, and 2008 to 2010.
Temperatures in the upper layer of lake water were between 76 and 80 degrees. Many of the dead fish were cold water species, such as yellow perch, walleye, smallmouth bass and northern pike, that thrive in temperatures less than 73.4 degrees.
Insufficient oxygen levels in deeper layers of the lake might have prevented the fish from escaping to cooler water below, Poukish said.
The first dead fish began appearing on or around July 17. Escalating numbers of dead fish prompted an investigation by local environmental agencies, MDE and the Department of Natural Resources.
Testing is ongoing to determine the specific type of protozoan parasite found on the fish, Poukish said.
There appears to be no threat to human health, and the fish parasite cannot infect people, according to MDE officials. But touching, eating, swimming with, or coming into close proximity to any dead fish should still be avoided.
Fish kills and algae blooms may be reported by calling 1-866-MDE-GOTO or 877-224-RBAY.
