Dead fish are washing ashore in Billings. But biologists say not to worry.

Posted at 3:26 PM, Mar 28, 2018
and last updated 2018-03-28 17:26:29-04

BILLINGS – State biologists are reporting noticeable dead fish in the water by Riverfront Park in south Billings, and they expect more in other areas as the winter ice melts.

Winter fish kills begin when plants at the bottom of ponds freeze, then get covered by the deep snow, according to Montana Fish, Wildlife, and Parks.

With the light covered by ice and snow, the plants die and are consumed by bacteria, which suck all the oxygen out of the water, the biologist said.

Fish floating on the surface now have died of anoxia, a reaction to the lack of oxygen in the water.

At Riverfront Park, biologists have discovered tiger muskies, big-mouth buffalo, river carpsuckers, white suckers, long-nose suckers, pumpkin seeds, carp, crappies, sunfish and a few bass. Scavenging animals will likely clear out most of the dead fish, and the remainder will sink to the bottom, according to Fish, Wildlife, and Parks.

There is a silver lining: fewer fish in the pond means less competition for food, which could mean bigger fish for anglers, according to Mike Ruggles, an FWP biologist. 

Lake Elmo in Billings Heights has traditionally been immune to this phenomenon because it has deeper spots and less vegetation on the bottom.