Unusual Freeze Frame: Frozen Fish Kill

Titled “Fishicicles” by Kelly Preheim. Common carp, mostly, frozen in ice at Lake Andes National Wildlife Refuge in South Dakota.

Back in 2015, Kelly Preheim, a regular visitor to Lake Andes National Wildlife Refuge witnessed a startling sight.

Explanation of the Frozen Fish Kill

Kelly explains the reasoning behind the startling sight of many frozen common carp and a few other fish species. The lake levels were low due to drought. The fish kill was due to depleted oxygen. When thick ice (particularly if it gets covered with snow) forms on a lake’s surface, it blocks out the sun, and the algae/plants don’t photosynthesize and produce oxygen, thus depleting oxygen levels. If the aquatic plants and algae subsequently die and decompose, this also uses oxygen, further depleting levels, so the fish essentially suffocate from lack of oxygen.

Bald eagles made the most of the fish kill. Photo by Kelly Preheim.

The fish died and floated to the surface. When the weather turned even colder, the ice expanded pushing it toward the shore where it buckled and went vertical. or it may have been driven there by very strong winds. The thousands of frozen fish on the lake attracted hundreds of bald eagles, various gulls and American crows as they fed on the dead fish. It was quite a sight and it smelled very fishy out there for quite awhile.”

Photo by Kelly Preheim.

About the Refuge

Lake Andes National Wildlife Refuge is a natural, shallow prairie lake in south-central South Dakota. The refuge’s lands and waters are important to migratory birds along the Central Flyway. Lake Andes is one of 566 national wildlife refuges in the United States.

About Kelly Preheim

She’s an avid birder and keeps a birding blog of her birding adventures and work with young students dealing with birds. Follow her on Flickr or visit her blog.