Devils Lake Freshwater Shrimp

As a child growing up in northwestern North Dakota, seafood was a special treat, to the point that even fish sticks were considered a pretty rare dinner at home..

Thirty-five years ago “fresh” North Dakota seafood came frozen in a box and was usually deep fried. One of my fondest memories of dining out was the occasional trip to the bowling alley in Williston and eating “shrimpos.”

It seems that fish in some North Dakota waters have the same appetite for shrimp, though they are fortunate to have a ready supply every day instead of only on special occasions. Freshwater shrimp are a key part of the aquatic food chain wherever they exist, feeding both large and small fish to a point where they may not show an interest in angler offerings because they aren’t hungry.

North Dakota is home to three freshwater shrimp species, gammarus, hyalella and mysis. The latter is an introduced species stocked in Lake Sakakawea in the early 1970s to add to the forage base. This species never really took off, and if any remain in the reservoir they are not abundant.

While the gammarus in Devils Lake garner much of the freshwater shrimp attention in the state, the smaller hyalella are found in more waters. Both, for certain, are important links in the forage base in those fisheries in which they are found.

Out of all North Dakota waters, Devils Lake is best recognized as home to these half-inch, nearly translucent creatures also known as gammarus, scuds or sideswimmers, which describes the way they propel themselves through the water.

It’s well-known that perch, walleye and pike in Devils Lake are healthy, in fact, that’s probably an understatement. Some anglers may argue that the actual catching of fish on Devils Lake may not rival the health of the fishery, but perhaps that’s to be expected considering the abundance of shrimp and other natural food sources along with a high water volume

In fact, a case of “fish biting on bare hooks” is often a sign of an unhealthy fishery, with hungry fish because of a lack of naturally occurring forage. Think of a trout pond at a sportshow and you’ll better understand the comparison.

Fisheries biologists monitoring Devils Lake game fish say the scud population is high on the list of reasons why the fish of Devils Lake are so healthy. Yellow perch, walleye and other species have little trouble finding and filling their stomachs with freshwater shrimp. While this hearty forage base is competition for the best angler, at the same time the long term viability of the fishery would be difficult to sustain without it.

But what do the shrimp need to survive? Freshwater shrimp are known to feed on all kinds of things. Often these tiny creatures browse on microscopic plants, animals, algae and other organic debris. Shrimp are at the front of the food chain. If a fish dies, freshwater shrimp are right there to turn the decaying flesh into energy that other fish will consume.

The recipe to create and maintain a healthy fishery is intriguing even to a biologist. Every facet is important.

So the next time you hear an angler at a fish cleaning station discussing a belly full of shrimp, it just might be the fish… and not the angler.

Leier is a biologist with the Game and Fish Department. He can be reached by email:  dleier@nd.gov