Studying Walleye Diets on Devils Lake

Jason Breeggemann didn’t put many walleyes in the boat Wednesday morning, but few people have handled more fish on the big lake this summer.

Hundreds wouldn’t be an exaggeration.

A doctoral student at South Dakota State University, Breeggemann is fishing for information, you might say. He’s overseeing a study that aims to learn more about what Devils Lake’s fish are eating and how it affects their growth rates.

The big word for this relationship is “bioenergetics” — there’s more to it than diet, but you get the gist — and the fieldwork Breeggemann is conducting will allow him to build computer simulations to determine whether certain prey species result in bigger fish than other types of forage.

Does a walleye that eats mainly yellow perch, for example, have the potential to grow larger than a walleye that lives on freshwater shrimp, an abundant invertebrate species in Devils Lake?

Do fish grow faster during certain times of the summer?

That’s what Breeggemann aims to find out once he’s collected the data and crunched the numbers.

“What we’re doing is developing a baseline model for Devils Lake — this is how they grow based on what they’re eating,” Breeggemann said. “Once we have that baseline, we’ll be able to adjust prey species and see how that is going to affect growth.”

That baseline also involves knowing how much energy various prey species provide. In the same way a fatty hamburger has more calories than a lean turkey sandwich, no two fish foods are alike.

“Say the diet is 90 percent amphipods (freshwater shrimp), what would happen if we were to switch to 90 percent yellow perch — how would that affect growth rates and growth potential?” Breeggemann said. “We’ll look at that based on changes in diet.”

Link (Via: Grand Forks Herald)

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