What are muskies eating? Studies aim to find out

Minnetonka, Minn. — DNR Fisheries officials say, following a muskie-dedicated symposium last week, they’ll soon have more information to offer.

The proposed stocking of muskies in the metro’s Big Marine Lake, southern Minnesota’s Fairmont chain (Amber, Hall, Budd, Sisseton, and George), Gull Lake in the Brainerd area, and one of three lakes in Otter Tail County (Franklin, Lizzie, or Loon) also has captured the attention of the Minnesota Legislature this session.

Last week, the topic of the diet of the muskellunge was one of many items discussed at the Hugh C. Becker Muskie Symposium – attended by fish biologists across much of North America – in Minnetonka. Steven Kerr, retired from the Ontario Ministry of Natural Resources, talked about his own study of what muskies eat.

“The vast percentage of (a muskie’s) diet is comprised of fish,” Kerr said during his presentation of findings from “Feeding Habits and Diet of the Muskellunge.”

Further, he said, “Feeding activity increases as you go through the season.” That’s also probably why muskie fishing at times tends to improve in the fall.

Those items aside, the concerns in many areas are how muskies and their appetites affect other fish, like walleyes and smallmouth bass.

According to the report by Kerr, who was commissioned to do the study by the Ontario MNR, as well as Muskies Canada, Inc., the study was done because in general “there are few definitive studies to quantify impacts (if any) of muskellunge on other fish species.”

But, the report summary says, “There is very little evidence to indicate that muskellunge have a significant negative impact on populations of other popular sport fish species including walleye, largemouth bass, and smallmouth bass. In fact, there are numerous instances where these fish species successfully co-habit the same water body.”

That said, the study found, “Other fish species can have negative impacts on the muskellunge. Northern pike are known to have a competitive advantage over muskellunge where they co-exist. Young muskellunge are also subject to predation by other fishes including largemouth bass, yellow perch, rock bass, and walleye.”

Kerr spoke for 20 minutes at the muskie symposium as he recapped the study. He also pointed out that muskies are solitary predators, they’re “sight-oriented,” they ambush vs. pursue their prey, and they have a diverse diet with seasonal variations.

Once a muskie has gotten to a particular size, fish comprise 90 percent of its diet, it can be cannibalistic, and that muskie would rather have one big meal rather than several small ones.

After three months of research, Kerr said, “I was unable to find any evidence of muskies having any significant impact on those (bass and walleye) species.”

Other factors, according to the report, include the size of a water body and the composition of the fish community: “Large water bodies and those waters having a diverse forage fish community seem to be relatively unaffected by the presence of muskellunge,” the report says. “The presence/abundance of soft-rayed fish species (suckers, ciscoes, whitefish) likely reduces the predation on other resident fish species.”

Kerr also noted that a variety of other items were found in the stomachs of studied muskies – anything from crayfish to frogs to snakes to ducklings to small mammals like mice and shrews.

Kerr said stomach contents often aren’t identifiable, that what they find is a “big pile of mush.” He said new tools are being developed to better identify said “mush.”

It’s also become apparent during his studies that there’s a greater need to improve the public’s perception of muskies, primarily through increased educational efforts.

The Minnesota DNR says it intends to do that as it moves toward the stocking of new state waters, as spelled out in a departmental long-range plan that called for stocking eight new waters with muskies by 2020. Three thus far have been stocked with muskies.

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