New fisheries science shows that big muskies eat almost anything

Where does a giant silverback gorilla sleep?  Anywhere it wants. What does a 50-pound muskie eat?  Well, you get the drift.   

We recently sat down on our DOC TALKS FISHING podcast and chatted about what muskies eat with biologist Kamden Glade, who studied the diets of muskellunge, walleye, northern pike and largemouth bass using gastric lavage. That’s the same procedure that hospital emergency rooms use to pump out the stomachs of patients, like a youngster who may have inadvertently swallowed a bottle of aspirin. He then analyzed the contents, sometimes using DNA if the items were partially digested and unidentifiable.

Here is a small sampling of what Kamden discovered. You can listen to the full podcast HERE.

On why Kamden undertook the research and the questions he wanted to answer.

• There were different factors at play but the underlying question was how do these big predators, with mouths full of huge teeth, affect other fish?

• The overarching question is what do the diets of these four predator species and especially muskellunge look like?  Are they eating the same things, because if there is a high level of overlap that could lead to competition, which could have other effects down the line in terms of reproduction and growth.

• The other big one that a lot of people always want to talk about is are they eating each other? This is especially true if muskies are eating walleyes.

How did Glade collect the various fish that he sampled?

• Electrofishing was definitely the most effective and our preferred method if we could get away with it. It lets us sample the most amount of fish most efficiently. The fish stay alive, which is a key aspect, especially when you’re looking at muskies because they occur at such low population densities and they’re (often) stocked. So they’re pretty valuable in these lakes where they’re occurring. We also used trap nets in the spring.

On some of the fascinating things that Kamden discovered about muskie diets and feeding patterns.

• Their diets were kind of all over the place. There is one fish that sticks out, kind of the poster child of this, that had 101 different individual prey fish in its stomach.  And it was mostly yellow perch, 97 of them were yellow perch, but then there were also parts of two bullheads, a sucker and a sunfish in the stomach as well.

• In other cases you’d pull out a pike and a cisco or bullhead and some invertebrates. Just a weird combination of things from the musky stomachs, whereas the other three species definitely tended to specialize a little bit more on what they were eating.

• For muskies, perch were the most important item, but they only accounted for about a quarter of the diet.  Suckers and invertebrates each accounted for about 10%. And then bullheads, northern pike, bass and sunfish all made up about 5% of the diet.

• Pike and walleye had the most similar diets of any two species pairs of the four that we looked at. And they ate primarily perch, sunfish and crappies. The exact proportions of those three groups were different depending on the lake.

On why walleyes showed up so little in the stomachs of muskellunge.

• There were lots of times where, you know, we go through and hit a pod of walleyes and we’d scoop a bunch up. And then not 10 yards down the weed bed or the breakline, there’s a big muskie hanging out and we get that one too.

• In terms of why we’re not seeing more walleye in the stomachs, it could be that muskies are actively avoiding walleyes. Like you said, they’ve got lots of sharp spines and even their scales and gills can be pretty sharp and rough. I know I’ve gotten poked and scratched multiple times so I can’t imagine that’s a very pleasant experience for a muskie.

• But it’s also possible that walleye are just better at avoiding being eaten than some of the other species. Walleye are predators just like muskies. They’re built a little bit differently, but in both cases they’re kind of built for some really quick bursts of speed that help them capture their prey. And so that might be just enough to help them get away from muskies, almost as much as it is helping them capture their own prey.

How is the diet of “memorable size” muskies different from smaller muskies?

• So this is really interesting and it makes a lot of sense when you look at it one way and then it gets really confusing when you look at it the other way.  Generally speaking we saw that smaller muskies tended to consume more perch, bass, and sunfish. Which kind of makes sense, those tend to be on the smaller end, especially in a lot of the systems we were in.

• Bigger fish tended to consume more suckers, and that pattern makes sense as well. You know, a big fleshy baitfish like that, you need a little bit bigger mouth, a little bit bigger gape size to be able to swallow those fish. Where it gets goofy is we also saw that larger musky were more likely to consume invertebrates than some of the smaller fish.

On why muskies eat so many northern pike in certain lake types

• If you think about, say a 20-inch pike is kind of average for the sizes that we saw, maybe a little bit on the high end, but if you look at that, it’s just a giant foot-long hot dog with fins that’s swimming around in the water. There’s nothing to stop it from just sliding straight down into your stomach once you get it turned around.

• Those pike can be one of the most abundant other fish species in the lake. And so that just makes sense that a musky is going to swim by and grab one, as opposed to some of the other things that we saw in the stomachs.

We got Kamden, who is an accomplished angler, to tell us how his diet study results have changed the way he fishes for muskie. We can’t spill all the beans, you’ll have to listen to podcast for those details, but here are a couple of teasers.

• I guess the first thing I would say is that it’s not always worth the shoulder ache to throw the big baits all the time. We did see that bigger fish were more likely to eat big prey fish. But there were still lots of really large muskies that were eating three inch perch, five inch sunfish.

• Good spots are really good spots and there can be multiple fish on a good spot. So I’ve kind of translated that into my angling, where if I’m contacting fish, it’s going to make me much more likely to stick in a similar area rather than bouncing around.

To listen to the full fascinating podcast with Kamden Glade click HERE.