October 26, 2015
Only during the last twenty years have we begun to understand the science of muskie behavior. The more we've learned, the more we've wondered. Where do muskies spawn? Where do they spend the summer, winter, and autumn? How does water temperature affect their behavior? Do they wander aimlessly or set up ambush spots? Does forage affect distribution? Do they behave differently in large lakes than in small ones? And how do they interact with other predators?
Those are just a few of the questions muskie scientists and muskie anglers seek to answer. We've selected five independent tracking studies conducted on some of the best muskie waters in North America. While we won't answer every question, the results do synthesize into easy-to-understand concepts.
Our five selected muskie lakes read like a batting order in an all-star game. Leech Lake, Minnesota's most important muskie fishery. West Okoboji, in northwestern Iowa's popular Great Lakes region. Lake Scugog, from the heart of southern Ontario's famous Kawartha Lakes system. And Moose and Black lakes in Wisconsin's Chequamegon National Forest, part of the famed Chippewa River system.
These waters share many physical and aquatic characteristics, yet each is unique. Sprawling across more than 100,000 acres, Leech Lake is a giant compared with 115-acre Black Lake, 1,500-acre Moose Lake, 3,400-acre West Okoboji, and even 14,000-acre Lake Scugog. Also, West Okoboji's muskies are stocked fish, first introduced over 35 years ago, while muskies in the other study waters occur naturally.
Each lake's morphometry and trophic status — age of a lake basin and its age in terms of organic productivity — varies, too. The physical appearance of West Okoboji and its deep water (maximum depth 125 feet) suggest that it's a young lake. But West Okoboji is a fertile lake, just like the flat, shallow, rich, weedy water of Lake Scugog. Leech Lake is mainly middle-aged, by contrast, offering sections ranging from medium-fertile to soupy-old.
But comparisons don't end there. Pike occur naturally in Leech Lake and West Okoboji, but are absent in Moose and Black lakes, and only now are entering Lake Scugog. Walleyes, bass, suckers, bullheads, perch, and assorted panfish, on the other hand, are present in each water.
The stars in this game aren't the lakes, so much as the select group of muskies that provided a glimpse into their life histories — 14 muskies in Leech Lake, 20 in Lake Scugog, 11 in Moose Lake, 9 in West Okoboji, and 7 in Black Lake — all caught either by angling or trap netting. Biologists either fixed external radio transmitters to the fish or anesthetized them, made a small incision in the belly, and implanted a tiny radio conductor. The incisions were closed and the fish allowed to recover, then were released, usually where they had been captured.
They were tracked for varying periods, ranging from one year in Leech Lake to almost two years in West Okoboji. Biologists following the fish plotted their daily and seasonal movements, and in some cases charted specific habitat and water temperature. After tracking the fish night and day, summer through winter, over thousands of hours, we find . . .
There's No Place Like Home
Muskies are homebodies, whether it's spring when they spawn, summer, or under three feet or more of ice in winter. And they're faithful to these territories, returning year after year, so long as they live. This explains why good muskie spots often are hot for decades, if anglers practice catch and release. It also explains why it's possible to return to a spot where you raised a big muskie and eventually catch it.
But muskies don't have a single home range, but at least three — one for spawning, one for summer, and another for winter. In general, these seasonal home ranges are located in different parts of the lake.
But not all muskies have read this part of the rule book. Those in Black Lake wander more. And muskies in Lake Scugog faithfully return to their summer homes where they also stay throughout much of autumn. Leech Lake muskies, meanwhile, exhibit classic seasonal behavior.
Why the differences? Well, Black Lake is tiny — smaller than the home range of many Leech Lake or West Okoboji fish. So a Black Lake muskie may use almost the entire lake to meet its multiseasonal needs. In Lake Scugog, on the other hand, muskies return to well-defined summer homes, which are relatively small on this shallow lake, and they stay there well into fall, when their counterparts in other bodies of water are roaming. Why?
"Both smaller home ranges and the use of summer home ranges in fall," says Richard Stronks, Ontario Ministry of Natural Resources biologist in charge of the tracking, "could be attributed to the abundance of forage fish in Lake Scugog. If prey are abundant and close by, a predator doesn't need to expend as much energy searching."
And that is precisely what the muskies in West Okoboji, a couple thousand miles to the west of Scugog, confirmed. They faithfully returned to their summer grounds, which ranged from 85 to 975 acres. But Okoboji muskies used this summer habitat in a unique way.
Home S-Weed Home
Early in the season, before the weeds were firmly established, the muskies roamed the deeper, cooler, clearer, more open sections of their summer territories — places where muskies anglers typically don't expect to find them. Until early July, over 75 percent of the locational fixes pinpointed West Okoboji muskies in locations lacking vegetation. Instead, they were open-water predators.
Then by August, the hottest part of summer, they moved shallower, into warmer, more turbid water where visibility was half what it was in open water. In fact, 78 percent of the fixes were associated with weeds, especially the weedline and weed pockets, while only 37 percent of the lake basin contained vegetation. They remained in these heavily vegetated sections of their summer home ranges until well into November.
Michael Dombeck, who tracked the fish in Moose and Black lakes, observed the same phenomenon. He frequently found muskies in the shallows in the middle of summer, when water temperatures exceeded 80°F, and much cooler and deeper options were but a tail swipe away.
"This shift in behavior patterns," say Marilyn Miller and Bruce Menzel, researchers who tracked the muskies in West Okoboji, "may reflect a feeding strategy in response to seasonal changes in environment and prey availability.
"Our angling survey results," they say, "imply that Okoboji muskellunge are most vulnerable to angling during late summer and early fall. Their relatively small areas of preferred habitat at this time are easily located, either by visual sightings or with electronics. Furthermore, these areas are effectively fished by casting and speed-trolling. Harvest of the muskellunge population is seasonally maximized when paths of fishermen and fish intersect."
When Paths Cross Opportunities Meet
What Miller and Menzel are saying is that muskie anglers, at least on West Okoboji, could increase their chances of catching fish by changing their pattern of fishing. Instead of beating the weeds from early in the season until July, they should ply open areas of the lake with techniques better suited to roaming fish.
I'm reminded of Dr. Mark Ridgway, an authority on smallmouth bass ecology and management, who tracked smallmouth in Ontario's Lake Opeongo and discovered that the fish established large summer traplines, rather than tightly confined home ranges. They covered these traplines every day, routinely swimming 6, 7, 8, or more miles.
Ridgway said, "we'd often talk to anglers anchored off a point or a bar, and they'd tell us the fish were starting to turn on.
They weren't turning on, however, but arriving at that particular spot in their travels." I'll bet my favorite Suicks that many a West Okoboji muskie angler has similarly noted in July that the big fish are at last turning on.
But midsummer isn't the only time to re-evaluate muskie hunting strategies based on the results of these tracking studies. The first week or two following opening day, most folks concentrate in and around shallow, weedy back bays and marshes, hoping to way-lay a lingering postspawn fish — a good strategy without pike in the lake.
When pike and muskies share a body of water, as in Leech Lake, they put space between one another in spring. If only pike swam in each of our study waters, they would generally spawn in the best sheltered, vegetated back bays and coves — classic spots.
But when muskies and pike share a lake, they distance themselves at ice-out. Pike spawn earlier, typically as soon as the ice honeycombs and melts. Muskies, on the other hand, spawn when the water warms. So, if they used the same spawning sites, the newly hatched muskie fry would be devoured by the much earlier hatching and therefore older, larger, and more voracious young-of-the-year pike.
As Minnesota biologist Bob Strand demonstrated in his tracking work on Leech Lake, muskies spawned well offshore, in three to six feet of water, over beds of skunky-smelling sandgrass or chara. A number of other field investigations have documented this species-split phenomenon, most notably Dr. Ed Crossman's pioneering muskie work in the early 1970s and Bernard Lebeau's recent monitoring of muskies in northwestern Ontario.
Regardless of the location or the study, though, if a lake has a natural population of pike and muskellunge, pike use marshy back bays and coves. That's why biologists on pure muskie lakes like Scugog are concerned with unnatural introductions of pike. By the time the muskies learn to avoid pike on prime spawning grounds, it could be too late.
Individualistic Top Predators
One of the most significant observations from these tracking studies is that muskies, as many anglers have long believed, are predictable. And yet, just when a pattern seems to emerge, another study of a different group of muskies proves the theory wrong.
These fish are top predators and, as such, act in unpredictable ways. Bob Strand said of Leech Lake muskies, "We observed differences among individual fish locations (habitat) during the same time period, and also variations in movement, suggesting individuality among the tagged muskellunge."
Individuality? Just another way of saying the muskie's a character, one that stirs imaginations, roots deeply into our very being, and gnaws at us until we're hopelessly obsessed.
Does Catch and Release Work?
Surprisingly, as we were reviewing these tracking studies, we arrived at two unexpected conclusions. The first confirms what many muskie researchers and anglers have long suspected: Even in the best lakes, rivers, and reservoirs, muskies are never plentiful. The second is that catch and release works.
On Leech Lake, Bob Strand and his researchers caught 14 muskellunge on traditional presentations. Then they surgically implanted lithium radio transmitters in each of the fish. Results? The muskies survived the procedure so well that years later, when they were reexamined, the wounds were almost undetectable.
"The survival of all the angler-caught fish, additionally subjected to implant surgery," Strand says, "strongly suggests that catch and release of muskellunge is a realistic management option." Similar high survival rates in the other tracking studies demonstrate that muskies properly handled can be released to live and fight another day. Indeed, given the scarcity of muskies and their vulnerability to angling, catch and release is critical.
When researchers tag limited numbers of fish within a population, like the minuscule numbers followed in each of these tracking studies, it is expected that none of the fish would be recaptured. But that was far from the case in these studies
In fact, of the fourteen radio-tagged fish in Leech Lake, eight were subsequently captured by anglers. Similarly, thirty percent of the muskies — three of the nine fish — tracked in West Okoboji Lake were caught by anglers, while one of the eighteen fish followed in Moose and Black Lakes was caught. For a muskie, those are not good odds for survival.
Illustrations are remarks pulled from limited edition muskie prints by artist Terry Doughty, 414/453-1620.