May 07, 2019
By Rob Neumann
Kinkaid Lake in southern Illinois experiences mild winters and long, hot summers, comparable to the climate of central Arkansas. Surface temperatures can reach 86°F during extended periods in summer. This 2,300-acre reservoir supports a popular muskie fishery, and is an excellent venue to study muskies at the southern edge of their range.
Researchers at the Fisheries and Illinois Aquaculture Center at Southern Illinois University tagged muskies with temperature-sensing transmitters to determine seasonal movements and habitat use of adult muskies and to examine behavior during the potentially stressful summer period.* Fish were located every several days, and at each location, depth profiles of temperature and dissolved oxygen were taken and used to estimate fish depth, based on fish transmitter temperature. Habitat type also was recorded as open water, standing timber, vegetation, or a combination of vegetation and standing timber.
Thermal stratification occurred from mid-May through mid-November at depths from 14 to 21 feet. Summer surface temperatures ranged from 81°F to 86°F. Dissolved oxygen was limiting (less than 3 ppm) below the thermocline from June through September and increased through October until the lake was mixed by November.
From October to December, body temperatures of muskies generally matched the surface temperature, as the lake was mixed during that time. In winter, body temperatures, from 39°F to 52°F, were slightly cooler than surface temperatures. From June through September, muskies maintained body temperatures of around 77°F, inhabiting depths associated with the thermocline where dissolved oxygen was suitable.
In July and August, muskies often inhabited temperatures that are considered stressful for coolwater fish, or were located at depths with low dissolved oxygen, presumably to avoid warm water. Fifty percent of muskies were located in dissolved oxygen levels less that 3 ppm in summer. Some were found in depth zones where oxygen levels would occasionally drop to 1 ppm. Twenty percent of the fish occupied water at or above 82°F. Muskies in water that warm typically returned to cooler, deeper water after short periods.
Some muskies established seasonal home ranges, often overlapping with other muskies. Other muskies wandered throughout the lake most of the year. Wanderers seemed to temporarily linger in areas frequented by other muskies before moving to other high-use areas.
In late February and early March, all tagged muskies moved to a shallow creek arm area. Some fish moved farther up into the creek and remained there for several weeks to as late as June. Movements overall tended to be highest in February and lowest in July.
In fall, muskies had a preference for combined (timber and vegetation) habitat, and preferred timber areas in winter and spring. Vegetation and combined cover were selected by muskies in summer. When the lake was stratified, muskies most often suspended at depths of around 11 to 12 feet.
*Beck, P. A., and R. C. Brooks. Seasonal movement and habitat use of muskellunge in a southern Illinois reservoir. Fisheries and Illinois Aquaculture Center Research Report, Southern Illinois University.
Pike Habitat Use
Outside of the Far North, big pike in lakes can be difficult to locate in summer. They seem to disappear from shallow environs and move to deeper water, either along deep weededges where they feed on perch, sunfish, and minnows, or open water where they hunt for pelagic baitfish like whitefish and ciscoes. Location appears to be affected by water temperature, dissolved oxygen, and prey preferences and availability.
To help solve the summer location puzzle, Minnesota DNR fishery biologists tracked pike to determine selected depths and temperatures.* Pike were divided into large (greater than 28 inches) and small fish groups. Water temperatures were continuously measured throughout the water column at the deepest part of each lake, and depth profiles of dissolved oxygen were made weekly.
Individual pike were flexible in depths used within seasons and between years, although significant patterns emerged. Pike had the deepest movements and more fully used all available depths during the spring and fall turnover periods when dissolved oxygen in deep water increased. In summer and winter, depth selection was affected by low dissolved oxygen in deeper water.
As upper layers warmed during summer, large pike tended to follow the thermocline to cooler water. Models predicted that pike preferred water temperatures between 61°F and 70°F in August when temperatures up to 82°F were available. Small pike were found in warmer, shallower water in two lakes that had dense water lilies. In the third lake without similar vegetation coverage, smaller pike were often in deeper, cooler water. The researchers suggest that temperature is secondary to shallow vegetation in affecting habitat use of small pike.
One of the test lakes had numerous cold groundwater inflows near the shoreline in water less than about 3 feet deep. The researchers found no evidence that large pike took advantage of these shallow pockets of cold water.
*Pierce, R. B., A. J. Carlson, B. M. Carlson, D. Hudson, and D. F. Staples. 2013. Depths and thermal habitat used by large versus small northern pike in three Minnesota lakes. Trans. Am. Fish. Soc. 142:1629-1639.
Tiger Muskie Movements
Fishery biologists of the Washington Department of Fish and Wildlife implanted transmitters into tiger muskies to track their long- and short-term movements in Newman Lake, Washington.* This reservoir near Spokane is 1,200 acres and has an average depth of 19 feet and maximum depth of 30 feet. Thirty muskies between 22 and 45 inches were outfitted with ultrasonic transmitters and tracked over two years.
Tiger muskies tracked bi-weekly had greater movements during the winter-spring (November-June) period than in summer-fall (July to October). About 90 percent of bi-weekly movements were greater than 100 yards. While movements followed a similar seasonal pattern as found at Mayfield Reservoir in a previous study, Newman Lake fish moved about twice as far between observations, suggesting that behavior of tiger muskies can be lake-specific.
Short-term movements were determined from hourly observations over 24-hour periods. A range of behavior was observed among individual fish. Some tiger muskies occupied short stretches of shoreline or stayed in a certain bay, while others traveled long distances. One fish moved just under 10 miles in 24 hours. The same fish traveled almost 1,000 yards in 15 minutes — an average speed of 2.9 mph.
Seventy percent of muskies were found in water greater than 7 feet deep in summer and fall. In spring, 43 percent of the fish occupied depths less than 7 feet.
*Osborne, R., M. Divens., W. Baker, and Y. W. Lee. 2012. Behavior of tiger muskellunge in Newman Lake, Washington determined by ultrasonic telemetry. Washington Department of Fish and Wildlife Report FPT 12-01.
Tracking Pike and Muskies
Calm and Sunny
For walleyes, especially in the Summer Peak, bright and glassy conditions can disrupt the shallow weed bite in clear lakes, ushering large fish into deeper water. However, smaller, eater-sized 'eyes can still be caught along shallower weedlines. Deep bass remain active, but their shallow counterparts slide under docks or other shady objects such as downed trees. The shade offers camouflage, cool conditions and protection from the sun's UV rays. Photo: Fish were hiding in the shade on the Fox River.
Downpours of biblical proportions can yield phenomenal action for a variety of gamefish — provided conditions are safe to fish in. During the deluge, choose active presentations tailored to aggressive fish, which often roam much shallower water — or ride higher in the water column — than they would under bluebird skies. Once the rain subsides, fish often follow rising water into newly flooded habitat. If the water has dirtied due to runoff, seek out the clearest conditions available. Also pay attention to water temperature, being sure to target inflows with temps appropriate to the species you're seeking. Large pike, for example, favor cool water and follow chilly inflows into skinny water. However, when panfish or bass move shallow seeking fast-warming water in spring, cool runoff is a killer. Photo: This was a great night on the water.
Scorching summer hot spells can test our endurance, along with our skills. Rising water temps, a shrinking thermocline, and a full-court press from unfettered sunshine collide to drive fish into deep water, shaded areas, and thick vegetation during the day. If fishing the night shift is an option, take it. Otherwise, focus on prime times early and late, or take advantage of the arrival of wind, waves, and cloud cover — which can spark spikes in fish behavior. As water temperatures rise, finding icy inflows from spring-fed streams or seeps can produce epic catches of fish that like keeping their cool. Giant pike, anyone? Be forewarned, in extreme swelters, die-offs of curly-leaf pondweed coinciding with hot temps and a lack of wind can drive down a lake's oxygen levels, causing widespread summerkill of bass, panfish, walleyes, pike, and other species. Photo: 95 in the shade on Lake Winnebago.
A gentle drizzle with little or no breeze is a great time to be on the water. Reduced light conditions ignite feeding behavior in everything from trout to walleyes, while the rain keeps fair-weather fishermen on shore. On the bass front, this can be a perfect time to throw a one-two punch of jerkbaits and topwaters. In-Fisherman friend and veteran bassman Scott Bonnema tosses a big, suspending slashbait like the size 10 Rapala X-Rap in calm conditions, and chugs a Skitter Pop when a light wind mixes with the rain. Photo: Alaskan sockeye in a lovely light spritz.
When cloudy skies reduce light penetration, predators often go on the prowl, especially in shallow water. Large pike, for example, commonly become active in relatively shallow shoreline weedbeds that produced only small fish in sunny weather. As a general guideline, ideal lighting at noon on a cloudy day mimics the light levels experienced early and late in the day in clear weather. Active fishing presentations with larger baits often score the best catches, particularly in shallow feeding flats or other areas where schooling fish are feeding. Photo: Overcast on Gull Lake.
Post Cold Front
Associated with bluebird skies or wispy clouds, a rise in barometric pressure, and cooling temperatures, the post-frontal landscape can be one of fishing's toughest nuts to crack. For predators such as bass, pike, and walleyes, cabbage-crowned points and outside weedlines lying in 15 to 18 feet of water often hold groups of fish — though perhaps not active schools. Casting or trolling deep-running crankbaits such as Bomber's Fat Free Shad or the Rapala DT16 are good ways to locate fish. If you crank up one or two catches from a spot, be sure to try a slower presentation, such as a jig and softbait, to milk a few more bites from the area before moving on. When you have a choice, focusing on flowing water is another solid option, since river fish are often less affected by fronts than their lake-run cousins. Photo: Deep cranking.
Ouch! A skyrocketing barometer following a major cold front is often associated with the worst possible fishing conditions. While debate swirls about whether barometric pressure is actually the culprit, there's little argument that rising pressure often coincides with a lake's fish developing a serious case of lockjaw. Fish often sulk tight to bottom or cover, in loose groups rather than schools, and turn up their noses at presentations that worked so well a day or two earlier. Compensating tactics range from finessing small baits to fishing large lures fast, in hopes of triggering reaction strikes. Photo: Front went through during the night on Bays de Noc, headed east on the horizon.
Whoever said change is good had never fished during a long stretch of fair weather. Veteran multispecies angler and Minnesota Department of Natural Resources fisheries manager Roger Hugill says an extended period of stable weather allows fish to find their comfort zone — that is, a balance of the right water temperature, oxygen level, and other factors. 'This fuels a nice, steady bite, which is something we all like to see, ' he grins. Photo: Bays de Noc under stable conditions.
Gusty conditions can make boat control interesting, but the waves they generate often flip the feeding switch for bass, walleyes, and other gamefish. For example, two to three-footers rolling over a shallow rocky reef or weedflat trigger big pike to move shallow from nearby deep water. Largemouth bass living in the vegetation also turn on, although it can be a different case on the rocks. Sometimes, smallmouths that ruled a reef in calm conditions exit the area when big pike take center stage. For bass, pike, walleyes, and more, a suspending jerkbait slashed just beneath the wave trough can be deadly, as can Colorado-blade spinnerbaits, whose flash and thump rise above the din of heavy seas. Photo: Great conditions for an afternoon ride on Leech Lake.
If you could choose one time to be on the water, this would be it. While the pressure debate extends to whether a falling barometer affects fish behavior — or simply coincides with other conditions that do — many diehard anglers swear by it. In fact, In-Fisherman friend Bob Samson, a science teacher, multispecies fan, and devoted student of the barometer's affect on fish behavior, swears that even slight dips in pressure throughout the day can trigger bursts of feeding activity. Major increases coinciding with the approach of a large storm can coincide with sheer suicide bites. In-Fisherman art director Jim Pfaff and guide Billy Rosner experienced such action on Minnesota's Lake Vermilion, when muskies and trophy pike went on a rampage prior to the arrival of a mega-storm that dumped up to nine inches of rain on the nearby city of Duluth, causing major flooding.