The March 1995 issue of the In-Fisherman detailed a tracking study in which three walleyes caught in Ten Mile Lake in northern Minnesota were intensely scrutinized over a 24-day period during midsummer 1994. Ten Mile Lake is a deep, clear lake of about 5,000 acres. These fish were implanted with ultrasonic transmitters containing long-life batteries and were tracked several times throughout each 24-hour period. Each of the walleyes exhibited a characteristic behavior pattern during the summer observation period.

Summer Movement--Walleye #276, which was 21 inches at capture, spent most of its time within a 1.5-mile-long home base on a side of the lake containing classic walleye structure--rocky reefs and underwater islands near deep water. Frequently, it made forays into open water (suspended movement) over 100 feet deep, where it presumably fed on dwarf ciscoes that swarm by the millions in Ten Mile Lake. On Map #1, its summer range is shaded.

Walleye #294, also somewhat over 23 inches at initial capture, was a stay-at-home. Over the three-week summer observation it spent almost all of its time in an area dominated by deep weed-covered flats (shaded area on Map #1). Only twice, during dramatic shifts in weather, did it briefly leave its home range, each time returning within 24 hours.

Walleye #285, which was 23 inches long when tagged, was a wanderer that during the course of the summer study visited most parts of the lake. It had no real home range, and its summer movements are summarized by the lines on Map #2.

Winter movement--Walleye fisherman often wonder what happens to these fish when the lake freezes over. Do they choose a deep hole where they ride out the long winter, or do they maintain their summer lifestyle, albeit at a slower pace? These and many other questions remain to be answered. Having three walleyes with well documented behavioral patterns in hand, however, was just too good an opportunity to miss.

Fortunately, Buzz Converse, an intrepid year-around resident on Ten Mile Lake, volunteered to continue the tracking study during winter. This was no task for the faint-hearted. Locating a single fish typically requires drilling a dozen holes, and each time the hydrophone is lifted up from the ice hole it becomes coated with a layer of ice.

The winter study began in late December, after the ice was thick enough for safe crossing. It was discontinued in late January when the ice became 30 inches thick and air temperature dipped colder than most of us care to endure. Two additional readings were made in mid-March, before the ice became honeycombed.

During the December-January observation period, Walleye #276 was found in its summer home range, first picked up on a rockpile (#1) not far from deep water. One day in late December it crossed the lake to a deep rockpile far out in the lake (#2). But the next day it swam back to its home range on the other side of the lake (#4). Two weeks later, it was spotted away from its home range off the point where it was originally caught the previous summer (#5). Several days later it was back on the rockpile off the point where it was first spotted in late December.

In mid-March, #276 was picked up far from its home range off the edge of a long shallow bar (#6). Two days later it had moved into a 40-foot-deep hole between the bar and shore (#7).

Walleye #294, for the most part, abandoned its restricted summer home range and during January moved in a semicircle from the northwest to the east side of the lake (#1 - #9). It seemed to alternate holding between sloping banks or off the ends of classic hard-bottom points. In mid-March it was located at the far southern end of the lake along a steadily sloping sandy bank (#10 - #11) in 40 feet of water.

During January, Walleye #285 didn't live up to its summer-wandering ways. Each time it was spotted, it was cruising a restricted region off a point on the south shore of the lake (shaded area on Map #2). Its January range was dominated by rocky underwater islands and points, and much of the time it was in 20 feet of water. By mid-March wanderlust had again struck, and it was spotted far up the northeast side of the lake in about 20 feet of water (#1). Two days later, it had moved about 2 miles to a relatively featureless sloping bank in the southeast corner of the lake (#2).

The remainder of the saga of the wandering walleyes remains to be told, but we've learned some lessons from this tracking data. Most important is that we shouldn't generalize from the behavior of a single fish. Each fish had its own winter range and exhibited its own pattern of movement. The fish (#285) that was most active during the summer study travelled little during January, spending most of its time on classic walleye structure. By March, though, it had resumed its wandering ways.

The other two fish moved around during January, but in regions not coinciding with their summer ranges. In winter, all fish showed a greater tendency than in summer to relate to long, featureless, sloping banks. And they were not found in the deep central part of the lake where they fed on ciscoes in summer. By mid-March, all of the fish had moved to locations different from their January haunts, but the observations were too restricted to generalize about movements.

With abundant forage fish throughout Ten Mile Lake, and with presumably relatively constant under-the-ice conditions, we wonder why the walleyes traveled at all. Too, one of the mysteries remaining is how a walleye's muscles can contract vigorously enough to swim at all in 32F to 39F water. Why too do some fish, such as walleyes, pike, and lake trout, remain vigorous in cold water, whereas other fish, such as bass, become more nearly dormant. Recent discoveries in the field of muscle biology may soon provide answers to how fish function in cold water.