Lake Minnetonka Special Assessment 2003 Status of the Fishery A special assessment of Lake Minnetonka occurred from June 9-27, 2003. Although the lake has fisheries of many important game species, this survey was undertaken to target walleye, northern pike, and yellow perch populations using only gill nets. Species such as bluegill, black crappie, largemouth bass, and muskellunge, while sampled incidentally with gill nets, are better sampled with other gears used during more-complete survey types. Such information can be found in documents such as the internet-posted 1997 Minnetonka lake survey (in “Lake Finder” section of MN-DNR web site). Lake Minnetonka’s next multiple-gear survey is scheduled for 2007. Walleye sampled in 2003 averaged 16.5 inches and 1.97 pounds. Sixty-five percent of walleyes caught were larger than 15 inches. Walleye catch per gill net was 3.3, below the median value this lake type (6.6 walleye/gill net) and the 2002 special assessment (5.2 walleye/gill net). Minnetonka’s walleye gill net catch values have typically been below the lake-type median, except in 1999 and 2000, when per-net values were, respectively, 8.8 and 7.4. Walleye fingerlings are scheduled for stocking, according to Lake Minnetonka’s management plan, in alternating (even-numbered) years; however, stocking occurred in consecutive years from 2000 through 2002 to make up for sub-quota stocking in 2000. (Only 4,846 pounds of the 6,446- pound quota was stocked in 2000.) Because surplus production was available, 10,808 pounds of walleyes were stocked in 2001. Of 76 walleye sampled during 2003, only one fish was of an age when there was no stocking. This and results from previous surveys demonstrate that the lake’s walleye natural reproduction is very limited. The lower average gill net catch of 2003 likely reflects the lower, below-quota numbers of fish stocked in 2000. Walleye stocked in 2001 were not fully vulnerable to gill nets in 2003 because of these fishes’ smaller sizes (10.5-inch average) and use of different habitat than larger (adult) walleye. Among different areas of this 14,000-acre lake, the 2003 walleye gill catch net catch was highest in the Lower Lake (4.0/net), followed by that of the North and West Bays (3.3/net) and Upper Lake (2.3/net). Note: the biennial walleye fingerling stocking quota is split between 4,510 lb for Lower Lake and 1,936 lb for Upper Lake. Walleyes present in the North and West Bays are almost assuredly immigrants from other lake basins. Northern pike averaged 14.9/gill net, well above the lake-type median of 5.0/gill net. Since 1982, northern pike catches have never been lower than 8.0/gill net. 2003 northern pike averaged 21.4 inches and 2.4 pounds, with 19% of fish 25 inches or larger. Minnetonka’s northern pike population sustains itself via natural reproduction, and age determinations indicate reproduction has been consistently good. Although the abundant northern pike population creates the potential for good angler success, high numbers of northern pike can have some negative impacts, which include competition with walleye for forage fish (such as yellow perch) and predation on stocked walleye fingerlings. Yellow perch averaged 10.3 fish/gill net, a value below the lake-class median (17.1 fish/gill net). Recent perch catches have all been below the median, most likely because of predation from the abundant northern pike. Average perch size was 6.1 inches, and only 2% of the sample were 8 inches or larger. This size structure precludes most anglers from targeting yellow perch as a sport species, meaning that the species’ importance in Lake Minnetonka is primarily as forage. As mentioned earlier, largemouth bass are not sampled well with gill nets. Measurements from a 2001 bass-fishing tournament reflect presence of a quality largemouth bass population. Average length and weight of tournament-caught largemouth bass were, respectively, 15.8 inches and 2.3 pounds, with 16% of fish 18 inches or larger. .