Research

Minnetonka Muskie Stocking Study

Consistent Lake Minnetonka muskellunge (muskie) management began in 1974. Stocking plans since 1998 have been requests for 2,925 Leech Lake Brood-strain fingerlings (about 12" long) in odd-numbered years. Actual stocking has varied because of inconsistent fingerling availability. Make-up with larger, older fish and stocking in unplanned years has, however, provided regular additions of muskies.

Substitutions of year-old ("yearling") muskies for fingerlings, when necessary, have been based on a ratio of 1 yearling per 3 fingerlings, since yearlings are a year older and up to 10 inches larger than fingerlings. This recommended "replacement ratio" has not been backed up by studies or field evidence.

To test the validity of the 3:1 fingerling-to-yearling ratio, MN DNR, Twin Cities Chapter of Muskies, Inc., and Hugh C. Becker Foundation started a project to track survival and performance of fingerling and yearling muskie stocked into three Twin Cities-area lakes-- Minnetonka, White Bear, and Bald Eagle. Lake Minnetonka had 1,214 fingerlings and 372 yearlings stocked in 2009, 1,200 fingerlings : 88 yearlings stocked in 2011, and 1,200 fingerlings : 215 yearlings stocked in 2012. The two northeastern metro lakes were stocked in 2008, 2010, and 2011. Some of these fish were purchased with Becker Foundation funds.

MN DNR Fisheries has and will continue to monitor these fish during surveys and via public reports of tagged and/or fin-clipped muskies. As fish become larger, tagged muskies will be tracked by volunteers providing increased fishing effort. Results from DNR sampling, tag/clip reports, and targeted fishing will help determine which number-size combinations of stocked muskies yielded the best returns.

Lake Minnetonka provisional summary results— Nov. 1, 2009-Aug. 23, 2018:

• Tagged fish stocked in autumns of 2009, 2011, and 2012
• Total numbers of tagged fish stocked: 2,827 fingerlings / 667 yearlings* (4.2 : 1 ratio)
• 66 reports: 34 stocked as fingerlings, 32 stocked as yearlings* (1.06:1 ratio, compared with a 1:1 expected ratio)
• * In 2009, 33 two-year-old fish were tagged and stocked; these fish were considered “yearlings” for study purposes. Two reports of these older fish have been made.
• 2011 tagging was stopped partway through when too few yearlings were available. 108 tagged fingerlings had already been released, along with non-tagged (but fin-clipped) fish to fill the lake’s stocking quota.
• One fish caught twice: an 11.3-inch fingerling (stocked November 2009) was reported in August 2015 at 37.0 inches and in June 2017 at 39.0 inches. Catch locations were reasonably close together. During its second capture, the fish was missing its right gill cover, but reported as healthy.

Muskies stocked for the study have been marked with both internal PIT tags (readable with a specialized scanner) and external numbered tags. The outer "Floy" tags are yellow, about an inch long, and are located near the dorsal fin. If you catch a tagged muskie, please leave the tag in the fish but record the tag number and data related to lake, date, and fish size via the internet tag-report form (preferred), or relay the information to the West Metro Area Fisheries Office. You can also use the form to report catches of fin-clipped muskies.

Muskie Stocking Study: Internal/External Tagging and Release

Fish Community Responses to the Introduction of Muskellunge in Minnesota Lakes

We evaluated responses of seven fish species to muskellunge by comparing catch per unit effort (CPUE) before and after muskellunge were stocked in 41 Minnesota lakes composed of 12 lake classes. The species examined were: northern pike Esox lucius, walleye Sander vitreus, yellow perch Perca flavescens, bluegill Lepomis macrochirus, black crappie Pomoxis nigromaculatus, white sucker Catostomus commersoni, and tullibee Core- gonus artedi. We found no significant decreases in mean CPUE among the lakes for any spe- cies after muskellunge stocking, either for the stocked lakes as a whole or within lake classes. There was a significant increase in mean CPUE for bluegill over the entire group of lakes and within lake class 24, in addition to an increase in mean CPUE for black crappie sampled by gill nets in lake class 25. Nevertheless, there was large variability in the changes in CPUE among lakes, and several individual lakes had significant increases or decreases in mean CPUE for some species following muskellunge stocking. Because the selection of lakes for muskellunge introductions must follow established, biologically-based guidelines and thus cannot be chosen at random, it is not statistically valid to extend these conclusions to lakes not chosen in this manner. The lack of consistent negative changes in mean CPUE after stocking suggests these fish species have generally coexisted well with muskellunge in these lakes at the densities that have resulted from stocking.

PROPER MUSKIE/PIKE HOLDING TECHNIQUES TO AVOID HARMING FISH