There was a neat Research Article that was just shared by the Minnesota Muskie Alliance that we shared on our First Wisconsin Muskies Inc Facebook page. Here are the details of what has been released:
North American Journal of Fisheries Management
© 2020 American Fisheries Society ISSN: 0275-5947 print / 1548-8675 online DOI: 10.1002/nafm.10562
MANAGEMENT BRIEF: Are Muskellunge Affecting Fish Communities in Waters Where They Have Been Introduced? A Re-examination of Minnesota’s Stocked Muskellunge Waters
Michael L. Knapp*
Minnesota Department of Natural Resources, 1601 Minnesota Drive, Brainerd, Minnesota 56401, USA Steven W. Mero
Minnesota Department of Natural Resources, 1201 East Highway 2, Grand Rapids, Minnesota 55744, USA
David F. Staples
Minnesota Department of Natural Resources, 5463C West Broadway, Forest Lake, Minnesota 55025, USA
We’ve been waiting over 3 years for this study to get Peer Viewed and published. We’ve called it Knapp 2.0 and will get the paper up on the website as soon as we can. Here are the highlights.
The only outlier in the original Knapp study was the impact that Adult fish have over 15 years in the system. This addresses that.
CPUE= Catch Per Unit Effort. That’s signifies that they went out trying to catch fish in a net or electro fishing.
Northern Pike CPUE was significantly lower and mean weight significantly higher following Muskellunge introduction across all 36 lakes relative to the reference lakes.
Other significant changes included increases in Yellow Perch CPUE and declines in White Sucker CPUE across all 36 lakes after stocking compared to changes observed in the reference lakes
In the case of White Sucker CPUE, lakes in both study groups generally declined over the past 30years, but the stocked lakes showed evidence of a stronger decline associated with Muskellunge stocking.
Walleye CPUE and mean weight as well as CPUE for Cisco, Bluegill, and Black Crappie had no significant dif- ference following the introduction of Muskellunge relative to reference lakes
We observed a significant increase for Walleye CPUE in stocked lakes relative to the reference lakes when a 15-year gap was used.
While reference lakes mirrored the statewide decline in Yellow Perch CPUE (Bethke and Staples, 2015), it is noteworthy that Yellow Perch CPUE was significantly higher relative to reference lakes after Muskel lunge introduction even in lakes without Cisco, a scenario where potentially more predation may be directed towards Yellow Perch. It appears that Yellow Perch CPUE was influenced more by reduced predation from Northern Pike than direct predation by stocked Muskellunge.
Bluegill populations in Minnesota appear to be independent of Muskellunge management. Wolter et al. (2012) reported Bluegill as the primary prey for Muskellunge in the absence of soft-rayed prey but found no evidence that Muskellunge had any detrimental effect on Bluegill CPUE. Attempts to control Bluegill via stocking Muskellunge (Snow 1968) and hybrid Muskellunge (Storck and Newman 1992) have proven unsuccessful, which suggests that Muskellunge and Bluegill interactions are minimal.
Our study confirms the findings of Knapp et al. (2012), who found no changes in Black Crappie gill-net or trap-net CPUE for 41 stocked Muskellunge lakes. This is not unexpected, given that Muskellunge prefer soft-rayed fusiform prey, as noted earlier. However, our findings con- trast with Siler and Beyerle (1986), who observed a decline in Black Crappie trap-net catches, which they associated with a high-density
Muskellunge population. (MN manages Muskies in stocked lakes at very low population levels; as close to natural lakes as possible)
Our results indicate that trophy Muskellunge were present in the stocked lakes, and their presence has not adversely affected game fish populations in these waters, substantiating the conclusions of Knapp et al. (2012) while including 12 additional years of data and reference lakes. Our study was based on the Mississippi strain of Muskellunge stocked in Minnesota lakes, but results should be of interest to fisheries managers elsewhere because the study lakes represent a broad range of habitats, likely similar to many throughout the native and introduced range of Muskellunge.
We suggest that if Muskellunge in our study lakes were the predominant factor affecting other species in the fish community, we would expect to observe declines in relative abundance in the lakes without Cisco, particularly because we documented significantly lower White Sucker CPUE. Yet, we observed no
negative changes associated with the introduction of Muskellunge for the other study species. These observations imply that despite the ability of Muskellunge to attain great sizes, the densities present in this study are not sufficient to shape the fish communities through predation.
These data show that Muskellunge stocking has not had consistent negative effects on game fish populations in Minnesota, and for several metrics it was associated with beneficial changes.