Advisor: Brian Sloss
Identification of contemporary muskellunge genetic stock structure throughout northern Wisconsin
Muskellunge
(Esox masquinongy) are a prized sportfish throughout their native range.
Wisconsin contains >700 muskellunge populations providing a diverse
array of angling experiences from high-density action waters to
low-density trophy fisheries. The Wisconsin Department of Natural
Resources’ (WDNR) muskellunge management goals include maximizing
angling opportunities while preserving genetic integrity. Historically,
the WDNR has managed musky populations through regulations, such as
daily bag limits and length limits, and a prolific stocking program.
However, supplemental muskellunge stocking can have strong impacts on
the genetic integrity of a population. The use of stocks when managing
native populations minimizes risks to genetic integrity including
outbreeding depression and introgression. Currently, the WDNR delineates
genetic management units based on watershed boundaries and genetic data.
The available genetic data showed
low variation and little genetic structure resulting in a more-or-less
default watershed delineation. To develop a more precise management
approach, we used microsatellite genotyping and non-lethal sampling to
identify genetic structure among naturally recruiting muskellunge
populations in Wisconsin. The WDNR provided non-lethal fin clips from 38
naturally recruiting populations (n ≈ 50/population) across the native
range of muskellunge in Wisconsin. Microsatellite genotyping was
conducted using a suite of 14 loci developed in our lab. Resulting
genotypes were analyzed using a genetic stock identification technique
which showed an east-west split among populations not stocked since
1990. Two contemporary management units, the upper Chippewa River and
the Lake Superior, failed to resolve suggesting historical genetic
boundaries and contemporary watershed boundaries are not congruent for
these two units. Further delineation and resolution of stock boundaries
within the state will provide for more accurate and efficient management
of Wisconsin’s muskellunge resource.