Ecological Considerations in Muskellunge Introductions – Exploring Effects on Resident Fish Populations

Consideration of ecological factors that influence muskellunge stocking success including predation by resident species, rearing techniques, source populations, and appropriate prey bases of receiving waters have allowed for specific recommendations that have improved survival of stocked fish and successful development of new muskellunge fisheries.  As the ability of managers to establish muskellunge outside of their native range has improved there is a need to refine considerations concerning interactions between introduced muskellunge and both non-game and recreationally important resident species.  More recently, we have been examining the interaction between introduced muskellunge and resident fish populations with specific focus on recreationally important species including largemouth bass and bluegill sunfish.  At the scale of whole lakes, largemouth bass relative abundance (measured as CPUE) increased after muskellunge introduction across seven of eight lakes examined.  A series of controlled experiments across a range of spatial scales has found a facilitative interaction between introduced muskellunge and resident largemouth bass with an emergent multiple predator effect.  Populations of largemouth bass responded positively to the presence of juvenile muskellunge in a replicated pond study exhibiting increased growth in concert with increased mortality of bluegill sunfish prey.  Effects of introduced muskellunge on bluegill populations at the field scale were not consistent with laboratory and pond studies suggesting that the availability of alternative prey (gizzard shad and cyprinids) for muskellunge may buffer this species from effects of muskellunge predation.  These results highlight the importance of evaluating species introductions within an ecological context that integrates the relative importance of limiting factors such as predation, stocking strategies, and abiotic factors with the potential consequences of establishing new species on the recipient aquatic community.