For muskellunge anglers stocking this prized quarry may or may not be a familiar concept, depending on where you live. In my home state of Illinois, for example, our waters are maintained solely by stocking; there is little to no natural reproduction. For states like Wisconsin and Minnesota, stocking may be conducted on some, perhaps most, but not all lakes because some can be sustained through natural reproduction. As muskellunge angling has increased in popularity, the call to stock additional waters and current waters with more fish has risen greatly.
Muskellunge stocking in Wisconsin is commonplace and supported widely by anglers throughout the state, particularly in the more southern waters where natural reproduction has little influence on populations. One large problem exists with widespread stocking: genetic conservation. In other words, it is imperative to keep certain molecular components (i.e., alleles) within a population of muskellunge that will allow them to survive and thrive. Although this seems like it would be easy to do, not all fish from one lake react in the same way to conditions other lakes present. Some fish have rare genetics/alleles that allow them to survive in a given environment(s).
Hatchery programs often involve only a few individuals to supply vast numbers of fingerlings for stocking. When only a few individuals are used, the likelihood of extirpating rare alleles increases and muskellunge may lose the ability to naturally reproduce in the wild. This phenomenon is known as outbreeding depression.
One of the first issues researchers faced was figuring out where to take the adult individuals (i.e., broodstock) for Wisconsin's stocking program. Researchers identified broodstock as needing to have the ability to grow, mature, and reproduce in their present habitats. Another potential problem arises when choosing which bodies of water to take broodstock from because, in Wisconsin, some waters are either maintained solely by stocking, supplementally stocked, or not stocked at all. The latter water bodies are ideal as adults and offspring alike have not undergone artificial selection against various heritable traits (e.g., some behavioral traits). Researchers further identified lakes greater than 1,000 acres as appropriate for the stocking programs, and water bodies should be used on a rotating basis rather than only focusing on one. In addition, the minimum number of broodstock to be taken must be considered because if too few individuals are used then genetic diversity decreases. A higher number is better and researchers suggest a minimum 50 breeders to be used, with a target of at least 20 females bred with 3 males being ideal.
One issue that adds complications to conserving genetics within the bounds of a stocking program, is the needs of the angling public. More specifically, anglers want fast growth rates and big fish. However, in order to fulfill the objectives of a hatchery-based conservation program it is necessary to represent a wide variety of traits that mimic natural populations. Certainly, hatchery operations should include large fish, but should not be limited to the largest individuals.
Jennings et al. have provided researchers with excellent guidelines to improve hatchery operations. Although it may be difficult to swallow, stocking isn't or shouldn't be about only producing the biggest fish possible. Selecting only the biggest fish to be stocked could pose serious problems for the future of a fishery if important alleles are eliminated from the genetic pool. Instead, the goal should be to produce a population that can thrive and survive for many years to come (and still kick out big fish!). The future looks bright for muskellunge stocking programs, and an added benefit of this article is that the contents provide a set of guidelines for hatchery programs of other fish species to utilize for enhancing their fisheries.
Article reference: Jennings, M.J., Sloss, B.L., Hatzenbeler, G.R., Kampa, J.M., Simonson, T.D., Avelallemant, S.P., Lindenberger, G.A., and Underwood, B.D. 2010. Implementation of genetic conservation practices in a muskellunge propagation and stocking program. Fisheries 35, 388-395.
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