Local Ecosystem Uptake of Stocked Trout by Cambarus bartonii and the Relevance of Prior Exposure to Stocking

Catherine M. Neville¹, Marissa L. Cubbage¹, Meaghen R. Stewart¹, Christopher J. Grant¹, and Norris Z. Muth^1,*

¹Juniata College, 1700 Moore Street, Huntingdon, PA 16652. *Corresponding author.

Northeastern Naturalist, Volume 27, Issue 1 (2020): 125–133

Abstract
We assessed variation in feeding preference of Cambarus bartonii (Appalachian Brook Crayfish) for stocked Salmo trutta (Brown Trout) or wild Salvelinus fontinalis (Brook Trout) across 8 central Pennsylvania headwater streams with different recent exposures to trout stocking. In separate trials, we allowed crayfish to interact with and choose between fillets of stocked Brown Trout or wild Brook Trout in either a flowing Y-apparatus or a standing-water aquarium. In the Y-apparatus trials and standing water aquarium trials, crayfish exhibited no detectable feeding preference based on proximity to stocking sites from which they were collected. In the Y-apparatus trials, crayfish were more likely to move towards a fillet type than not. Overall, our results provide evidence that crayfish do not distinguish between stocked Brown Trout and wild Brook Trout as food sources, and history of exposure to stocked trout does not influence feeding preference. Specifically, crayfish accept stocked trout as a food source, even if this resource is new to the environment (i.e., with the additions of new stocking sites in previously unstocked streams). Acceptance of stocked trout as a food resource suggests crayfish may play an important role in the local incorporation of this significant allochthonous nutrient input. Future research should address if local uptake of stocked trout by crayfish is able to mitigate downstream nutrient loads related to stocking.

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