Effects of turbidity on prey selection and foraging rate of hatchery-reared juvenile tiger muskellunge

Tiger muskellunge (northern pike Esox lucius × muskellunge E. masquinongy ) are stocked into aquatic systems across North America to control undesirable fish species or to create sportfishing opportunities. Because decreased water clarity can affect the poststocking foraging ability of an ambush predator like the tiger muskellunge, we evaluated the effects of turbidity on the foraging success of tiger muskellunge in a laboratory setting. We tested prey selectivity and total prey consumption by juvenile tiger muskellunge at four turbidity levels (Secchi depths of >84, 53, 26, and 18 cm) using three prey species: goldfish (Carassius auratus) (a surrogate for common carp Cyprinus carpio ), gizzard shad Dorosoma cepedianum , and green sunfish Lepomis cyanellus . Tiger muskellunge consumed significantly less prey at Secchi depths of 26 and 18 cm than at a Secchi depth of >84 or 53 cm. Selectivity for or against all prey types decreased as turbidity level increased, such that all the shad were positively selected and goldfish were negatively selected in clearer water. green sunfish were neutrally selected at all turbidity levels tested. These results suggest that increasing turbidity levels will negatively impact prey encounters and consumption rates, which likely will reduce growth rates of tiger muskellunge, ultimately reducing fish survival and stocking success.