Comparative Vulnerability of Three Esocids to Largemouth Bass (Micropterus salmoides) predation

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Abstract
We compared vulnerability among tiger muskellunge (Esox masquinongy .times. E. lucius) (TM), northern pike (E. lucius) (NP), and muskellunge (E. masquinongy) (M) to predation by largemouth bass (Micropterus salmoides). Equal numbers (about 25/ha) and sizes (either 145, 180, or 205 mm) of each esocid taxa were stocked into three reservoirs (40-89 ha) during 3 yr (five stockings total). Tiger muskellunge were significantly more susceptible to predation (.hivin.x = 30%, range 1-53% mortality) than muskellunge (.hivin.x = 12%, range 2-26%); northern pike were intermediate in susceptibility (.hivin.x = 19%, range 2-35%). Esocid size influenced predation rates for all taxa; losses to predation by largemouth bass decreased from an average of 31% at 145 mm to 2% at 205 mm. Pond experiments (N = 7) provided results similar to reservoirs: TM > NP > M. In laboratory pools with simulated vegetation (N = 106 experiments), susceptibility to predation among esocids did not differ. Dispersal rates by esocids were similar in reservoirs and all taxa preferred vegetated habitats. However, differential habitat selection may partially explain why tiger muskellunge are more vulnerable to largemouth bass predation, as they spent more time in open than vegatated habitats in both pond and pool experiments than either of the parent species. For all taxa, stocking lengths .gtoreq.205 mm in fall will increase survival by reducing predatory losses.