Does Nest Site Selection and Habitat Affinity Mediate Egg Predation Risk for Sympatric Sunfishes?

The introduction of round goby (Neogobius melanostomus) into numerous freshwater systems in the Great Lakes region has prompted many studies to assess its impacts.  Some studies have implicated increased energy invested by guarding males and increased risk of egg predation among nesting fish species.  We were interested in comparing the goby egg predation effect, in addition to native egg predators, on sympatric centrarchids to test if nest site selection and habitat affinity influence their relative risk to nest predation. Five-minute observation trials were conducted to determine the identity and number of egg predators on 41 rock bass (Ambloplites rupestris) and 40 pumpkinseed (Lepomis gibbosus) nests, where guarding males were removed via angling. Habitat data was collected including depth, substrate, vegetation type, and vegetation coverage.  Rock bass had a higher egg predation rate (85.4 %) than pumpkinseed (45.0%), with nonnative predators accounting for 47.4% and 20.5% of the predators respectively.  Round goby and yellow perch were the dominant egg predators.  Other predators included pumpkinseed, bluegill (Lepomis macrochirus), juvenile Lepomis, rock bass, banded killifish (Fundulus diaphanous), and some unknown minnow species. Principle component analysis of habitat variables indicate that egg predation rate may be related to nest site selection and habitat affinity.