Habitat Associations of Fish Species and their Assemblages in the Tonawanda and Johnson Creek Watersheds of Northwestern New York State

Abstract

Stream fishes and their habitats were surveyed at 108 sampling sites to determine the status of the rare longear sunfish (Lepomis megalotis) and redfin shiner (Lythrurus umbratilis) in the Tonawanda (TCW) and Johnson Creek (JCW) watersheds of northwestern New York, May-September 2005. Of the >27,500 individuals captured and 70 fish species identified, most were cyprinids, followed by centrarchids, catostomids, and percids. Each watershed revealed cyclic patterns and substantial variation in the longitudinal profiles of habitat and fish assemblage variables, especially at sites with anthropogenic disturbances. Fish assemblagees were easily delineated longitudinally in the two watersheds using detrended correspondence analysis (DCA) but associating fish species and their assemblage variables (CPUE, fish richness, Simpson’s Diversity) with habitat variables was more challenging using canonical correspondence analysis (CCA: 62 associations, 27 species) and multiple linear regression (MLR: 80 associations, 47 species/33 assemblages) at 17 watershed and sub-watershed scales. In the more statistically rigorous MLR analyses, aquatic vegetation accounted for the greatest number of habitat associations (32%), followed by pool type, bank cover and substrate composition (16-17% each), suggesting that these habitat features may have been the most important to stream fishes in the study. In most cases, these finding were supported by the literature on stream fish ecology. Overall, fish species richness has remained relatively high and stable over time in both watersheds, even with ongoing localized disturbances occurring in the lower basins: NYS Barge (Erie) Canal, Batavia Dam (TCW) and Lyndonville Dam (JCW), as well as agricultural and suburban activities. New habitat associations were suggested for seven species. Findings from this study have already assisted with restoration efforts for the longear sunfish and may support future management of lesser known stream fishes in New York State.