Seasonal Distributions, Movements, and Habitat use of Adult Yellow Perch in a Simple Basin

Yellow perch Perca flavescens are an important sport and prey fish species in the glacial lakes region of eastern South Dakota. As a result, the biology of yellow perch throughout this region has been well documented. However, no studies have directly examined the movement patterns and habitat use of this species on a seasonal and daily basis. The objectives of my research were to 1) compare the distributions, movement rates, and habitat use of adult yellow perch among seasons, lengths groups, and sexes, 2) use telemetry data and associated habitat characteristics to develop a predictive model of yellow perch occurrence, and 3) compare prey density and composition, and perch stomach contents among predicted high and low probability sites. Ultrasonic telemetry was used to examine seasonal and diel movement patterns of two size groups (small = 219-235 mm TL, large = 250-270 mm TL) of adult yellow perch in Lake Madison, South Dakota from October 2004 through September 2005. At the beginning of each season (fall 2004, spring and summer 2005) 10 small and 10 large yellow perch were equipped with external acoustic transmitters. In the spring, when sex could be identified, similar numbers of males and females were equipped with transmitters. Transmitter-bearing yellow perch were located by boat with a hand-held directional hydrophone during morning, midday, or evening tracking periods, with each period represented at least four times per month. Additionally, 24-h tracking sessions, in which eight individuals were continuously located every 1 to 2 h, were completed once per month to examine movement rates within diel periods. Telemetry locations were overlaid onto lake maps and substrate coverages using ArcView 3.2 to determine seasonal and diel changes in distance from shore, depth at location, and substrate selection. Mean distance from shore varied throughout the study, ranging from 12.6 m to 874.0 m, with yellow perch farthest from shore during the summer (mean=343.9 m, SE=10.3) and closest to shore during the spring (mean=250.7 m, SE=10.9). Depths utilized by yellow perch ranged from 1.2 to 4.3 m, with perch located deepest during the summer (mean=3.4 m, SE=0.02) and shallowest during the fall (mean=2.9 m, SE=0.02). Both length groups displayed similar distributions throughout the year, while male and female distributions were similar during the spring. Tagged yellow perch were most active during the fall (mean=97.6 m/h, SE=8.9) and least active during the summer (mean=45.6 m/h, SE=4.0). Seasonal differences in activity corresponded to angler harvest rates, with the greatest percentage of tagged fish harvested during the fall (37%). Yellow perch did not exhibit crepuscular peaks in activity, with the highest movement rates observed during the day (mean=92.6 m/h, SE=6.6) and lowest recorded during the night (mean=27.6 m/h, SE=3.1). This diel activity cycle was consistent across seasons, sizes, and sexes. Substrate selection was minimal and was likely an artifact of the relatively homogeneous substrate composition of Lake Madison. Logistic regression was used develop a predictive model of yellow perch occurrence during the summer of 2006. Distance from shore, depth, and substrate were used as independent variables for the model to identify habitat characteristics related to yellow perch distributions (i.e., telemetry locations). The resulting model included depth as the only independent variable influencing the presence of yellow perch, with the probability of occurrence increasing as depth increased. Based on the results of the logistic model, areas with a predicted high probability (\u3e80%) and low probability (\u3c50%) of yellow perch occurrence were identified. Catch per unit effort (CPUE, number of yellow perch ≥200 mm / gill net / h) was compared between four predicted high use and four predicted low use sites. Stomachs were collected from all captured yellow perch to allow diet comparisons between predicted high and low use areas. Additionally, zooplankton, benthic invertebrates, and prey fish were sampled at each site. Yellow perch CPUE was higher in sites with predicted high probabilities of yellow perch occurrence (mean=2.7/hr, SE=1.1) than those with a predicted low probability (mean=0.8/hr, SE=0.2). However, due to one high probability net producing the overall lowest CPUE, the difference between high and low use areas was not significant. A total of 81 stomachs were collected for diet analysis, with 95.1% containing food items. Overall, macroinvertebrates were most abundant in yellow perch diets, with low numbers of zooplankton consumed, and only one prey fish observed. Yellow perch from high use sites consumed a greater diversity of prey items, including more Amphipoda, Corixidae, and Daphnia spp. compared to perch from low probability sites that consumed primarily Chironomidae. Prey abundance and composition were similar among predicted high and low use areas, and prey items from yellow perch stomachs were typically larger than those sampled in the environment. Modeling fish distributions based on habitat characteristics can be a useful application of telemetry data. The summer distribution of yellow perch in Lake Madison was predicted using a logistic model based on habitat characteristics. An offshore movement to deeper habitats during this season may be a common trend in simple basins and should be considered when designing sampling protocols to target yellow perch. In addition, yellow perch were located closest to shore during the spring, likely as a result of spawning activity. Hence, implementation of artificial spawning substrates (e.g., tree reefs) would be most frequently encountered, and therefore most effective, if placed in shallow littoral habitats. A fall creel survey would benefit managers responsible for monitoring the yellow perch population in Lake Madison, as the results from this study suggest that a substantial proportion of the total annual harvest may occur during this season