Population analysis of yellow perch, Perca flavescens (Mitchill), in Indiana waters of Lake Michigan

Yellow perch, Perca flavescens, were collected by trawling and gillnetting at 5m in a study area near Kintzele Ditch in Indiana waters of Lake Michigan. Sampling was conducted during the months of June, July and August in 1976 and 1977.Population characteristics were analyzed and compared to other studies. Growth rate and length-weight tended to be higher than in previous studies dealing with the Great Lakes, however, no specific reasons were identified. Growth differed between sexes, with females showing faster and more prolonged growth in older age fish. Significant overlap in ages I, II and III was apparent in both sexes, with growth differences evident between sexes of the same age. Virtually all (99%) age I male perch were mature, while only 15% age I females were mature. Approximately half of the age II females were mature with most age III females mature. Males were all mature at 150mm while females were all mature at 260mm.Sex ratios varied between samples, but were near unity for the combined sample period. No trends were apparent during the summer season for sex ratios in sex segregated populations.Catch-per-unit effort (CPE) remained relatively high during the entire sampling period. Lower CPE was noted with lower water temperatures. Sample variability was high throughout the sampling period, possibly due to gear selectivity, non-random distribution of individuals and repeated disturbances of the same area. When young-of-the-year were collected, their numbers were less variable than for older perch, a likely consequency of greater vulnerability to sample gear.The trawl tended to select for a wider range of sizes and greater total number of fish. The gill net consistently selected for larger fish. Neither method employed alone appeared capable of sampling the entire size range of fish.Differences in percent age in trawl and gill net samples were apparent with the gill net selecting for older fish. The trawl tended to sample a wide age range of fish.Comparison of data collected in Indiana and Michigan waters suggest fundamental differences in population structures. Indiana populations lacked significant numbers of larger, older fish which were adequately represented in samples from Michigan waters. Commercial harvest of perch in Indiana waters appears to be involved in the population structure differences.Ball State UniversityMuncie, IN 47306Thesis (M.S.)--Ball State University, 1981