Forecasting Abundance of Quality-Size Yellow Perch in Indiana Waters of Lake Michigan

Abstract
Because the yellow perch Perca flavescens is a valuable sport and commercial species in southern Lake Michigan, forecasts for abundance of quality-size fish would be beneficial. We analyzed a time series of annual index trawl catch per unit effort (CPUE) in order to identify a model that could be used in forecasting. Relative abundance of stock-size (≥130 mm) and quality-size (≥200 mm) fish in Indiana waters of Lake Michigan varied by about two orders of magnitude from 1975 to 1996 and declined to a low level during the 1990s. Cross-correlation was used to identify a strong positive relation between CPUE of stock-size fish (S) in year t and quality-size fish (Q) in year t + 2. This relation was described by the linear model, √Q t+2 = 2.68 + 0.00572·S t , and was due to survival and growth of sub-quality–stock-size fish from t to t + 2. The CPUE of quality fish predicted by the model closely approximated the trend in observed values. The model predicted that relative abundance of quality-size yell...