Development of an Index of Year-Class Strength and Identification of Recruitment Bottlenecks for Yellow Perch in South Dakota and Nebraska Glacial Lakes

Year-class strength of many sport fishes, including Yellow Perch Perca flavescens, is often indexed as the relative abundance of age-0 individuals at various stages of development (e.g., larvae and juveniles).  However, these estimates occur prior to the first overwinter period, which has been recognized as a critical period for other teleost fishes, and may not accurately predict eventual year-class strength.  Using a combination of theoretical models and empirical data, we evaluated correlations between successive ontogenetic stages of individual cohorts of Yellow Perch to estimate the earliest point at which year-class strength could be indexed.  Strong positive correlations between larval Yellow Perch abundance and abundance of age-0 perch in the fall (r = 0.78; P < 0.001) suggest that larval abundance may be an accurate index of eventual year-class strength in the fall.  However, weak and nonsignificant correlations between the abundance of fall age-0 Yellow Perch and subsequent ontogenetic stages (i.e., age-1 and age-2) suggest that year-class strength may not be fixed until later life stages (i.e., after the first overwinter period).  If year-class strength is fixed following the first overwinter period, management agencies may need to adjust sampling schemes to capture fluctuations in year-class strength and accurately index recruitment.