Quantifying inter-population variability in yellow perch sexual size dimorphism

Abstract

Size-selective angler behavior or the implementation of length-based regulations may have implications in harvest-oriented yellow perch (Perca flavescens) fisheries where perch populations may display sexual size dimorphism (SSD), even though the occurrence of SSD remains poorly documented. Predicted and observed mean lengths-at-age were used to describe the occurrence of yellow perch SSD in populations from four states and one Canadian province. In addition, abiotic and biotic variables were used to predict the occurrence of SSD in yellow perch populations. Predicted mean lengths-at-age were significantly greater for female yellow perch after age 3 indicating female-biased SSD (higher female growth rates and greater maximum attainable lengths) occurred upon maturity. Using observed mean lengths-at-age, 85% of the study populations had at least 1 year class where females were significantly larger than males. Female-biased SSD was present in almost two-thirds of the individual observed mean length-at-age year class comparisons. SSD could not be reliably predicted using yellow perch population dynamics or lake morphometry. Although, yellow perch SSD was positively correlated with lake productivity, a low fit statistic suggests a poor predictive relationship. This study has demonstrated the prevalence of female-biased SSD in yellow perch populations. Because yellow perch anglers are size selective and harvest oriented, the occurrence of female-biased SSD in a perch population will likely result in female-biased exploitation and, therefore, we recommend natural resource agencies collect age and gender-specific data to identify the occurrence of SSD in perch populations.