Comparisons of Sex-Specific Growth and Weight–Length Relationships in Minnesota Black Crappie Populations

Abstract

We examined differences in sex-specific growth and weight–length relationships for five Minnesota populations of black crappies Pomoxis nigromaculatus. Male black crappies typically grew slightly faster than females, but observed differences in mean total lengths (TLs) at age were always 15 mm or less and were typically less than 10 mm. We detected few differences in log₁₀(weight)–log₁₀(TL) regressions between sexes, and predicted weights at 200 and 250 mm differed between sexes by less than 10 g. Our results indicate that biologists are justified in pooling sexes when estimating population metrics such as growth and condition because the minor differences in growth and weight–length relationships we observed would be unlikely to affect management decisions. Furthermore, while our evaluation did not specifically examine angler harvest selectivity, the small differences in growth and weight–length relationships observed between sexes seemed unlikely to promote sex-selective angler harvest within the lakes we examined. However, it remains possible that male growth advantages of more than 10 mm may promote selective removal of male fish in black crappie fisheries regulated by minimum length limits, where anglers may use the minimum length limit as a target when selecting fish for harvest and are more likely to measure individual fish.