Intra?Annual Variability of Common Carp and Bigmouth Buffalo Electrofishing Data in Shallow Lakes

Common Carp Cyprinus carpio and Bigmouth Buffalo Ictiobus cyprinellus are widespread across the Midwest, where they can achieve high population densities in shallow lakes. Despite their contrasting statuses as invasive native fishes, these species commonly managed together due to capacity have deleterious effects on water quality. However, intra-annual sampling variability is poorly understood for both species, making it difficult track changes. We compared boat electrofishing CPUE proportional size distribution (PSD) of during May–October 2018–2020 seven northwestern Iowa also estimated effort necessary reach targets fish captured (100) precision (relative standard error < 25%) detect 25% 50% differences between samples. peaked June (29 fish/h), declined summer, was lowest October (9 fish/h). exhibited bimodal peaks May (16 fish/h) (12 with low catches August (2 structure largest (PSD preferred-size [PSD-P] = 92) smallest July (PSD-P 58). smaller 20) than all other months 34). Our number were typically reached within twenty-five 15-min transects periods catch rates but not after 100 most cases. results suggest that timing important reliably efficiently assessing populations. recommend Midwestern lakes maximize while minimizing influence seasonal variability.