Evidence of reduced reproductive success of nesting largemouth bass sampled with standard electrofishing procedures

Fisheries biologists commonly use electrofishing as a fish collection technique. Because electrofishing is often conducted in the spring, it has the potential to negatively affect the reproductive activities of largemouth bass Micropterus satmoides, particularly the parental care activities of the nest-guarding males. To assess the effect of electrofishing on nest-guarding activities, we electrofished parental males from their nests in an Illinois lake, held them in a tank for 30 min, and released them 0.25 km from their nest sites-as would be done during routine surveys. We then assessed the presence or absence of broods and males on their nests 24 h later to determine rates of abandonment. Electrofished males had greater levels of nest abandonment (41%; N = 34) than did control males (9.5%; N = 42). The developmental stage of the offspring present in the nest during the electrofishing, however, did not influence abandonment rate. These results suggest that springtime electrofishing can negatively affect the reproductive success of individual largemouth bass and thus may have implications for recruitment.