Comparison of Electrofishing and Gill Nets for Sampling Cichlid Species

Introduced cichlid species are increasingly more common in tropical freshwater systems and expanding in range, often with negative consequences to receiving systems. To better understand, monitor, and manage these populations, investigators need improved cichlid sampling protocols. In this study, electrofishing and gill nets were compared for their effectiveness at collecting cichlid species during diel sampling in a Puerto Rico reservoir containing five cichlid species. Both gears were fished simultaneously during day and night periods in January and July. Species composition, species length frequencies, and overall cichlid catch per person-hour were compared. This study suggests that electrofishing, particularly at night, may be a more appropriate gear for sampling cichlid species in the littoral zone of reservoirs, as gill nets were more time intensive, had more variable catch rates, and exhibited considerable selectivity. Gill nets were highly selective for Red Devil Cichlid Amphilophus labiatus and Butterfly Peacock Bass Cichla ocellaris and were size-selective for Butterfly Peacock Bass. Electrofishing captured 37.7 cichlids/person-hour, compared with 13.7 cichlids/person-hour for gill nets. However, cichlid capture efficiency was low and variable, and therefore electrofishing catch rate should not be used as a measure of relative abundance. Received November 10, 2015; accepted April 20, 2016Published online August 19, 2016