Evaluation of the Ecological Compatibility of Butterfly Peacock Cichlids and Largemouth Bass in Puerto Rico Reservoirs

Abstract

Introduction of peacock cichlids Cichla spp. into tropical and subtropical systems where they can successfully overwinter and reproduce has been a common practice in fisheries management. We evaluated the compatibility of nonnative butterfly peacock cichlids Cichla ocellaris and largemouth bass Micropterus salmoides in Puerto Rico reservoirs using (1) controlled juvenile interaction experiments, (2) examination of hatching periodicity and diet overlap of juveniles in a reservoir environment, and (3) comparison of adult catch data from 10 Puerto Rico reservoirs. In the juvenile interaction experiments, butterfly peacock cichlid juveniles in ponds with largemouth bass had slower growth in length (P = 0.020) and weight (P = 0.003) and lower survival (P = 0.002) than in ponds with only butterfly peacock cichlids. In reservoirs, largemouth bass spawning typically occurred 2–3 months before butterfly peacock cichlid spawning, which resulted in substantial size differences between the juveniles of the two species. Butterfly peacock cichlids fed almost exclusively on threadfin shad Dorosoma petenense; the largemouth bass diet included threadfin shad but was much more diverse. Correlation coefficients were negative for comparisons of adult largemouth bass and butterfly peacock cichlid catch rates in the reservoirs sampled. Pooled catch data from all reservoirs showed a significant inverse relationship in relative abundance (P = 0.026). Catch rates from reservoirs with and without butterfly peacock cichlid populations indicated that largemouth bass densities were higher in single-predator systems (mean = 85.1/h) than in dual-predator systems (9.8/h).