Fine-Scale Population Structure and Mating System of Smallmouth Bass in Lake Opeongo

Smallmouth bass are an iteroparous nest-building species where territorial males provide parental care throughout the larval and early fry development stages. Large males are able to gain access to higher quality nesting habitat, defend larger territories, initiate nesting earlier in the spring, and extend the duration of parental care to later juvenile development stages. Males also show a high degree of nest site fidelity and are thought to exhibit natal philopatry. Smallmouth bass have elaborate courtship behavior, are sexually monomorphic, and are considered socially monogamous. Yet, little is still known about female reproductive ecology due to the limited amount of time spent in nesting areas during the spring spawning season. In this study, microsatellite genotype data for nearly 700 nest guarding males and over 6000 fry collected during the 2012 and 2013 breeding seasons were used to reconstruct the genotypes of breeding females. Genetic relatedness estimates for adult bass spawning in spatially proximate nesting locations were used to investigate the occurrence of sex-biased dispersal, inbreeding avoidance, inter-annual mate fidelity and mate selection, and the occurrence of extra-pair mating. This study represents one of the first attempts to assess the fine-scale population genetic structure and genetic mating system in this species.