Identifying the biotic and abiotic factors influencing individual reproductive fitness under natural conditions is essential for understanding important aspects of a species’ evolutionary biology and
ecology, population dynamics, and life-history evolution. A reconstructed molecular pedigree for
adult smallmouth bass spawning in Lake Opeongo was used to characterize the genetic mating
system and mate selection, examine the extent of natal philopatry and the strength and direction
of sex-bias dispersal, and assess the inter-annual variance in reproductive success in a large,
heterogeneous natural system. A high reproductive skew among breeding adults was observed
with the majority of offspring being produced by a relatively small number of spawning adults.
The difference in reproductive success among adults was shown to be strongly influenced by
summer water temperature, male body size, and, to a lesser extent, fetch. These findings provide
key insights into this species reproductive ecology that will improve our ability to understand
and predict how populations will likely respond to various biotic and abiotic stressors,
management and conservation actions, and climate change.