Abstract

Overfishing is one of the primary threats to marine species. Leopard grouper (Mycteroperca rosacea) and Nassau grouper (Epinephelus striatus), two commercially important grouper species, possess numerous biological attributes that make them vulnerable to extinction – longevity, large body size, late sexual maturity and slow growth rates. In addition to this they form spatially and temporally predictable spawning aggregations, conspicuous groupings that are targeted by artisanal fisheries. Studies that investigate the population genetics of these commercially threatened species could provide important insight into demographics of populations, as well as elucidate the genetic consequences of overfishing. This study utilized samples of Leopard and Nassau grouper collected throughout their geographic ranges. Each sample was sequenced for three mitochondrial markers and genotyped for nine polymorphic microsatellite loci. Preliminary results suggest that Leopard grouper have undergone a population expansion in the Gulf of California, while Nassau grouper have undergone population decline in the Caribbean Sea. Both population growth and decline observed in these species might be a consequence of intense fishing pressure within the geographic ranges occupied by both groupers. Future work will further investigate genetic consequences of overfishing, as well as utilize approaches to investigate more fine scale fluctuations in effective population size (?) over time.