Understanding what we cannot see: a genetic approach to the mating system of the Southern Lanternshark, Etmopterus granulosus

Abstract

The Southern Lanternshark, Etmopterus granulosus, is a deep-sea shark commonly found throughout the oceans of the southern hemisphere and frequently caught as bycatch in deep-sea fisheries. Despite its common occurrence, little is known about this species’ life history and reproductive biology. Here, we develop species-specific microsatellite markers to better understand the mating system of E. granulosus. Eighteen litters were opportunistically collected as bycatch along the Madagascar Ridge, Walter’s Shoal, and Southern Indian Ocean Ridge. Novel microsatellite loci were used to test for the presence and frequency of multiple paternity and morphological data were obtained from mothers to examine whether litter size or polyandry correlated with female size. Multiple paternity was found in 33% of litters, but no significant relationship between either litter size or the occurrence of polyandry and female size was found, although some adult individuals were found to have high internal relatedness. The frequency of multiple paternity in conjunction with these other factors could be indicators of mating between relatives or a reduction in population size due to fishing pressure.