Multiple paternity assessment and paternity assignment in wild european lobster (Homarus gammarus) : comparing a no-take reserve and an exploited area

Understanding the mechanisms driving mating systems is intricate for wild populations of species where behavioral observations are difficult, but nonetheless imperative for harvested species. This study investigated the occurrence and frequency of multiple paternity for the European lobster (Homarus gammarus) in a marine reserve (MPA) and in a heavily exploited control area on the Norwegian Skagerrak coast. Also, this study is the first to conduct a parental assignment in a wild lobster population. With three to six microsatellite loci genotyped, 81 females and ten offspring from each brood, high level of multiple paternity was discovered in both reserve (27 and 96%) and control area (3 and 90%) with no significances in regards to body size. However, significantly more cases of multiple paternity was observed in the reserve area using the most parsimonious estimate. These results demonstrate that females in all size categories may mate with more than one male after pre-molt insemination, perhaps due to altered mating behavior as result of decades of overharvest or due to high density of individuals. Of the 475 candidate males genotyped for six loci, 13 of them were assigned to offspring of 14 females but with no clear patterns for assortative mating, although 71% of the pairs consisted of a male bigger than the female. As five of the mated pairs have crossed the boundaries of the reserve in either direction there are tendencies of spill-over effects. However, eight of the pairs resided in the marine reserve which also indicating a high site fidelity. Further research to unveil the genetically significance of multiple paternity and what drives the females’ choice is important for management of this high valued species.