Self-Recruitment in the Bumphead Parrotfish Under Different Levels of Fishing Pressure in the Solomon Islands
AdvisorsBerumen, Michael L.
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AbstractKnowledge in the spatial patterns of fish larval dispersal is crucial for the establishment of a sustainable management of fisheries and species conservation. Direct quantification of larval dispersal is a challenging task due to the difficulty associated with larval tracking in the vast ocean. However, genetic approaches can be used to estimate it. Here, I employed genetic markers (microsatellites) as a proxy to determine dispersal patterns and self-recruitment levels using parentage analysis in the bumphead parrotfish (Bolbometapon muricatum) in the Solomon Islands. Tissue samples of 3924 fish (1692 juveniles, 1121 males and 1111 females) were collected from a spear-fishery at the Kia District in Santa Isabel Island. The samples come from three distinct zones with different fishing pressure histories (lightly fished, recently fished, and heavily fished). The mean dispersal distance estimated for the bumphead parrotfish was 36.5 Km (range 4 – 78 Km) and the genetic diversity for the population studied was low in comparison with other reef fishes. The parentage analysis identified 68 parent–offspring relationships, which represents a self-recruitment level of almost 50 %. Most of the recruits were produced in the zone that recently started to be fished and most of these recruits dispersed to the heavily fished zone. Comparisons of genetic diversity and relatedness among adults and juveniles suggested the potential occurrence of sweepstakes reproductive success. These results suggest that management measures must be taken straightaway to assure the sustainability of the spear-fishery. These measures may imply the ban on juveniles fishing in the heavily fished zone and the larger adults in the recently fished zone. Overall, the population dynamics of the studied system seem to be strongly shaped by self-recruitment and sweepstakes reproduction events.