Comparative performance of hatchery-reared and wild Scylla paramamosain (Estampador, 1949) in pond culture

Abstract

The performance of hatchery-reared juveniles either in aquaculture grow-out systems or stock enhancement is likely to be dependent on a range of factors during the hatchery phase of production. With recent progress in the development of hatchery systems for the mud crabs Scylla spp., there is growing interest in evaluation of the quality of hatchery-reared juveniles relative to wild seed crabs as currently used in aquaculture. Hatchery-reared and wild-collected Scylla paramamosain juveniles were stocked either together in ponds or separately. All crabs were tagged with microwire-coded tags, so that origin could be determined in the mixed groups. Preliminary validation demonstrated that tagging did not affect survival or growth, with a tag retention of 94%. After 106 days of culture, there was no significant difference in survival at harvest between the two sources of crabs. The wild juvenile crabs had a significantly higher initial weight:carapace width (CW) ratio compared with those from the hatchery, indicating a difference in condition. However, where crabs were stocked separately, the hatchery-reared animals exhibited significantly faster growth than those collected from the wild, both in terms of specific growth rate and CW increase per month. However, in the mixed ponds, where there was competition with wild crabs, there was no significant difference in growth rate between crabs from the two sources. Overall, the results demonstrate that the growth performance of hatchery-reared S. paramamosain can at least equal that of wild-collected seed crabs in ponds culture.