Aquaculture Reports (Oct 2022)
Optimizing community-based pearl oyster (Pinctada margaritifera) spat collection strategies in the Fiji Islands
Abstract
Fiji’s cultured pearl sector relies on wild collected oysters (Pinctada margaritifera) for culture stock. Most oysters are collected by community-based spat collection enterprises but there is little information on the optimal duration of spat collector deployment, which potentially affects oyster yield, oyster size, and the sales value of resulting oysters. We investigated the influence of the timing and duration of spat collector deployment on these parameters, and the potential for early removal of juveniles from spat collectors for intermediate culture. Spat collectors deployed in October and January, during Fiji’s warmer summer season, generated higher numbers of oysters than those deployed in the cooler winter season. The average numbers of spat harvested from spat collectors deployed for 6-month, 8-month, and 14-month periods were 0.6, 1.8, and 1.7 spat per collector, respectively. Shorter spat collector deployment duration of 8-months generated similar numbers of oysters to those of 14-months; however, oysters harvested after 8-months were smaller (20.4 ± 1.8 g) than those harvested after 14-months (89.2 ± 3.2 g). Harvested oysters grown in panel nets during intermediate culture increased significantly in size and weight with 100 % survival. However, oysters removed from spat collectors after 8-months and grown in panel nets for a further 6-months were smaller than those retained on spat collectors for the same 14-month period. Results indicate that, of the options tested, the most profitable for pearl oyster spat collection in Fiji is to harvest spat collectors after 14-months then grow oysters in panel nets for a further 6-months. This assessment is based on production estimates only and detailed cost-benefit analysis is recommended to account for the additional equipment costs and labour inputs required after spat collector harvest. Improved oyster production, using spat collectors only, should deploy collectors during Fiji’s warmer summer season for a 14-month duration.
