sustain the recruitment of oyster spat as an essential food. An oyster spat survey can help give the Natural Resources Group a better idea of where an ideal oyster restoration location may be on the Bronx River. choctawhatcheeana was abundantly detected in the digestive tract of oyster larvae collected in the field, suggesting that Cyclotella spp. The separation in the recruitment peak between the oyster and the barnacle indicated that August was the most favorable window for capturing oyster spat through substratum addition to the water around the natural reef. To derive ranks, the mean oyster density per shell on each plot was measured, and the average recruitment density for each plot was calculated. The tidal gradient was divided into 3 zones within which recruitment plots were ranked by oyster spat density, corrected to per cm 2 of available shell surface area. in sea water led to a successful larval settlement in both 20. The inshore sites (SH1 and SH2) with high oyster recruitment and low barnacle recruitment should be recognized as the natural spatfall sites for the natural oyster reef restoration. For Experiment 1, a non-parametric statistical approach was used. The results of metabarcoding analysis indicated that increase in <10 μm size diatom Cyclotella spp. We also examined the species composition of 26.9 ☌ and chlorophyll a concentrations for 5 μg L −1. In order to elucidate the favorable environmental window for oyster spat collection, we investigated water quality parameters (water temperature, salinity and nutrients), abundance of larval food and success of larval settlement during the period of spat collection in Hiroshima Bay. Rafted aquaculture using natural spat of the native oyster is conducted in this bay and spat collection during the spawning season in summer is a key process for sustainable farming. The data generated will identify sites with high recruitment rates, where future spat collection activities can be focused, and sites where recruitment is low, that do not justify further spat collection activity. Improved oyster production, using spat collectors only, should deploy collectors during Fiji’s warmer summer season for a 14-month duration.Hiroshima Bay, located in the western part of the Seto Inland Sea, is the largest Pacific oyster Crassostrea gigas farming area in Japan. The aim of this study was to determine recruitment of pearl oysters at 29 sites across the Fiji Islands using standard spat collection methods already used in Fiji. 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. 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. 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. Harvested oysters grown in panel nets during intermediate culture increased significantly in size and weight with 100 % survival. Worldwide oyster population declines have been dramatic and efforts to restore declining populations and the services they provide are ongoing.
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). Oysters provide habitat, sediment stabilization, and improved water quality, and are important foundation species in many estuarine ecosystems. 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. 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. 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. 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. Fiji’s cultured pearl sector relies on wild collected oysters ( Pinctada margaritifera) for culture stock.
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