Evaluating the efficacy of nursery gear types for cultivating Atlantic surfclams (Spisula solidissima)

The Atlantic surfclam (Spisula solidissima) is a promising candidate for species diversification in the United States Northeast because it is native, grows rapidly, and is relatively recognizable to the public. However, gaps in the surfclam husbandry literature have left aquaculture practitioners without a complete understanding of how to best cultivate this species on commercial scales. In particular, relatively few studies have examined which culture conditions are necessary for rearing juvenile surfclams during the nursery phase. To fill this gap, controlled experiments were conducted to evaluate the efficacy of various gear types that are commonly used to rear other juvenile bivalve species. Specifically, growth and survival of early juvenile surfclams (0.4–2.7 mm) were compared when reared in different gear combinations, including downwellers, upwellers, and bell siphon systems. Similarly, growth and survival of late juvenile surfclams (1.1–18.0 mm) were compared when reared in upwellers and shallow raceways, with and without sand. Sediment accumulation, a proxy for culture cleanliness and system maintenance, was also monitored during the late nursery experiment. Results indicate that multiple rearing methods can effectively produce commercial-scale quantities of surfclams, but flow rate, food availability, and temperature are important factors that can limit gear efficiency. All early nursery gear systems performed similarly, while the late nursery upweller system performed significantly better than both types of shallow raceway systems. This study reinforces the feasibility of surfclams as a culture species that aligns well with the Northeast's established shellfish farming framework.