Comparing growth of ear-hanging and lantern net cultured Atlantic sea scallops, Placopecten magellanicus, over a complete grow-out cycle to determine optimal harvest timing

Scallop aquaculture is a rapidly expanding global shellfish industry with high market value and consumer demand. However, growth in the aquaculture industry for the Atlantic sea scallop ( Placopecten magellanicus ) in North America has been uneven. Uncertainty in grow-out dynamics across the potential product portfolio make it difficult to establish robust business plans and bioeconomic benchmarks. Most Atlantic sea scallop aquaculture growth studies have focused on a whole scallop market, with a harvest target at a shell height of ~90 mm. Meanwhile, growth studies exceeding 100 mm, where scallops would enter the established adductor muscle market, are far less common because they require a product cycle of greater than three years under well-characterized conditions. In this study, shell height measurements were collected every three months using two husbandry methods, ear-hanging and lantern net suspended culture, over a four-year product cycle. Adductor muscle weight was tracked for the final year of grow-out, when an adductor muscle product would be economically feasible to sell. At the conclusion of the study, measurements for both husbandry methods exceeded 115 mm shell height and 37 g adductor muscle weight. While shell height differences between ear-hanging and lantern net cultures were relatively small (1.19–4.22 %) depending on temperature, the exponential relationship between shell height and adductor muscle weight resulted in a 10.9 % increase for ear-hanging over lantern net scallops harvested in August at approximately three years old (i.e. , > 90 mm). Adductor muscle weight differences between grow-out techniques indicate that ear-hanging could provide a more profitable option for aquaculture growers looking to improve production capacity, particularly if the risks of a longer production cycle can be mitigated. • Atlantic sea scallop aquaculture in the Gulf of Maine has the potential to reduce import market demand for scallop products in the United States. • We observed a ~ 4–12 % increased adductor muscle weight for ear-hanging compared to lantern net cultured sea scallops. • We recommend that growers culturing sea scallops for adductor muscle markets consider ear-hanging, while whole scallop market growers could consider both grow-out options.