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

Abstract

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.