Optimizing Cultured Mussel Yields: Second-Set Dynamics and Avoidance Strategies

摘要

Amajor production constraint for some mussel farms is an accumulation of unwanted mussel seed, known as second-set, on growout socks. Second-set reduces harvest yields and increases processing costs. The objectives of this study were 1) to examine mussel seed behaviour under varying environmental conditions, 2) to identify the biotic and abiotic factors involved in second-set dynamics, and 3) to determine the influence of socking depth (4 m, 9 m), deployment time (spring, autumn) and initial sockingdensity (-100, 200, 250, 300+ mussels per 30 cm) on mussel sock performance, The results indicate that mussel seed mobility is greatly influenced by seed size but to a lesser extent by food availability or temperature. Mussel settlement was heaviest during August. There was evidence of byssal drifting in the spring which may be a source of second-set. Reduced second set occurred at 9 m compared to 4 m, for all deployments times (ANOVA, P<0.001). High initial sock density (>300 mussels / 30 cm) resultedin less accumulation of second-set, regardless of depth, Husbandry practices were shown to influence second-set accumulation to a large extent. We conclude that second-set can be significantly reduced or avoided by a thorough understanding of site environmental and biological conditions with appropriate adjustments to husbandry practices.