SUSPENSION CULTURE OF THE GREAT SCALLOP Pecten maximus IN GALICIA, NW SPAIN: INTERMEDIATE SECONDARY CULTURE FROM JUVENILES TO YOUNG ADULTS

A strategy for producing juvenile Pecten maximus to a suitable size for final culture (≈20–60 mm shell-height) within a year is suggested. Effects of stocking density, fouling on cages and shells, and handling frequency (every 1, 2, or 3 mo) on scallop growth and survival were investigated. Small juveniles (16.8 ± 3.0 mm) were initially stocked in August at densities of 24, 36, and 48 scallops quarter−1 (17% to 34% coverage), and 35.5 ± 5.1 mm scallops were restocked in January to 6, 12, 18, and 24 quarter−1 (18% to 73%). Survival was neither affected by stocking density nor handling, and was 98% the first period and from 93.2% to 96.9% between January and July. Shell-growth was mainly affected by stocking density and less affected by handling frequency. Growth slowed down during the winter months, and stocking density influenced growth during all seasons. Juveniles kept at the lowest densities obtained highest growth. Final mean shell-height was 54.8–67.2 mm and coverage 22% to 165%. Scallops handled monthly and bimonthly had significantly larger sizes than scallops handled every three months. Fouling on the cages increased with rising sea temperature, whereas high stocking density significantly reduced fouling on cages. Effective production during intermediate secondary culture in Galicia should include high initial stocking density in August, restocking to low density in January, and changes or cleaning of cages every second month.