Nursery growth, survival and chemical composition of great scallop Pecten maximus (L.) spat from different larval settlement groups

Abstract

Scallop Pecten maximus spat (1.3–2.1 mm shell height) from different settlement groups were transferred from hatchery to land-based nursery at different ages and sizes. Chemical content, growth and survival were compared at transfer time and after 1 and 8 weeks of nursery growth. Growth was lowest and mortality highest in the first week after transfer. Mean shell height growth was 21.5–71.4 μm day−1 and ash-free dry weight (AFDW) growth −2.7 to 10.3 μg day−1. Spat from the first settlement group attained a larger size and weight than spat from larvae settled 3 days later, but had a lower daily growth rate (%). Keeping the late-settled spat a longer time in the hatchery to reach a bigger size before transfer seemed not to improve subsequent nursery growth. Survival showed a large variation with mean survival ranging from 32% to 74%. A substantial reduction in lipid content was found after transfer to the nursery. Sterol content at transfer was the only lipid class correlating with survival in the nursery. Based on the results, it is justified that spat groups of different settlement age are included in production of 15-mm great scallop spat if they are transferred from the hatchery at the same age.