Partial replacement of fishmeal in diets for turbot (Scophthalmus maximus, Linnaeus, 1758) culture using blue mussel (Mytilus edulis, Linneus, 1758) meat

The purpose of this study was to investigate whether meat from blue mussels (Mytilus edulis) harvested from offshore structures could be used as an alternative protein source in aquaculture fish feed for turbot (Scophthalmus maximus). Two feeding experiments with turbot were conducted in an initial experiment to test the applicability of mussel meal as a fishmeal replacement and/or supplement in turbot feed. In experiment A, the welfare, acceptance, and digestibility of feedstuff with 100%, 50% and 0% of mussel meal replacement for the fishmeal were tested for 8 weeks. In experiment B that followed, the convenience ratio of mussel meal protein in turbot feed for optimum growth was examined. Feedstuff with 25%, 10% and 0% of mussel meal were also fed for 8 (+6) weeks. Growth rates of fish were measured every 2 weeks and their health condition (liver somatic index) determined at the beginning and end of the experiments. Experiment A revealed that a replacement of fishmeal with either 100% or 50% mussel meal resulted in depressed growth (SGR: 1.31 ± 0.04 with 100% mussel meal; 1.54 ± 0.04 with 50% mussel meal; 1.71 ± 0.07 with 0% mussel meal). Experiment B revealed that a fishmeal replacement with 10% or 25% of mussel meal did not reduce growth nor did it have a negative effect on the health of the tested turbot. The study revealed that mussel meal has a high potential to serve as a supplement or as a fishmeal replacement in feed for turbot raised in aquaculture systems. Thus, its use in commercial aquaculture should be given future consideration.