Harvesting amphipods applying the integrated multitrophic aquaculture (IMTA) concept in off-shore areas

Abstract

Current trends in aquaculture research are towards more sustainable aquaculture, implementing more environment-friendly models such as integrated multi-trophic aquaculture (IMTA) systems. One possible IMTA strategy involves taking advantage of the species that naturally grow on aquaculture facility structures. Since amphipods have been cultured on a small and medium scale in laboratory conditions with the aim of using them as natural food for farmed fish or live prey for cephalopods, the high density of them in farm fouling could be pointing to a potential accessory culture, bringing new possibilities for commercial production and diversification of cultivable species. Two IMTA experiments focusing on harvesting amphipods were carried out between May and September 2014, testing two collector types, two depths, at 5 m and 15 m, and two experimental times. Extraction method selected to detach and recover the amphipods recovered more than 80% of the fauna gathered by the collectors, obtaining a final product with more than 86% purity in amphipods. Monthly production was estimated in 10 g wet-weight per collector (5 l volume) and it did not vary with the depth, indicating it is possible to use the entire water column occupied by the cages (down to 20 m depth) for this culture. This is the first pilot trial of an amphipod culture within an offshore IMTA facility. Nutrient uptake from wastes of the main culture was established, promoting a more sustainable development of aquaculture in the marine environment. Moreover, nutritional composition of the amphipod-based product is of great utility as a suitable natural ingredient in aquafeed compositions, and also as a potential food supplement for human nutrition.