Physical and biochemical properties of particles released from an onshore Atlantic cod Gadus morhua aquaculture facility in the context of integrated multi-trophic aquaculture

摘要

To evaluate fish effluent as a food source for integrated multi-trophic aquaculture, particles released from an onshore aquaculture facility growing juvenile Atlantic cod (Gadus morhua) were collected. Particle distributions were determined with imageanalysis and a Coulter Multisizer, and samples were taken for dry weight, lipids and fatty acids. Effluent was filtered into three size fractions, <70 mum, 70-500 mum and >500 mum, which comprised 36%, 31% and 33% of the dry mass, respectively. Particlediameter varied from 0.1 mum to 2.4 mm, with the majority of particles in the 0.1 to 49 mum range. Particles <70 mum and >500 mum had settling rates of 0.02 mm/sec and 0.04 cm/sec, respectively, so the 36% of effluent available for mussel consumption isthat which has a greater potential to spread to surrounding areas. The top three lipid classes were free fatty acids (37-81%), phospholipids (4-21%) and triacylglycerols (6-15%). The essential fatty acids DHA and EPA, along with two zooplankton markers,were also present. Feeding experiments indicated mussels do ingest material in fish effluent.