Knowledge of the quantitative and qualitative properties of salmonid faeces is necessary for aquaculture waste dispersal models, and the design of integrated multi-trophic aquaculture (IMTA) systems. The amount and proximate composition of salmonid faeces can be estimated using a mass-balance, nutritional approach. Indigestible components of salmonid diets have the potential to a¡ect faecal'cohesiveness'or 'stability' . Nutrient content and density of faeces can vary depending on diet and submersion time. Faecal density has a greater in£uence on settling velocity than faecal size. Published settling velocity data on salmonid faeces are highly variable due to di¡erences in ¢sh size, rearing systems, collection time, water density, methodology, the mass fraction tested and diet. Most faecal settling data used in published salmonid waste dispersal models are rudimentary and recent information suggests that such models are highly sensitive to this input. The design of open-water IMTA systems and estimation of nutrient capture and recovery from co-cultured ¢lter feeders is di⁄cult due to limited information on particle size, digestibility, settleable and non-settleable mass fractions of salmonid faeces at cage environments. Implications of faecal properties on the accountability for the e¡ects of aquaculture nutrient loading are discussed.

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Population management of Lepeophtheirus salmonis in Canada currently relies on chemotherapeutants to remove attached stages of the ectoparasite. However, some populations of L. salmonis are developing resistance to chemotherapeutants making alternate management measures necessary. This article explores the ability of filter-feeding shellfish [i.e. blue mussels (Mytilus edulis) and Atlantic sea scallops (Placopecten magellanicus)] to consume the copepodid stages of L. salmonis in the laboratory under static and flowing water conditions, with variable copepodid densities, and with the aid of a light attractant. Mytilus edulis consumed copepodids under both static and flowing water conditions, and the proportion of individuals ingested was similar at low and high copepodid densities, suggesting that M. edulis was not saturated at the concentrations tested. Also, M. edulis consumed more copepodids when a light attractant was present, suggesting that lights may be useful to concentrate widely dispersed copepodids around cultured shellfish in the field. Finally, P. magellanicus consumed the same number of copepodids as an equivalent total wet weight of M. edulis. During each of the four separate experiments, shellfish consumed between 18 and 38% of the copepodids presented per hour, suggesting that both species are well suited for low level removal of copepodids over time.