The detemination of emamectin benzoate and its fate in the environment as a result of fish farming

The farming of Atlantic salmon (Salmo salar) is challenged by sea lice infestations. An effective way to treat farmed salmon is by in-feed treatments such as Slice®. A reliable HPLC method for the determination of emamectin (EB), the active ingredient of Slice®, and its desmethylamino metabolite (DES) in sediment, salmon flesh and skin, seawater, mussels tMytilus edulis) and seaweed (Palm aria palmatai was developed. The study of EB stability showed that under anaerobic conditions it was persistent in different sediments at 4 and 14 QC. Another study demonstrated that the growth of seaweed (Palmaria palmatai was not affected by the presence of EB and that it did not accumulate significantly in the seaweed. Analyses of samples from a working salmon farm showed that, three months post-treatment, EB was present, by mass in descending order, in the salmon flesh, skin, faeces, mucus and sea lice with concentrations in each matrix declining steadily over the period. It was unknown if sea lice were a significant sink for EB in the environment; however, results suggested that faeces were the main route for EB entering the environment. Analyses of sediment collected on two sites showed that EB and DES dispersed mainly to the area within 25 m of the fish cage edges, although concentrations depended on sampling location in relation to water currents. Maximum EB concentrations were recorded three months after treatment. Seven days after treatment, 6 % of the total EB input was present in the sediments within 25 m of the cage edge. Neither EB nor DES were detected in seawater, mussels, periwinkles, dogwhelks and seaweed samples collected from the walkway and the surrounding environment. This work suggests that EB is not significantly accumulated in matrices out with the target organism and the sediment. Key words: emamectin benzoate, desmethylamino metabolite, sea lice, salmon farm, sediment, seaweed, stability, dispersion, accumulation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo