| Summary: | The European eel, Anauilla anauilla (L.) is widely distributed throughout European continental waters. However, there is much concern about the conservation status of the species and the long-term sustainable exploitation of stocks. Current European Commission (EC) International Council for the Exploration of the Seas (ICES) advice remains in place: ‘to reduce anthropogenic impacts (on A. anguilla) to as close to zero as possible’. In Northern Ireland A. anguilla are considered ubiquitous to many freshwater and brackish water habitats and are harvested commercially from the Lough Neagh / River Bann catchment. Through active stakeholder engagement and consultation - Lough Neagh Fishermans Cooperative Society (LNFCS) and the Agri-Food and Bioscience Institute (AFBI)-a number of key aims were identified, that formed the basis of this thesis. Specifically, we aimed to: 1. Establish the baseline biocontaminant levels (heavy metals, PCDDs, PCDFs and dioxin-like PCBs) in yellow phase eels. 2. Estimate fecundity, body condition and health parameters for silver phase eels migrating from Lough Neagh. 3. Assess the broader distribution of A. anguilla throughout catchments, not yet formally tested for the presence of the species. 4 Determine the prevalence of the swimbladder parasite. Anguillicola crassus and the where present, assess the ecological implications of infection on growth, fat content and body size. 4. Develop a combined approach using otolith Sr:Ca microchemistry and stable isotopes for estimating habitat residencv profiles in A. anguilla. 5. To characterise the physiology and ecology (age, growth, trophic position, body size, estimated fat content and lipid composition) of eels exhibiting different habitat residency profiles.
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