Project Examples

River Shannon Eel Management Programme

With partial funding from the ESB and in co-operation with the National University of Ireland, Galway, a major study on juvenile eels in the Shannon estuary and Lower Shannon and Shannon estuary was undertaken by Dr. William O’Connor of ECOFACT during the period 1995-2003. Inland Fisheries Ireland chose, for whatever reason, to not consider the current study or consult with its author during the preparation of Ireland’s Eel Management Plans. This major research project included the following detailed studies:-

an urgent best effort approach is needed now to maximise use of available glass eel and elver resources to save this species and restore its fisheries

Ardnacrusha hydroelectric station, River Shannon
Ardnacrusha hydroelectric station, River Shannon
  1. Immigration timing and activity rhythms of glass eel in the Shannon estuary in relation to temporal and environmental factors;
  2. Factors influencing the upstream riverine migration of juvenile eel on the River Shannon and selected tributaries of its estuary;
  3. Size structure and development stages of migrant eel populations, and the size selectivity of various trapping methods;
  4. Fish census results at the Ardnacrusha Borland fish-lift, with particular reference to eel Interactions of juvenile eel, brown trout Salmo trutta and other predators, in the tidal section of the lower Shannon River;
  5. The assessment of eel densities and population structures in the lower reaches of rivers in the Shannon estuary area using electrical fishing;
  6. Bycatch fish species recorded during the operation of a pilot scale glass eel fishery on the Shannon estuary

Download this entire study at this link: Biology and Management of European Eel  (Anguilla anguilla, L) in the Shannon Estuary, Ireland

The results of this study call into question the validity of many juvenile eel index sites in Ireland as it is clear that catch effort, and the quality of this effort, can have a highly significant influence on results obtained

During the study exceptional results were obtained in relation to catching glass eels and elvers with over 20 million juvenile eels captured. The key finding of the study was that despite the global downturn in eel numbers hugely significant catches of both glass eels and elvers could be made with determined and focused effort. Indeed, the annual catches made during the study period (1997-1999) exceeded the catches of any the previous catches since 1980, and (temporarily) reversed the decline in eel catches recorded on the River Shannon. The results of this study call into question the validity of many juvenile eel index sites in Ireland as it is clear that catch effort, and the quality of this effort, can have a highly significant influence on results obtained. It is also clear that an urgent best effort approach is needed now to maximise use of available glass eel and elver resources to save this species and restore its fisheries.

River Shannon elvers
River Shannon elvers

For further information please contact Dr. William O’Connor at +353 61 419477.

Also see our European Eel Research page on our main website www.ecofact.ie.