The Biology, Ecology and Future Conservation of Twaite Shad (Alosa fallax Lacépède), Allis Shad (Alosa alosa L.) and Killarney Shad (Alosa fallax killarnensis Tate Regan) in Ireland

Abstract:Anadromous twaite shad (Alosa fallax Lacépède) and allis shad (Alosa alosa L.) occur in Irish coastal waters, although only twaite shad has been confirmed to reproduce in Ireland. A landlocked subspecies of the twaite shad, known as the Killarney shad (Alosa fallax killarnensis), occurs in Lough Leane in south-western Ireland. Relatively little scientific research has been undertaken on the marine phases of these species in Ireland except for occasional reports of coastal bycatch. The growth, diet and parasite assemblages of twaite and allis shad sampled from Waterford Estuary and the upper tidal reaches of the River Barrow have been investigated since 1995. Similarly, aspects of the Killarney shad have been investigated since 1986. The number of gill rakers or general body size easily separates these subspecies of shad. The perceived threats to the twaite, Killarney and allis shad in Ireland, where they have been categorised as 'vulnerable' to extinction (twaite shad) and 'endangered' (Killarney and allis shad), are listed and discussed.