Studies of the Eel Anguila Anguila in Ireland No. 4. In the Munster Blackwater River

Abstract

Yellow eels from estuarine and freshwater populations were sampled by fyke netting: in 1965 and 1966 2,221 specimens from the estuary and in 1972 and 1973 826 specimens from freshwater. It was the first extensive study of eels in an Irish river and the population was found to be more dense than that recorded in lakes. Growth in the estuary was relatively fast and spawning migration began at 9 years while in the freshwater growth was slower and migration began about four years later. One specimen of 36 years old was found and more than 17% of the freshwater sample were over 19 years. Eels of less than 40 cm fed largely on invertebrates whereas eels of 50 cm and over fed mainly on fish, cyprinids being taken to a much greater degree than salmonids. It was calculated that fyke netting of the unexploited fishery could yield a catch of 21 tonne of eels of over 50 em length in the lowland freshwater portion of the river.