Eels (anguilla Anguilla (l.)) of the Lower River Shannon, with Particular Reference to Seasonality in Their Activity and Feeding Ecology

The general biology and seasonal ecology of eels from a riffle section of the lower reaches of Ireland’s largest river system, the River Shannon, were investigated. Eels at this location occurred in high densities, had a slow growth rate and were predominantly male at maturation. Although they fed to some degree all year round, foraging activity of the eels was highest in the months of May to September, inclusive. Their diet, which was dominated by larval Ephemeroptera and Trichoptera, reflected the typical composition of the macroinvertebrate species assemblage of the riffle habitat sampled. Little evidence of piscivory or of the potential impact of the high density eel population on the salmonid stocks of this river section was recorded.