Feeding habits and condition of two landlocked populations of allis shad (Alosa alosa) in Portugal

Abstract

Only three cases of landlocked populations of allis shad (Alosa alosa L) were reported until the present, being two of them in Portugal. In this paper, data on the feeding habits and condition of these two populations sampled between 1998 and 1999 are presented. Both populations are zooplanktivorous, with cladocerans (Family Daphniidae) and cyclopoid copepods (Cyclops sp.) as the preferential prey for both adults and juveniles from Aguieira reservoir, while in Castelo do Bode adults feed preferentially on calanoid copepods (Copidodiaptomus albidus) and cladocerans (Family Daphniidae). Landlocked adults present lower condition than the migrating ones, while juveniles from the Aguieira reservoir show a better condition than the juveniles captured in the Mondego estuary.