USE OF DRIFTING INVERTEBRATES BY YOUNG-OF-YEAR BROWN TROUT IN STREAM-MARGIN HABITAT

We studied the feeding dynamics of young-of-year (YOY) brown trout (Sa lmo trutta) inhabiting stream-margin habitat of a mountain stream duri ng August and September. We found invertebrates in fish stomachs throu ghout 24-h sampling periods. The abundance, of items in stomachs incre ased with the density of drifting invertebrates after dark. Compositio n of stomach contents and composition of drifting invertebrate samples were related, but Ephemeroptera larvae had Positive electivity indice s more frequently than other taxa. The mean lengths of invertebrates i n stomachs were greater than those in samples of drifting invertebrate s.