FEEDING OF ATLANTIC SALMON, SALMO-SALAR L., PARR IN THE SUB-ARCTIC RIVER TENO AND 3 TRIBUTARIES IN NORTHERNMOST FINLAND

Available food and feeding of Atlantic salmon parr were studied in dif ferent parts of a subarctic river in northernmost Finland, the River T eno: in the large main stem, in a major tributary influenced by lakes, and in two minor tributaries. The highest density of benthic organism s was found in an outlet of a lake, but drifting organisms were the mo st abundant in the small tributaries. Migrant parr that move to the sm all tributaries from the main stem have better food resources in their new habitat. Plecoptera nymphs were the most important prey for salmo n parr early in the spring. Later in the summer dipterans were usually the dominant prey group. In September the importance of Plecoptera wa s emphasized in the small tributaries and the lake outlet, and that of Trichoptera in other sites. Drifting prey was used more by large than by small parr. The utilization of drifting food appeared to be relate d to the water temperature rather than to the availability of the drif t.