Growth, reproduction and feeding of dwarf Arctic char, Salvelinus alpinus, from an Alpine high mountain lake

The Arctic char population (Salvelinus alpinus) from a shallow high mountain lake in the Alps (Oberer Plenderlesee, Kuhtai, Tyrol, Austria, 2344 m a.s.l.) was subjected to seasonal studies on growth, reproduction and feeding. Growth rate and condition factors were low, and the life-span was relatively short (up to 10 years). Males matured in their third year, the majority of females one year later, partly with spawning cycles of more than one year. Ovaries started to grow in July and attained a weight of 13.3% in October. Atretic eggs (10-30%) were found in one third of adult females. The relative number of eggs decreased with age and size of the fish. The relative liver weight increased with gonadal development by a factor of 2.5. Compared to low-altitude populations the relative liver weight of female Arctic char from Oberer Plenderlesee is significantly higher, indicating compensation for the low environmental temperature. Fish fed during an seasons; the highest values of stomach contents, however, were found at the period of ice-break and in autumn. In winter, Arctic char fed almost exclusively on chironomid larvae. During the ice-free period, the diet was more complex with a predominance of flying insects.