The Arctic charr of Muzelle lake, at 2105 m in the Oisans massif (French Alps) feed most actively, essentially on Chironomidae, during the 6 or 7 weeks following the melting of the ice. The period of maximum growth corresponds to the time when food availability is at its highest, and it does not overlap with the period of maximum temperatures. Males and females mature at age 3 years but only half of the females of age 3 years spawn each year. This ratio of spawning females is constant from 3 to 6 years, the latter being maximum age observed in this lake. Each female spawns only twice at the most during its lifetime.