LONGEVITY, BODY SIZE, AND GROWTH IN ANADROMOUS BROWN TROUT (SALMO-TRUTTA)

Longevity in 25 populations of anadromous brown trout (Salmo trutta) showed a significant trend with increasing life span at latitudes of 58-70-degrees-N in Norway, with the largest change from 58 to 60-degrees-N. Moreover, longevity was negatively correlated with temperature and growth rate in freshwater and at sea. Body size was negatively correlated with water temperature and growth rate in freshwater, but not with latitude or water temperature and growth rate at sea. Thus, conditions influencing development and metabolic rates in fresh water seem more important than conditions in the sea in determining variation in longevity and body size of anadromous brown trout. Our results support the hypothesis that interpopulation variation in longevity and body size is influenced by rate of metabolism, chiefly influenced by ambient water temperature.