Inter and Intra Cohort Variation in the Life History of Arctic Charr (Salvelinus alpinus)

摘要

We tested if Arctic charr matured sexually at a specific size or age, or if maturity was correlated to growth rate as a reaction norm. This was studied in a population where fishing was markedly reduced during a four-years period because of radioactive fallout from the Chernobyl accident. Within cohorts, age at maturity was correlated with growth rate. Fast growing males matured at a younger age and smaller size than slow growing individuals throughout the study period. Fast growing females also matured at a younger age than slow growing individuals but size at maturity was similar for early and late maturing females when growth conditions were good. When growth was poor, early maturing individuals were smaller than late maturing ones. Between cohorts, male age at maturity was more variable than female age at maturity. The proportion of early maturing males decreased with decreasing size at maturity, whereas this proportion varied little among females. Sexual maturity thus appears to be more closely related to age among females than males, indicating a genetic component for maturing at a specific age.