THE IMPLICATIONS OF MATERNAL DECISIONS FOR OFFSPRING GROWTH AND SURVIVAL

Many of the factors determining embryo and early juvenile growth and survival are intimately linked to maternal traits in salmonids. Females choose the spawning sites and times, construct the nests and deposit the nutrient-rich eggs. In Atlantic salmon, female breeding success (i.e., number of her embryos surviving to emergence) shows a strong positive relation to body size due in part to increased fecundity. Increased fecundity, however, is only part of the story, because while female fecundity typically increases at a declining rate with body size, breeding success increases exponentially. Thus large females are producing fewer eggs, but are achieving higher breeding success per unit body size than are small females (Fleming 1998). The female through her effects on nest quality and survival largely determines the probability of embryo survival during incubation. When the eggs hatch, the small juveniles still have a considerable amount of nutrients and energy stored in the yolk-sac, as a result of maternal provisioning. Once the yolk sac is absorbed, the juveniles emerge from the gravel into th