| Abstract | A process-based mechanistic model for growth of larval fish is developed analogous to one proposed by Bertalanffy (1957). It extends his work to model anabolism explicitly as a function of the geometric relationships between the growing larva and its yolk supply. The estimated parameters are tightly coupled to an exponential function of temperature R2 > .99. Using this model, larval salmon growth under various laboratory conditions is simulated and the importance of temperature and egg size for controlling development is demonstrated. Because the temperature conditions to which the larvae are exposed after spawning determine their developmental rate and size, emergence of the fry can be anticipated based on temperature controlled development. Growth of naturally-spawning Methow River spring and summer chinook is simulated to demonstrate how spawning behavior is timed to optimize the fitness of these two stocks in different ways. Spring chinook grow efficiently and emerge as productivity is increasing. Summer chinook do not grow efficiently because their growth period is constrained by lethal temperatures that preclude earlier spawning and a high probability of scour events that preclude later emergence. |