Effects of climatic temperature change on growth, survival, and reproduction of rainbow trout: Predictions from a simulation model

The effects of changes in the annual temperature cycle on energy acquisition and the allocation of that energy to respiration, growth, and reproduction of female rainbow trout (Oncorhynchus mykiss) are evaluated using a new type of simulation model. We tested the effects of warmer (+2 and +4°C) and cooler (-2°C) water temperature cycles. We used Monte Carlo filtering techniques to define the range of parameter sets capable of generating realistic behaviour for individual female rainbow trout over a single reproductive cycle under the baseline temperature regime. The base temperature scenario generally resulted in maximum growth and reproductive success. Shifts in the annual temperature cycle of +2 and -4°C decreased growth and reproductive success, but most females were in better physiological condition. The -2°C scenario resulted in reduced growth, physiological condition, gonad index, and reproductive success. The effects of shifts in the annual texture cycle varied substantially between individual model trout having relatively small differences in parameter values. These differences may be considered analogs of genotypic differences among individual trout in the field. The long term implications of variability in physiological parameters between individuals are not easily evaluated experimentally Models are an ideal tool for heuristically exploring such implications.