Individual variation in the physiology of early life stages of fish: Implications for future fitness and susceptibility to environmental change.

The behavioural and physiological characteristics of an individual are inherited from its parents but can also be influenced by the environment in which it develops. For example, the way in which an individual interacts with members of its own species, e.g. fighting and competition, can affect its future growth and development. Individuals within populations of salmonid fish (i.e. salmon and trout) will all differ, albeit slightly, in the way that they function physiologically and how they behave. This variation leads in particular to differences in competitive ability. As a result, some fish will be better at acquiring food resources than others. These fish will consequentially grow faster and this will go on to magnify the differences among individuals of the same population. But what factors influence the initial degree of variation in both behavioural and physiological characteristics among groups of fish? What makes the competitive ability of some fish better than others? Do environmental factors within the gravel nests where salmonid eggs are laid affect competitive ability of fish later in life? Does the amount of stress experienced by a female fish before spawning influence the level of variation in fitness of her offspring? Can small differences in the stream environment while young fish are developing, such as increases in temperature, influence their behavioural and physiological characteristics? This project aims to answer these questions. Understanding the factors underlying variation in individual behavioural and physiological characteristics in salmonid fish is of crucial conservational importance. Protecting our native fish populations is dependent upon a scientific understanding of their underlying biological processes, such as those influencing behavioural and physiological fitness of individuals.