Interactions between wild and introduced Atlantic salmon (Salmo salar)

Wide latitude exists for genetic, behavioural, and ecological interactions between introduced and wild Atlantic salmon (Salmo salar L.). These can occur at all stages of the life cycle and across the range of natural environments the species exploits. Because of the large number of variables and scales involved, each interaction scenario and its outcome is expected to be unique. However, as a general rule, interactions are likely to be negative in their effect on the viability of wild populations. In theory, it ought to be possible to develop approaches for managing interactions, but in the particular case of genetic effects this is especially difficult. It is possible to put forward two guiding genetic principals for intentional introductions. Firstly, when introductions are used to maximize local abundance, genotypic diversity must be maintained so that mean individual fitness remains undiminished after interaction has occurred. Secondly, when introductions are used to alter local frequencies of phenotypes, the population's capacity to remain viable in the longterm must not be impaired. Both principals are pragmatic and aim to conserve or restore the genetic capacity of populations to evolve rather than seeking the preservation of their current condition.