This tendency for salmonids to form these distinct populations make them a particularly challenging group to manage and conserve. Nowhere is this more important than in commercial arenas, as these fish contribute $billions to the global economy by way of commercial fisheries, angling tourism and eco-tourism. Salmonids also play an important role in the ecosystem especially as a food source for many top predators such as the brown bears of North America. It is essential then that the process of local adaptation in these species' be well understood.
This week, a new study has shed some light on the temporal scale over which these evolutionarily significant changes can occur. This research has shown that genetic changes associated with earlier migration in pink salmon can evolve in as little as 30 years. The study demonstrated that a population of these salmon tended to migrate to spawn, on average, two weeks earlier than 40 years ago. A change thought to have evolved in response to rising stream temperature associated with climate change. It is known that high stream temperature can lead to egg mortality, thus an adaptation toward earlier migration is likely to decrease the risk of this occurring, thereby increasing fitness.
This finding suggests that wild populations of salmonids may indeed be able to cope (at least in the short term) with the high rates of change associated with current climate trends, however the additional evolutionary implications associated with such rapid adaptive changes are unknown.