The importance of smolt development to salmon conservation, culture, and management: Perspectives from the 6th International Workshop on Salmonid Smoltification

The 6th International Workshop on Salmonid Smoltification was held in Westport, Ireland, during September 3-7, 2001. Perhaps more so than at past workshops, this meeting took a 'salmon life cycle' approach to smoltification. Results presented at the workshop illustrated the variation in the smoltification process among species, populations and individuals, suggesting that within-species variation can be of adaptive significance. Workshop presentations also demonstrated the importance of environmental factors and culture conditions. Salmon conservation and restoration programs should work to restore aquatic systems that allow for the full suite of smolt phenotypes, ensuring their full range of adaptations. A future challenge to anadromous salmonids, which depend on both marine and freshwater ecosystems, is global warming. The rate of change in, e.g., temperature, rainfull, runoff, and ocean climate is critical to the performance of smolts and their ability to cope with change. It is essential to ensure that the genetic variation and diversity in wild stocks are not reduced, so that the capacity to adapt remains. Climatic changes will likely further compound the adverse effects stemming from anthropogenic sources such as dams, pollution, water diversion and riparian deforestation. An important question raised at the workshop is whether smolting is completed under artificial rearing conditions, which again brings us back to the question of what is a smolt? While the basic physiological blueprint associated with smoltification in hatchery and wild fish tends to be similar, cultured fish have less intense changes and differ in timing compared to smolts in the wild. Although the fundamental genetic basis for smoltification remains, a concern is that the population-level variation in smolt phenotypes is being reduced. Enhancement operations have been initiated in most salmon-producing regions to compensate for loss of natural production. While the interests of salmon conservation and exploitation are superficially similar, i.e., to ensure a viable population with a good adult run, obvious differences are emerging. Workshop presentations and discussions focused on ways of combining the interests of conservation and exploitation. Local adaptation should be maintained in hatchery-enhanced stocks and combined with a move towards a more natural rearing environment. This is likely to benefit both conservation efforts and fisheries interests. Current advances in biology are likely to have a major influence on our approach to smolt research. Still, the 'traditional' ecological, physiological, behavioral and environment-fish interaction studies at the organismal level will be critical for interpretation of findings at the molecular, cellular and organ levels, and are vital as input for the management of our wild and reared salmon stock. Perhaps once all of this has been accomplished we will have come to terms with the vexing question: what is smolt? However, even if this question remains unanswered, our increased understanding of smolts as a critical stage in the life history of salmon will improve our ability to conserve, enhance and enjoy this vital natural resource.