Metapopulations and salmonids: a synthesis of life history patterns and empirical observations

Metapopulation theory has attracted considerable interest with reference to the salmonids. There has been little empirical evidence, however, to guide the evaluation or application of metapopulation concepts. From knowledge o f salmonid life histories and our own work with bull trout (Salvelinus conf luentus), Lahontan cutthroat trout (Oncorhynchus clarki henshawi) and wests lope cutthroat trout (Oncorhynchus clarki lewisi), we suggest that simple g eneralizations of salmonid metapopulations are inappropriate. Although spat ial structuring and dispersal mechanisms are evident, the relevance of exti nction and colonization processes are likely to vary with life history, spe cies, scale, and landscape. Understanding dispersal, the role of suitable b ut unoccupied habitats, and the potential for extinction debts in non-equil ibrium metapopulations are key issues. With regard to conservation of salmo nids, we suggest that efforts to understand and conserve key processes like ly to influence the persistence of populations or metapopulations will be m ore successful than efforts to design minimal habitat reserves based on met apopulation theory.