The impact of man on the biosphere is profound. Quite apart from our capacity to destroy natural ecosystems and to drive species to extinction, we mould the evolution of the survivors by the selection pressures we apply to them. This has implications for the continued health of our natural biological resources and for the way in which we seek to optimise yield from those resources. Of these biological resources, fish stocks are particularly important to mankind as a source of protein. On a global basis, fish stocks provide the major source of protein for human consumption from natural ecosystems, amounting to some seventy million tonnes in 1970. Although fisheries management has been extensively developed over the last century, it has not hitherto considered the evolutionary consequences of fishing activity. While this omission may not have been serious in the past, the ever increasing intensity of exploitation and the deteriorating health of fish stocks has generated an urgent need for a better understanding of evolution driven by harvesting and the implications of this for fish stock management. The foundations for this understanding for the most part come from recent developments in evolutionary biology and are not generally available to fisheries scientists. The purpose of this book is to provide this basis in a form that is both accessible and relevant to fisheries biology.

Inhalt

I - Selection Differentials.- Fishing as a cause of evolution in fishes.- Selection differentials in male and female North Sea plaice and changes in maturation and fecundity.- Growth and fecundity changes in flatfish.- The effects of fishing on the timing of maturity in North Sea cod (Gadus morhua L.).- Influence of human activity on properties of Atlantic salmon populations.- II - Reaction Norms.- Norms of reaction in fishes.- Individual variation in acquisition/allocation reaction norms.- Reaction norms for reproductive traits in brook trout and their influence on life history evolution affected by size-selective harvesting.- III - Selection Responses.- Trade-offs and genetic correlations among life-history traits: theory and simulation.- The evolution of size and growth in harvested natural populations.- Cohort-structured populations, selection responses, and exploitation of the North Sea cod.- IV - Management and Evolution.- Evolutionary stable optimal harvesting strategies.- Ecogenetic analysis and evolutionarily stable strategies in harvested populations.- Catastrophe-type regulation of pelagic fish stocks: adaptive management for evolving resources.- Size-selective harvesting and age-at-maturity. I: some theoretical implications for management of evolving resources.- Size-selective harvesting and age-at-maturity. II: real populations and management options.- Consequences of size-selective harvesting as an evolutionary game.- List of Participants.