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.