Dynamics, assessment and management of exploited natural populations

Abstract

This chapter discusses the dynamics, assessment, and management of exploited natural populations. All scallop stocks are structured as “metapopulations” in which subpopulations of sedentary post-larval individuals are connected with each other through the dispersal of pelagic larvae. The metapopulation is a useful conceptual framework for the analysis and management of benthic fisheries. Emphasis on spatial structure brings with it, the need to identify appropriate spatial scales for the observation, analysis and management of exploited scallop stocks. The hierarchy of spatial scales presented by Orensanz and Jamieson is adopted in the chapter. The primary factors tuning year-class-strength are those that affect advection and survival of pelagic larvae. These factors pertain largely to oceanographic conditions. It is natural that research on modulation of year-class-strength and the search for signs of climatic forcing focus on abundance indices aggregated at relatively large spatial scales. The empirical evidence about the influence of climate on larval availability and recruitment is considered. The transition between the two stages—namely, pelagic larvae and recruits is modulated by factors other than larval availability. The elusive relationship between aggregate spawning stock and recruitment is also discussed.