Dynamics, assessment, and management of exploited natural scallop populations

Abstract

This chapter reviews advances made in the study of the structure and dynamics of scallop populations and in the development of new approaches for the assessment and management of exploited scallop stocks. Significant progress in the understanding of larval transport and connectivity of scallop populations has been achieved in recent years through the use of coupled biophysical modelling in combination with novel population genetics techniques. The assessment of abundance and distribution of scallops stocks has benefitted from recent technological developments, particularly in the fields of acoustics and underwater photography. These developments have led to mapping scallop distributions in relation to bottom type characterisations obtained from multi-beam sonar data, groundtruthed using conventional in situ sampling, including underwater imagery. Underwater cameras have also become more common, replacing conventional fishing gears used for periodic monitoring surveys. Management has increasingly focused on spatial harvesting strategies that recognise the existence of spatial gradients in scallop productivity, the non-random allocation of fishing effort and the large inter-annual variability that is typical of scallop recruitment. The use of management strategy evaluation methods to design harvest control rules that are suited to the fishery specific characteristics, and monitoring capabilities is a promising area of new development. Concerns about habitat impacts of dredges and trawls used for harvesting scallops have received much scientific attention as the scope of fisheries assessment has expanded beyond the target species to include broader ecological effects of fishing.