Incorporating the spatial component of fisheries data into stock assessment models

Fisheries-dependent and independent data have a strong spatial component. T hese data are also multi-dimensional making them difficult to visualize and analyze, prompting the use of spatial analysis to facilitate an understand ing of their relationships. One aspect of fisheries data that is often igno red is the distribution and abundance of a particular resource and the fish ing patterns of its harvesting fisheries. In order to improve management ad vice, stock assessors need to incorporate the spatial component of these da ta into an existing assessment framework. This paper presents a three-dimen sional visualization of the age-structure and fishery dependent and indepen dent data associated with the sparid fish Pterogymnus laniarius on the Agul has Bank, South Africa. A spatially-referenced spawner biomass per-recruit model is developed to illustrate the applicability of incorporating spatial ly referenced information in providing management advice. The model provide d evidence that, even on a spatial scale, fishing mortality is significantl y correlated to fishing effort. Areas of high levels of spawner biomass are noted, all of which corresponded to those geographic areas with a combinat ion of low fishing effort and high adult biomass. (C) 2000 International Co uncil for the Exploration of the Sea.