Layers Utilized by an ArcGIS Model to Approximate Commercial Coral and Sponge By-catch in the NAFO Regulatory Area

Abstract

This report specifically addresses Fisheries Commission Request #16: "Implement and/or further refine the existing GIS simulation/modelling framework, in conjunction with the VMS data supplied by the NAFO Secretariat ...", brought forth in the Fisheries Commission 33rd Annual Meeting Report (NAFO, 2011a). Data layers utilized by the model as well as their various means of construction are described in detail including the generation of NAFO VMS trawl lines. These VMS trawl line data were used to better understand fishing behaviour and also generate a new standard trawl length (13.8 nm) to be utilized by trawl simulations. The justification for utilizing just the Spain/EU research trawl by-catch dataset instead of the combined Canada/Spain/EU dataset for the production of higher resolution sponge and sea pen biomass surfaces is also made. It is demonstrated how this high resolution (5x5 km cell grid) Spain/EU data biomass layer could be utilized with 2000 randomly placed and oriented 13.8 nm simulation trawls to generate by-catch values, organized by thresholds, to capture the distributional extent of high concentration sponge and sea pen areas. This serves as the basis for a kernel density polygon analysis that calculates a commercial sponge and sea pen encounter threshold (Kenchington et al., 2011). Finally, using the Spain/EU only high resolution biomass surface, by-catch output from VMS trawls and their simulated 13.8 nm standard trawl line counterparts are compared.