Toward an Ecosystem Approach to Bottom Trawling in Canada

10 overview of bottom trawlingof B.C.’s continental shelf; however, precise geo-referenced data (i.e., GPS coordinates oftrawl tows) has only been systematically collected for a decade. Trawling effort (i.e., numberof hours of trawling) was historically much higher than it is today and therefore it is fairto assume that these areas have been trawled several times during the past 60 years. Giventhat the most sensitive habitats are destroyed from the first few fishing events, it is unlikelythat any large tracts of sensitive habitat still exist along the west coast of Vancouver Islandin the depth range of 150 to 1,200 metres.TABLE 1Table showing the area bottom trawled in British Columbia by depth strataand Pacific Fisheries Management Areas from 1996 to 2005. Trawled areabased on trawl tows transecting one-square-kilometre grid squares. 25 Thedata in these tables were derived from an overlay of a GIS shapefile ofmanagement areas (provided by DFO) and a bathymetry combined withpublished outputs of cumulative trawled area by management area. 26TOTAL AREA (KM2) IN DEPTH STRATA AND PFMADepth 3CD 5AB 5CD 5E All areas0-150 13283 14771 27833 2523 58411150-500 3746 14574 14434 3817 36570500-1200 4996 2539 40 3583 11158All Depths 22025 31884 42307 9924 106140cumulative new area (KM2) trawled (1996-2005) by Depth strata and pfmaDepth 3CD 5AB 5CD 5E All areas0-150 4305 3918 5550 10 13783150-500 3762 7408 4249 1869 17288500-1200 4677 871 1704 7249All Depths 12744 12194 9799 3583 38320percentage of area trawled by depth strata and PFMA (1996-2005)Depth 3CD 5AB 5CD 5E All areas0-150 32 27 20 0 24150-500 100 51 29 49 47500-1200 34 0 65All Depths 58 38 23 36 36