Nearshore Habitat Classification

Two first nations on northern Vancouver Island have been concerned about the impact of net-pen fish farms, specifically on nearshore traditional harvesting that includes intertidal shellfish and nearshore invertebrates. This nearshore habitat project was meant to establish a spatial framework for understanding nearshore resources and their sensitivities to man-made impacts. The project involves approximately 1,500 km of shoreline in the Broughton Archipelago. Two datasets were used to define nearshore habitat units: (a) Canadian Hydrographic Service (CHS) bathymetry data, and (b) the BC ShoreZone dataset (intertidal habitat mapping of substrate, exposure and biota);in practice, depth ribbons were delineated by isobaths and then the ribbons were segmented into polygons (habitat patches) based on the alongshore units of ShoreZone. Over 20,000 habitat patches have been defined. Twelve nearshore habitats were identified, based on combinations of depth class, substrate class (from existing CHS substrate data) and energy class (from tidal model data). Characteristic biotic associations were linked to each habitat type and associated sensitivities assigned. Overall, the analysis suggests that about 12% (62 km²) of nearshore has high sensitity where potential pollutant contamination is more likely.