Assessment of the impacts of bottom trawling on marine foundation species in northern Hecate Strait, British Columbia

I examine impacts of bottom-trawling on benthic foundation species (FS) in northern Hecate Strait, BC using photographic analysis of the benthos conducted over a gradient of trawling effort, substrate, and depth. Between 14-22 photos, from 31 remote-operated-vehicle transects, were analyzed to assess proportional coverage of FS. Using quasi-binomial regression I found that FS coverage is negatively associated with (in order of importance) the proportion of soft substrate (βPsm = -1.09; SE = 0.15), depth (βd = -0.31; SE: 0.29), trawled area (βS14 = -0.06; SE = 0.15), and surficial geology “sand/gravel” (βsand/gravel = -0.06; SE: 0.25). Surficial geology, inferred from substrate maps, is the least important variable associated with FS coverage, due to misclassification of substrate type at the scale of the survey. I found the true magnitude of trawling impact on FS to be uncertain due to inadequate power and contrast in my survey design.