Benthic habitat mapping of an Atlantic cod (Gadus morhua) refuge, Smith Sound, Newfoundland, Canada

Abstract

After the northern cod collapse, a surviving component of this stock took refuge in Smith Sound, a sub-arctic Newfoundland fjord. While benthic habitats used by recovering fish populations can provide important ecological services, habitats within this refuge have not been mapped. This study mapped Smith Sound’s benthic habitats using Van Veen grab and videos samples of the seafloor. Habitats were mapped by combining ground truthing data with multibeam bathymetry terrain derivatives using a Maximum Likelihood Classifier. Eight habitats were observed and mapped with an overall map accuracy of 84.76% (Kappa 80.40%). Multiple habitats were observed that could be linked to cod ecology and services of an ecological refuge. Known spawning areas were characterised predominantly by Sandy Mud habitat, bordered by Small Boulders and Gravel habitats. Sub-optimal habitat consisted of Gravelly Muddy Sand with Small Boulders, bordered by Large Boulders. The habitats were linked to cod ecology providing shelter, sustenance and opportunities for reproduction, all services required by a refuge.