Marine protected area design and the spatial and temporal distribution of cetaceans in a submarine canyon

The Gully, the largest submarine canyon off the coast of East Canada, is cu rrently under consideration as a marine conservation area, primarily becaus e of the increasing interset in oil and gas production on the Scotian Shelf . Cetaceans, as a guild of abundant, large organisms that are relatively se nsitive to such threats, provide a reliable means to determine the boundari es for a conservation area in this region. We compared the abundance of cet aceans between the Gully and the other parts of the Scotian Shelf and Slope and found that abundance was higher in the Gully. We also assessed cetacea n distribution and relative abundance within the Gully relative to search e ffort for several effort for several apatial and temporal parameters: depth , slope, sea surface temperature, and month. Distribution within the Gully was most strongly correlated with depth, but was also significantly correla ted with sea surface temperature and month. Five of the 11 cetacean species commonly found in the Gully, and all those for which the Gully formed sign ificant habitat on the Scotian Shelf, were concentrated in the deep (200-20 00 m) mouth of the canyon. We suggest that a year-round marine protected ar ea is necessary for the Gully. A core protection zone should be defined in the Gully based on depth and bounded by the 200-m isobath. A buffer zone ar ound the core zone should be defined to provide protection from activities with further-reaching effects, such as noise, dredging, and chemical pollut ion.