Abundance and Distribution of Harbor Porpoises and Other Cetaceans in the San Juan Channel: Tides and Bathymetry

Abstract

The Salish Sea, an area of complex oceanography and bathymetry, supports a number of apex cetacean species. In the last decade, anomalous sightings of cetaceans have become more frequent and shifts in species abundance have occurred. This 2014 Pelagic Ecosystem Function (PEF) study, using large and fine scale surveys in the San Juan Channel (SJC), determined that cetacean mean density was unusually low but species composition was more diverse than previous years, perhaps due to anonymously warm surface water. The relationship between tides, bathymetry and harbor porpoise abundance at small scales were different than those found previously in the region.