Marine mammal monitoring and habitat investigations during CalCOFI surveys

To understand cetacean ecology and habitat, a new component has been added to the CalCOF1 ecosystein studies that have beer) conducted offshore of southern California over the last half century. In 2004, we initiated visual and acoustic line-transect surveys during)(1 CalCOFI cruises and long-term acoustic monitoring at selected CalCOFI stations. Visual monitoring provides excellent data for highly visible species in calm to moderate weather. The most commonly sighted species oil visual surveys conducted between July 2004 and November 2005 were blue, fill, humpback, and sperm whales, and Pacific white-sided, short-beaked common, and long-beaked common dolphins. Blue, fin, and sperm whales were sighted more frequently in summer to fill months, while northern right whale dolphins and Dall's porpoises were sighted more frequently in winter and spring. Spatial patterns of occurrence are evident for all species within the study area.