File:Cetaceans of the Channel Islands National Marine Sanctuary - prepared for National Oceanic and Atmospheric Administration, Channel Islands National Marine Sanctuary and NOAA, National Marine Fisheries (20580125122).jpg

Title: Cetaceans of the Channel Islands National Marine Sanctuary / prepared for National Oceanic and Atmospheric Administration, Channel Islands National Marine Sanctuary and NOAA, National Marine Fisheries Service by Stephen Leatherwood, Brent S. Stewart, Pieter A. Folkens
Identifier: cetaceansofchan00leat (find matches)
Year: 1987 (1980s)
Authors: Leatherwood, Stephen; Stewart, Brent Scott; Folkens, Pieter A; Channel Islands National Marine Sanctuary (Agency : U. S. ); United States. National Marine Fisheries Service
Subjects: Whales California Channel Islands.
Publisher: Santa Barbara, Calif. : The Sanctuary
Contributing Library: Penn State University
Digitizing Sponsor: LYRASIS Members and Sloan Foundation

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Sperm Whale Physeter macrocephalus (Linnaeus, 1758) Sperm whales are found world wide in pelagic waters. Only adult males routinely venture above latitude 40 in either hemisphere; all other animals remain year-round, and most adult males remain during breeding seasons, in waters between latitudes 40 N and 40 S. One often quoted recent paper estimated that there were some 800,000 adult sperm whales or 1.5 million total sperm whales, including calves and juveniles, world wide. Nearly half of those are believed to be in the North Pacific. There is still debate about the identity of sperm whale stocks in the North Pacific, debate fueled by the fact that the last area of major exploitation of sperm whales in the world has been the waters off Japan. Some workers postulate that there are three stocks — Asian, central, and American — while others argue that there are only two — western (Asian) and eastern (American). Whatever the correct defini- tion of relationships among north Pacific sperm whale groups, howev- er, any animals occurring in the SCB and CINMS belong to the easternmost stock. Large numbers of sperm whales were killed in the North Pacific bv nineteenth century yankee whalers, mostly in waters south of latitude 40 N. Modern shore-whalers killed just over 7,000 between 1905 and 1971, including over 1,000 off California. But the most significant impact on the populations has been that from takes by Japanese and Soviet whalers, operating from land stations and pelagic fleets. Such operations killed nearly 269,000 sperm whales between 1910 and 1976. Effort and catches in those fisheries increased after World War II, resulting in a peak kill of over 16,000 sperm whales in 1968. Pelagic whaling for sperm whales has stopped. The fate of Japanese shore stations remains a disputed matter as nations argue and posture, anticipating the start of the IWC's ban on whaling, effective in the 1986 season. Political settlements between the US and Japan may prolong the life of Japanese shore fisheries through 1989, but the matter is, at present, in US Federal Court. Failing a major rebirth of the whaling industry, however, North Pacific sperm whales should flourish under impending protection and reinvade numerous areas in which their numbers have been reduced by whaling. Sperm whales show a clear preference for deep waters at the continental shelf edge, on the continental slope, or over deep offshore canyons. However, in areas where such deep water canyons intrude into the continental shelf, they occassionally stray over shallower shelf waters. Sperm whales are known to be fairly common off Central California from at least November to April and were taken by yankee whalers operating off central and southern Baja California at those times of year. Movements of sperm whales past the latitudes of the SCB appear, from the few offshore surveys at those latitudes, to occur primarily seaward of the shelf edge. Nevertheless, we have learned of 11 verified records of sperm whales over continental shelf waters of the northern SCB since about 1965. These include seven from waters immediatelv adjacent to the CINMS, the most recent just inshore of east Anacapa Island in October 1985. At the latitudes covered by the CINMS one might meet with any age/sex of sperm whale, especially in warm water years when pelagic squid invade in greater than usual numbers. To date, however, reported sightings have involved large solitary animals, presumably adult males. FIGURE 14. Sperm whales, ordinarily creatures of the deep ocean, do occassionally wander over the SCB, as did this large male off San Nicolas Island in April 1974. We are aware of only eleven verified records of sperm whales over continental shelf waters in the northern SCB since 1965. (Photo by S. Leatherwood.)
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