Image from page 25 of "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,
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
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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Killer Whale Orcinus orca (Linnaeus, 175? Killer whales have been observed in all areas and oceans. The prevalent understanding of their distribution, often recounted, is that while they may be encountered virtually anywhere in marine waters world wide they are most abundant in colder waters of both hemi- spheres, with centers of greatest abundance within about 800km of continents. In some areas they appear to be migratory while in others they are apparently present year-round. The general patterns of dis- tribution and movement worldwide have often been described. But for most regions there are few published details on the distribution, abundance, seasonal movement patterns and habitat use. The eastern North Pacific is the exception to that rule. Here, killer whales are known from the Chukchi Sea south to the equator with no major hiatuses in distribution apparent. Reviews of literature and analyses of results of major observation programs have characterized relative abundance by major oceanic (eastern tropical Pacific) and coastal (Alaska) regions. Further, the dynamics of "populations" in areas from northern Washington to southern Alaska are under study and reasonably well known. These detailed population studies have been based largely on monitoring of naturally tagged individuals using high quality black and white photographs of the dorsal fin and post- dorsal-fin saddle and on examination of acoustic recordings for evi- dence of dialects. Such studies, begun in inland marine waters of Washington and British Columbia in the early 1970s, have recently been conducted in Southeast Alaska and southern Alaska and are being extended with less intensity to waters south of the Strait of Juan de Fuca, Washington, along the west coast of North America. From the above studies, the current dogma is that some pods and populations of killer whales are "resident", occurring all or most of the year in relatively limited "territories" or "home ranges", while others are "transient", ranging far and therefore likely to occur only spo- radically at any given site. The best described "resident" pods are known from enclosed inland marine waters with high productivity, such as those in Prince William Sound, in portions of Southeast Alaska, in the Strait of Georgia, around Vancouver Island and in Puget Sound. Transients are most often found on the outer coasts and are found in general in lesser densities overall. Along the coast of California, killer whales are often sighted well out to sea, but some move into kelp beds and into bays and inlets, as well. They are seen frequently along the coast of Baja California, particularly near island pinniped rookeries. For that reason, one might reasonably expect to meet them frequently around the pinniped-rich areas in the SCB and CINMS. It is surprising, therefore, that there are relatively few confirmed records from those regions. A recent review uncovered only 35 confirmed sightings in the SCB, Santa Barbara to San Diego, for the decade 1974-1984. A high proportion of those were recorded from nearshore areas around the northern Channel Islands. Killer whales have been seen in the SCB in most months but with slightly higher frequency in autumn and spring. After examining the limited data available from this area one researcher postulated that there were two subpopulations in the SCB, one operating in the region of the southern islands and adjacent mainland, the other in the vicintity of the northern islands (Anacapa, Santa Cruz, Santa Rosa and San Miguel) and the adjacent mainland, Port Hueneme to Point Conception. Another worker postulated that there were several "resident" pods and several "transient" ones in the SCB, supporting his hypothesis with a handful of photo-identified individuals resighted after the initial identification. One of us (SL) wrote some years ago that killer whales are seen infrequently in the *imr5hy km —mi. FIGURE 26. This male killer whale, one of seven encountered in early March 1984 off Anacapa Island, provided thrills to the passengers and crew of the We Seven and the Shearwater. (Photos courtesy of T. Donnally.)
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