Sperm Whale 



Physeler macrocepkalus (Linnaeus, 1758) 



Sperm whales are found world wide in pelagic waters. Only adult 

 males routinely venture above latitude 40 m 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 he 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 ot sperm whales were killed in the North Pacific by 

 nineteenth century yankee whalers, mostly in waters south of latitude 

 4o°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 IL 

 resulting in a peak kill ot over 16,000 sperm whales in 1968. Pelagic 

 whaling tor 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 lite ot Japanese shore fisheries through 1989, but the matter is, at 

 present, in US Federal Court. Failing a major rebirth ot 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 tor deep waters at the 

 continental shell 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 ot the 

 SCB appear, from the few offshore surveys at those latitudes, to occur 

 primarily seaward of the shelf edge. Nevertheless, we have learned of 1 1 

 verified records of sperm whales over continental shelf waters of the 

 northern SCB since about 1965. These include seven from waters 

 immediately adjacent to the CINMS, the most recent just inshore ot 

 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, howex'er, reported sightings ha\'e 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 

 b\- S. Leatherwood.) 



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