sea otter extended at the rate of 

 approximately 4 km annually, with a total 

 population increase of 5% per year until 

 recently (Wild and Ames 1974). Presently, 

 a population of approximately 1,300 

 individuals occupies a range extending 320 

 km along the California coast from Point 

 Sal, San Luis Obispo County, to Point 

 Santa Cruz, Santa Cruz County (Estes and 

 Jameson 1983). However, there has been no 

 apparent increase in population size since 

 the late 1960 ' s (Estes and Jameson 1983). 

 The incidental entanglement of otters in 

 commercial fishing gear, particularly gill 

 and trammel nets, may be partly 

 responsible for the present stabilization 

 in population size (Keating pers. comm.). 



Kelp distribution and abundance can 

 be limited by sea urchin grazing (see 

 Sections 4.4.3.1 and 5.5.3); numerous 

 investigators (Boolootian 1961, Ebert 

 1968, Benech 1980, Ostfeld 1982) have 

 observed otters colonizing kelp forests in 

 central California to prey preferentially 

 on red sea urchins and abalone. Estes and 

 Palmisano (1974) asserted that sea otters, 

 by their removal of sea urchins, will have 

 a profound effect on the structuring of 

 nearshore communities. Where sea otters 

 forage over rocky substrate, sea urchin 

 densities will decrease, and if sea 

 urchins were limiting algal growth, a 

 subsequent increase in macroalgal biomass 

 will result. However, Cowen et al. (1982) 

 caution that the sea otter's influence 

 should not be generalized as the dominant 

 factor structuring giant kelp communities 

 in California. In their study area, 

 physical factors, particularly water 

 motion due to winter storms, had a greater 

 effect than the removal of urchins on a 

 nearshore kelp community. A variety of 

 factors (storms, grazing, other predators, 

 recruitment events, etc.) may have 

 significant effects on giant kelp 

 community structure (Foster 1982a; see 

 Chapters 3 and 5), and generalizations 

 about the great importance of the sea 

 otter-sea urchin interaction, based on 

 studies in other geographic areas or in 

 sites disturbed by man in southern 

 California, may not apply to the 

 heterogeneous California coast (see also 

 Chapter 5). 



4.6.2.3 



Cetaceans. 



(Eschrichtius robustus). 



Gray whale 

 Gray whales 



migrate yearly from their summer feeding 

 grounds in the Bering and Chukchi Seas to 

 their winter breeding grounds along the 

 coast of Baja California, Mexico. Each 

 leg of the journey encompasses 

 approximately 10,000 km, and takes between 

 2.5 and 3 months (Rice and Wolman 1971). 

 In both the southern and northern phases 

 of the migration, gray whales pass within 

 a few km of the California coastline. 



Scammon (1874) noted that gray whale 

 cows with their calves swim very close to 

 shore on their northern migration, often 

 passing through kelp beds. During the era 

 of active whaling in California (late 

 1800s to 1969), cow-calf pairs were 

 observed only rarely on their northern 

 migration, and were thought to use a more 

 distant offshore migrational route than 

 solitary whales (Rice and Wolman 1971). 

 As populations have increased, Poole (in 

 press) has reconfirmed Scammon 's 

 observation that cow-calf pairs undertake 

 a nearshore northern migration route, 

 while individual males and females travel 

 a point-to-point offshore route. Cow-calf 

 pairs pass along the central California 

 coastline in April and May, 2 months later 

 than solitary whales. They migrate along 

 an inshore route 200 to 400 m from shore, 

 and are often sighted along the outer 

 edges of kelp forests, or within the kelp 

 canopy itself. 



Poole (in press) recognizes two 

 possible advantages gained by cow-calf 

 pairs utilizing a nearshore route that 

 passes near kelp communities. First, kelp 

 forests may provide protection from 

 predation by killer whales. Baldridge 

 (1972) described in detail the attack of a 

 pod of killer whales on a cow-calf pair 

 near a kelp forest off Carmel , California. 

 The reaction of the cow and calf to the 

 attack was to seek refuge in a nearby kelp 

 forest. The killer whales cut off the 

 calf's retreat into the kelp. The calf 

 was subsequently killed, but the cow 

 escaped into the kelp. 



Kelp forests may also provide 

 potential food for the nursing cow. Gray 

 whales feed primarily on benthic gammarid 

 amphipods found in great abundance in 

 their Arctic feeding grounds. It is 

 generally accepted that gray whales do not 

 feed while migrating or during their 



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