canopy maps, he postulated a change from 

 Nereoystis to Macrocystis after otters 

 removed sea urchins. While this may be 

 the case for some sites in central 

 California, the evidence is equivocal for 

 others. Sea urchins are quite patchy in 

 their distribution and effects, and there 

 is often not a straightforward 

 relationship between their abundances and 

 that of particular kelp species (see 

 references in previous section). In 

 addition, winter storms and turbulent sea 

 conditions can affect kelp abundance; 

 Nereocystis tends to replace Macrocystis 

 in such cases (e.g., Cowen et al . 1982) . 

 To resolve these questions, a better 

 understanding is needed of the effects of 

 sea urchins in kelp forests without 

 otters. Macrocystis communities can 

 certainly exist in the presence of this 

 grazer. Giant kelp communities are 

 vaiable in space and time, however, and 

 dense aggregations of sea urchins may be 

 the exception rather than the rule. 



The historical evidence for the 

 effects of sea otters is also somewhat 

 equivocal. Simenstad et al. (1978) 

 examined evidence from Aleut middens in 

 Alaska and concluded that alternate stable 

 states existed in nearshore communities. 

 They argued that the strata containing 

 large quantities of sea urchin and limpet 

 shells coincided with the absence of 



otters, due to hunting by Aleuts. The 



presence of fish remains coincided with 



times when otters were present, and 

 macroalgae predominated. 



There is also evidence in the middens 

 in Monterey (Gordon 1974) and on San 

 Nicolas Island, off southern California, 

 that prehistoric man hunted sea otters. 

 Dayton and Tegner (1984a) pointed out the 

 large numbers of abalone shells seen on 

 the island, suggesting that aboriginal man 

 had a significant impact on the nearshore 

 community. 



Estes and Van Blaricom (in press) 

 reviewed the data on the fluctuations in 

 many shellfish populations and the 

 possible effects of sea otters. The 

 advent of otters and the decline of many 

 shell fisheries are often coincident with 

 increased fishing pressure, pointing to 

 competition between modern man and otters 

 for particular resources. They concluded 

 that the near extinction of the sea otter 

 permitted the development of shell 

 fisheries in the first place. While these 

 questions are interesting and relevant, 

 the interactions between otters, 

 particular fisheries, and natural 

 variability of populations are complex and 

 have forced the issues more into the 

 political province than an experimental 

 one. 



107 



