macrophytic algae. Under such a regime of preda- 

 tion, large herbivores are usually restricted to 

 refugia protected from carnivores (Lowry and 

 Pearse 1973, Cooper et al. 1977). This was appar- 

 ently the undisturbed condition of California sub- 

 littoral communities (Rashkin 1972). The super- 

 abundance of large herbivores upon which the 

 commercial shellfish industry is based is appar- 

 ently an artifact of the historic reduction in sea 

 otter numbers. Herbivore-carnivore numbers can 

 be expected to return to equihbrium following 

 the sea otter's reoccupancy of its former range. 



AUTHORITIES 



Ronald J . Jameson 



National Fish and Wildlife Laboratory 



Piedras Blancas Field Station 



P.O. Box 67 



San Simeon, California 93452 



Karl W. Kenyon 

 U.S. Fish and Wildlife 

 11990 Lakeside Place N.W. 

 Seattle, Washington 98125 



Service (retired) 



A. M.Johnson 



National Fish and Wildlife Laboratory 



Anchorage Field Station 



4454 Business Park Boulevard 



Anchorage, Alaska 99503 



James E. Estes 



National Fish and Wildlife Laboratory 



CCMS; Applied Science Building 



University of California 



Santa Cruz, California 95064 



J. E. Vandevere 

 93 Via Ventura 

 Monterey, California 93940 



Tom Loughlin 



National Marine Fisheries Service 



Marine Mammals and Endangered Species Div. 



F-33 NMFS 



Washington, D.C. 20235 



D. Miller and J. Ames 



California Department of Fish and Game 



2201 Garden Road 



Monterey, California 93940 



PREPARER'S COMMENTS 



Recently there has been some controversy 

 over the systematic status of the southern popula- 

 tions of sea otter (Roest 1973, 1976; Davis and 

 Lidicker 1975). Pointing to an apparent latitudi- 

 nal cline in some skull measurements, Roest 

 (1973) contended that the southern sea otter is not 

 subspecifically distinct, but represents one end of 

 a size continuum. Davis and Lidicker (1975) 

 argue that available evidence is best interpreted to 

 suggest that a genetically distinct group of sea ot- 

 ters exists off the California coast. 



Subspecies are often recognized primarily on 

 morphological criteria, which usually are the 

 result of genetic divergence due to selection with- 

 in different sets of environmental parameters. To 

 date, most attention has been paid to relatively 

 few cranial measurements in sea otters. The north- 

 ern and southern populations of the sea otter ap- 

 pear to display some differences in diet and ana- 

 tomy as well as in cranial morphology (Wood- 

 house et al. 1977, Miller 1974), which may or 

 may not be genetically based. It is certainly pos- 

 sible that selection has resulted in some genetic 

 divergence between these populations. However, 

 we suggest the application of modern systematic 

 techniques aimed at assessing this genetic distance 

 between populations (such as karyology, protein 

 electrophoresis, immunology, and perhaps DNA 

 annealing) to adequately resolve this controversy. 

 Meanwhile, it would be inappropriate to sacrifice 

 the protection afforded the recovering southern 

 populations to a disagreement over an as-yet 

 unresolved taxonomic issue. This issue was ad- 

 dressed by the USFWS in the Federal Register (14 

 January 1977): "This question actually is not 

 relevant to the matter at hand, because sections 3 

 and 4 of the Act allows [sic] the listing of popu- 

 lations of species in portions of their range, as 

 well as entire species and subspecies. Since the 

 southern sea otter does form a significant popu- 

 lation, it can be treated independently under the 

 Act, regardless of its taxonomic status. The Ser- 

 vice decided, however, to utilize the subspecific 

 designation Enhydra lutris nereis in this rule- 

 making, although this decision had no connection 

 with the decision to list as threatened." 



