124 



tion of the testes, and hypertension. Hypertension can be induced 

 in rats when renal molar cadmium to zinc ratios exceed 0.35. Two nor- 

 mal otters tested had ratios close to this value, 0.32 and 0.35, which 

 suggests that this condition may be common in the otter herd.^ These 

 extremely high cadmium concentrations, 4.2 to 16.1 p.p.m. in their 

 livers and 12.0 to 43.3 p.p.m. in their kidneys, have prompted us to 

 begin a search for its source. 



In testing for mercury, six adult or near-adult sea otters were 

 analyzed for comparison with California sea lions.- Although brain 

 and kidney levels were similar, sea lion liver values were an order of 

 magnitude higher than those found in the otters (42 versus 4 p.p.m.). 

 The range in sea otters was 0.78 to 7.35 p.j).m. Whether this discre- 

 pancy is a reflection of the otters' diet — primarily mollusks,^ which 

 are not as high in the food chain as the fish diet of sea lions — or a basic 

 physiological difference, remains to be seen. 



The accumulation of toxic levels of pesticides and other environ- 

 mental poisons may eventually cause such a reduction in the number of 

 sea ott«rs as to make the efforts of Alaska's sea otter harvesting pro- 

 gram and attempts in California to set limits on their population seem 

 ludicrous. 



Testifying in Sacramento against control of the southern sea otter 

 population on April 6, 1970, Dr. Robert T. Orr, associate director of the 

 California Academy of Sciences, and curator of its departments of 

 ornithology and mammalogy, said, in part : "Wliat will (this Califor- 

 nia bill) do? It proposes to curb sea otters which are barely past the 

 danger point. Why ? So that a small group of market hunters who are 

 commercializing on something that belongs to all of us can continue 

 their exploitation to produce a gourmet item." 



Attempts of some commercial and sportsmen's groups to encourage 

 legislation that would "manage" the sea otter so as to avoid "resource 

 conflicts" prompted Dr. John H. Phillips, director of Hopkins Marine 

 Station of Stanford University, to testify that this California Senate 

 bill presents a simplistic answer to the abalone decline by using the 

 otter as a scapegoat. He further testified that legislation is needed to 

 increase chances for survival of otters, as well as our declining abalone 

 industry. 



Karl Kenyon has reported more than 40 food species from the 

 stomachs of Amchitkan sea otters,^ and I have observed southern sea 

 otters eat more than 25 different species. The red and black abalone are 

 but two of these. Abalones and spiny lobsters are disappearing in south- 

 ern California and among the Channel Islands, where no sea otters 

 exist. The excessive human take appears to be causing the decline in 

 these fisheries. 



If the sea otter can survive an environment which is becoming in- 

 creasingly polluted, it may eventually extend its range. Should it re- 

 occupy its former haunts in southern California, it would improve our 



1 Martin, J. H. and G. A. Knauer, Cd. Cr, Cu, and Zn concentrations in tlie southern 

 se.a otter. Manuscriot in preparation. 



2 Martin, J. H., G. A. Knauer, and B. H. Robison. Mercury in the pelagic food web. 

 Manuscript in preparation. 



3 Vandevere, J. E. Feeding behavior of the southern sea otter. Proc. Sixth Ann. Conf. 

 on Biol. Sonar and Diving Mammals, Menlo Park, Calif.. Stanford Research Institute. 

 p. 87-94. 1969. 



* Kenyon. K. W.. 1969. The sea otter in the Eastern Pacific Ocean. North American 

 Fauna. Number 68. Bureau of Sport Fisheries and Wildlife, U.S. Government Printing 

 Office, Washington, D.C. 20402. p. 117. 



