THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 283 



dead on beaches exhibited malocclusion of the postcanine teeth. 

 In juveniles this condition resulted when deciduous teeth were 

 being replaced by permanent teeth. In adults malocclusion resulted 

 from severe tooth attrition which may have been caused by chew- 

 ing hard-shelled invertebrates. 



8. Prolonged storm conditions precipitated mortality but the 

 amount of mortality was found, in 1962, to be related to the avail- 

 able feeding habitat and population density. 



9. The relative intensity of storm wave action was greater on 

 the Pacific Ocean coast than on the Bering Sea coast, but the mor- 

 tality on each coast was proportional to population density and not 

 to relative intensity of storm conditions, indicating that the thres- 

 hold of conditions causing mortality was passed on both coasts. 



10. The annual mortality of the Amchitka population was esti- 

 mated in 1959 and 1962 to be about 8 to 11 percent. Two methods 

 of estimating mortality gave similar results. 



11. In the Shumagin and Sanak Islands areas, where the sea 

 otter population was about four and two otters per square mile of 

 water less than 30 fathoms deep, respectively, no evidence was 

 found to indicate unusual mortality in the late-winter and early- 

 spring storm periods. 



12. The Amchitka population was about 19 otters per square 

 mile of water less than 30 fathoms deep and had overexploited 

 certain food resources. Because of this fact, the population was 

 restricted by relatively high mortality which resulted primarily 

 from malnutrition and was precipitated by environmental stresses 

 during late-winter, early-spring storms. 



13. Sea otters are infested by a variety of internal parasites 

 but these rarely appear to be the direct cause of significant mor- 

 tality. External parasites are limited to fortuitous infestations 

 of nasal mites. Such infestation is unusual in wild otters. 



14. The most frequently observed condition at death was 

 emaciation accompanied by hemorrhagic enteritis. Chronic disease 

 conditions and bodily injuries were observed. 



15. Sharks, the Bald Eagle, and killer whale are known to kill 

 sea otters. Predation, however, is probably an insignificant source 

 of mortality. 



16. Environmental pollution in areas now heavily utilized by 

 man will probably prevent the sea otter from reoccupying all of 

 its former range. 



17. No evidence is available to indicate significant illegal kill- 

 ing by man of sea otters in Alaska. In California, however, illegal 

 killing by man may, today, hinder the increase of the sea otter 

 population. 



