THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 265 



Amchitka's shores well ahead of an atmospheric storm. Then they 

 may continue to break violently along the exposed coast for many 

 hours after the storm has passed. In addition, waves created by 

 storms that fail to reach Amchitka, may break on the Pacific coast 

 of the island. Heavy or violent wave action along the Pacific 

 coast was recorded on 43 days during the study period, but similar 

 conditions prevailed on only 12 days along the Bering Sea coast 

 (figs. 103 and 104). 



The data indicate that the amount of mortality that occurred 

 in 1962 at Amchitka was related primarily to population size and 

 available habitat. Even though the storm wave action along the 

 Pacific coast was more intense than along the Bering Sea coast, 

 the threshold of stresses sufl[icient to precipitate mortality was 



z 



° HEAVY 



PACIFIC 



OCEAN 







SURF CONDITION /"l/^/ \ A \\ 





















20 25 

 JAN. 



5 



FEB. 



5 10 15 20 25 30 

 MAR 



Figure 103. — Daily record of surf conditions and of otters found dead on 

 the Pacific Ocean coast of Amchitka from 14 January through 30 April 

 1962. Partly because ground swells travel long distances in the deep 

 Pacific Ocean, wave activity on that coast is more intense than on the 

 Bering Sea coast (see fig. 104). 



Figure 104. — Daily record of observed surf condition and otters found dead 

 on the Bering Sea coast of Amchitka Island from 19 January through 

 30 March 1962. Surf conditions are more moderate on the Bering Sea 

 coast than on the Pacific coast because in this relatively shallow sea ground 

 swells do not travel ahead of storms and wave action attenuates soon 

 after the passing of wind storms (see also fig. 103). 



