158 NORTH AMERICAN FAUNA 68 



scouting flights around Semisopochnoi Island and report that they 

 have never seen sea otters in that vicinity." 



On the aerial survey of 19 May 1959, v^hen observation condi- 

 tions v^ere excellent, we saw 393 otters (16 per square mile of 

 habitat) at Semisopochnoi Island. It thus appears that the animals 

 moved from Amchitka across nearly 30 miles of open water to 

 this island after 1943, when the Amchitka population approached 

 maximum size and population pressure stimulated emigration. 

 By 1965, the population at Semisopochnoi had decreased to an 

 estimated 8 otters per square mile of habitat (table 21). 



Delarof Islands 



This small group (fig. 75) is technically part of the Andreanof 

 group (U.S. Board on Geographic Names, 1963), but is treated 

 as a separate unit here. The group includes a distance of about 

 33 miles from east to west and is separated from Tanaga Island 



i~ 1 i 



Delarof Islands Tanaga- - 1, 059 



Amatignak - - 70 



I'o M'-, 178° 

 I 



Figure 75. — The Delarof Islands of the western Andreanof Islands were 

 apparently among the few Aleutian areas where the sea otter remained in 

 1911 when it was given protection. A large population developed here and 

 at Kanaga and Tanaga Islands by the late 1940's, but population pressure 

 did not cause repopulation of nearby Adak until the mid-1950's. The number 

 of otters observed on aerial surveys of 2 and 3 May 1965, as shown on this 

 map, was 2,790. 



