Surface water temperatures in Unimak Pass 

 changed from about 5°C. in May to 5° -8° C. 

 in June, 7O-8OC. in July, 7° -90C. in August 

 and September, and 7°-8°C. in October, At 

 the same time surface water temperatures 

 increased on the Pacific side from 6° to 9°C. 

 in June to 10° to 13° C. in August and Septem- 

 ber. In the Bering Sea, surface water tem- 

 peratures increased from 7° to 8°C. in June 

 to 8° to 12° C. in July, August, and September, 

 although the average temperature in the area 

 adjacent to Unimak Pass was 8°-9°C. 



surface. They jump out of the water or roll at 

 the surface to breath and submerge imme- 

 diately. If pursued, they usually move in one 

 direction. Because of the short length of time 

 spent at the surface, they are difficult to ob- 

 serve unless the sea is calm and favorable 

 light exists. Traveling seals are more in 

 evidence during May, June, and early July 

 than in later months. There is some evidence 

 to suggest that they stop to rest after moving 

 through the pass and reaching an area outside 

 the influence of strong currents. 



Fur seals are believed to use most of the 

 passes and straits in the Aleutian Islands in 

 making their way to and from the Bering Sea 

 and the Pacific Ocean; however, it is likely 

 that many of the seals that winter in the eastern 

 North Pacific use Unimak Pass. There are 

 several reasons why this pass might be favored 

 over others. Unimak Pass is the widest in the 

 area and has a relatively weak current. Fur 

 seals appeared to have little difficulty going 

 through Unimak Pass against the current. It is 

 also the shortest route (except False Pass 

 which apparently is seldom used by fur seals) 

 from the eastern Pacific to the Pribilof Islands. 

 Abundant food is present in the pass and its 

 approaches. 



In this area the three other entrances to 

 the Bering Sea are Akun Strait, Akutan Pass, 

 and Unalga Pass, which are relatively small 

 and have average current velocities about 

 double that in Unimak Pass. Maximum velo- 

 cities of 9 knots in Unalga Pass and 12 knots 

 in Akun Strait have been reported. 



Small numbers of fur seals were observed 

 in Akutan Pass and Akun Strait in 1962. Hugh 

 McGlashon, trader and longtime resident at 

 Akutan, reported that he had observed fur 

 seals on at least one occasion in years past 

 off Akun Strait on the Pacific side. On the 

 change of tide, according to his statement, they 

 went through the Strait in a relatively compact 

 group which dispersed after passing into 

 Akutan Bay on the Bering Sea side of the 

 Strait. 



Fur seals in Unimak Pass appear to be 

 traveling, feeding, or temporarily resident. 

 Traveling seals seldom spend much time at the 



Feeding seals concentrate in areas of 

 abundant feed. When actively feeding, they roll 

 at the surface to breath and return imme- 

 diately to feed. If feeding in a school of fish 

 at or near the surface they appear at the surface 

 frequently. In a calm sea they are easy to 

 locate. If a large fish is caught, the seal sur- 

 faces to eat it, but when feeding on small 

 schooling fish and squids, the seal does not 

 need to surface. After feeding they rest or 

 sleep at the surface. At this time they are 

 lethargic and easy to approach. Some seals 

 can be approached almost to within touching 

 distance before they awaken. From late July 

 to early October, many feeding seals were 

 present in the northern approaches and in 

 the north and central parts of Unimak Pass. 

 They were primarily adult females ranging 

 southeastward from the Pribilof Islands. 



A few immature fur seals seen in Unimak 

 Pass and vicinity were believed to be resident 

 throughout most of the study period. Some 

 could usually be found even when traveling 

 and feeding animals were not present. 



During May, June, and July, a principal 

 feeding area was centered approximately 20 

 miles southeast of Tigalda Island. The main 

 food of seals here was a squid, Gonatus magis- 

 ter. Two lesser food species were Mallotus 

 villosus (capelin) and Ammodytes hexaptems (sand 

 lance). 



Another feeding ground was located in the 

 northern approach to Unimak Pass north and 

 northeast of Akun Island. This was frequented 

 during July, August, September, and October. 

 Seals moving northward probably feed in this 

 locality after coming through Unimak Pass. 



11 



