FISHERY BULLETIN: VOL. 85. NO. 2 



STUDY REGION AND METHODS 



Study Region 



The study included northern sea lion hauling sites 

 in southwestern Alaska from Kiska Island in the 

 Aleutian Island chain eastward to the Barren 

 Islands in the central Gulf of Alaska (Fig. 1). This 

 region was subdivided for analysis into four areas: 

 1) central Gulf of Alaska, 2) western Gulf of Alaska, 

 3) eastern Aleutian Islands, and 4) central Aleutian 

 Islands. 



Two general types of northern sea lion sites on 

 land were recognized— rookeries and haul-outs 

 (Loughlin et al. 1984). Rookeries were areas where 

 adult males actively defended territories and most 

 females gave birth and mated. Haul-outs were sites 

 where few pups were present and where little 

 breeding took place. Some islands included more 



than one distinct rookery and haul-out. A total of 

 114 sites, of which 28 were rookeries (on 27 islands), 

 were surveyed during 1984-86. 



Ugamak Island was a site for NMML field studies 

 during the northern sea lion breeding seasons in 

 1969, 1977, 1978, 1985, and 1986. The island is 

 located in the eastern Aleutian Islands (long. 

 164°50'W, lat. 54°14'N), about 110 km east of Dutch 

 Harbor, AK. The island contained the largest aggre- 

 gation of breeding sea lions in the Aleutian Islands 

 as late as 1969. 



Survey Methods 



Aerial photographic surveys of northern sea lion 

 rookeries and haul-outs in the eastern Aleutian 

 Islands area (Fig. 1) were conducted 7-12 July 1984, 

 using a Bell 205*^ helicopter flown off of the NOAA 

 ship Surveyor. A survey of the entire study region 



1 Central 

  Gulf of 

 Alaska 



4 Central 

 Aleutian 

 Islands 



3 Eastern 

 Aleutian 

 Islands 



O Western 

 Gulf of 

 Alaska 



Figure 1.— The four Alaskan study areas 

 (left) and 28 northern sea lion rookery sites 

 (right) counted during 1984-86. Rookery 

 island name and number as in Table 2. 



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