FISHERY BULLETIN: VOL. 85, NO. 2 



60 r 

 50 



40 



30 



20 

 10 



- Central Gulf of Alaska 



Count = 36,016 - 347.7 (year - 1955) 

 r^ = 0.924 

 p <0.05 



Central Aleutian Islands 



Count = 27,340 + 170.6 (year - 1955) 



p>0.05 



10 







Western Gulf of Alaska 



Count = 24,385 - 653.8 (year - 1955) 

 r^ =0.971 

 p< 0.05 



J I 



'2 =0.068 



Eastern Aleutian Islands 



Count = 57,716 - 1701.2 (year - 1955) 



r^ = 0.973 



p<0.01 



A 



J I I I I 



1956 61 66 71 76 81 85 



1956 61 66 71 76 81 85 



Year 



Figure 2.— Trends in total adult and juvenile northern sea lion abundance by area in Alaska, for spring and summer surveys conducted 



from 1956 to 1985. 



empty. Although some rookeries have been reduced 

 in size and decreases have been observed in all age 

 and sex groups, the ratio of adult females to terri- 

 torial males has remained relatively constant be- 

 tween 1977-78 (14.4-17.3) and 1986 (16.4). Between 

 1985 and 1986, however, the number of adult males 

 remained constant, while the number of females 

 decreased by 26%. 



Island totals of juveniles were similar in 1985 (87 

 animals) and in 1986 (110 animals). However, an 

 analysis of comparable areas of the island (i.e., 

 N1-N3 and A2-A4; Fiscusi^) indicated that the 

 juvenile portion of the population had decreased 

 significantly (x^ = 4.09, P < 0.05) from 9.0% in 



1977 to 1.4-1.6% in 1985-86. A comparably low rate 

 (2%) has only been observed at Ano Nuevo Island 

 (Gentry 1970) and that rate was calculated for a 

 single primary rookery rather than a whole island. 

 Rates such as the 22% observed at Marmot Island 

 in 1983 or the 25% observed for British Columbia 

 in 1956 seem more typical for northern sea lion rook- 

 eries (Pike and Maxwell 1958; Merrick 1984). 

 Counts of pups were available for six rookeries 



'^Fiscus, C. H. 1970. Steller sea lions at Ugamak Island, Aleu- 

 tian Islands, Alaska, June 1969. Unpubl. Rep., U.S. Fish Wildl. 

 Serv., Bur. Commer. Fish., Mar. Mammal Biol. Lab., Seattle, 78 

 p. Northwest and Alaska Fish. Cent. Natl. Mar. Mammal Lab., 

 NMFS, NOAA, 7600 Sand Point Way N.E., Seattle, WA 98115. 



358 



