Lowry and Forney: Abundance and distribution of Zalophus califormanus 



337 



70 

 60 

 50 

 40 

 30 

 20 

 10 



, Sightings V~\ % Km surveyed 



17 sightings 

 612 km surveyed 



tki 



i 



f-L-H 



_ 



40 



30 



-20 



10 



0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-69 90-99 100-109110-120 



y 70 



60 - 



50 

 40 

 30 

 20 

 10 



| % Sightings ^]% Km surveyed 



40 sightings 

 2,181 km surveyed 



40 



-30 



-20 



-10 



_n 







70 

 60 



50 i 

 40 

 30 

 20 

 10 

 



B 



70 



60 



50 



40- 



30 



20 



10 







Sightings f~J % Km surveyed 



67 sightings 



1 ,796 km surveyed 



\M 



0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 



40 



30 



20 



10 



90-99 100-109110-120 



D 



, Sightings [~J % Km surveyed 



18 sightings 

 888 km surveyed 



_Q 



t— =H h 



-+- 



40 2. 



30 



-20 



10 



0-9 '10-19 20-29 30-39 40-49 50-59 '60-69 70-79 '80-69 90-99 100-109110-120 ' ~ "0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 60-89 90-99 100-109110-120 



Distance from shore (km) 



Figure 5 



Distances from shore for California sea lions (Zalophus californianus) sighted and kilometers from shore for California 

 sea lions that were surveyed during strip transect surveys in Beaufort sea state 0-4 and 0-49% glare conditions. (A) 

 26-30 May 1998, (B) 12-28 September 1998, (C) 1-11 December 1998, and (Di 13-21 July 1999. 



Haulout abundance 



In 1998 and 1999, aerial photographic surveys of sea 

 lion haulouts in central and northern California were 

 conducted during 31 May-8 June 1998, 7-18 July 1998, 

 11-20 September 1998, 14-16 December 1998, and 6-11 

 July 1999. For the July 1998 survey, low clouds pre- 

 vented aerial surveys of the coastline from Point Sal 

 (34°54.1'N, 120°40.0'W) to Point Conception (counts 

 from 1999 were used for these areas) and from the 

 Klamath River (41°32.5'N, 124°04.7'W) to Humboldt 

 Bay (40°45.4'N, 124°14.4'W). To estimate abundance 

 in the latter missed area, we obtained ground counts 

 from the mainland at all haulouts except Turtle Rocks 

 <41°08.0'N, 124°10.9'W) and Redding Rock (41°20.6'N, 

 124°10.5'W). In July 1999 a low cloud layer prevented 

 surveys of the coastline between Golden Gate Bridge 

 (37°51.1'N, 122 34.0'W) and just north of Ano Nuevo 

 Island (37°06'N, 122 20'W). This gap should have had 

 virtually no effect on the total counts, however, because 

 there is only one minor haulout in this region. 



The number of sea lions hauled-out in the study area 

 (Table 2) were 36,576 (May 1998), 26,260 (includes 

 estimate, July 1998), 35,512 (September 1998), 32,055 

 (December 1998), and 13,559 (July 1999). There was 

 no significant difference in total number of sea lions 

 between the seven zones (P= 0.229) and between sea- 

 sons (P=0.179; Table 3). More sea lions were counted 

 in 1998-99 than during previous surveys in 1980-82 

 and 1995-96 (P<0.003 for both tests), but no difference 

 in counts was found between 1980-82 and 1995-96 

 surveys (P=0.232; Table 3). 



In 1998, the greatest numbers of sea lions were found 

 in zone D and E (Table 2), corresponding to the San Fran- 

 cisco and Monterey Bay regions; most animals hauled out 

 at Ano Nuevo Island and South Farallon Islands. Juve- 

 niles and adult-females or young-males were the most 

 prevalent age and sex classes found in the study area in 

 1998 (Table 2). More adult males were counted during 

 the May-June 1998 survey than during other surveys. In 

 1998 the number of pups in the study area ranged from 

 22 (December 1998) to 149 (May- June 1998). 



