Barlow: Abundance of cetaceans in California waters ship surveys 



mates (Dohl et al., 1986; Barlow, 1988; Calambokidis 

 et al., 1990a; Dohl et al. 23 ). This is the first cetacean 

 survey in California waters to include the region 

 between 277 and 555 km (150-300 nmi) offshore. The 

 studies of Dohl et al. 2 - 3 included only the inshore 185 

 km (100 nmi) of the present study area, making di- 

 rect abundance comparisons difficult. The mark-re- 

 capture population estimates of blue and humpback 

 whales by Calambokidis et al. (1990, a and b) were 

 based on individuals sighted near the coast. Further- 

 more, the estimates of Dohl et al. 2 - 3 do not have as- 

 sociated statistical confidence intervals. Hence, ac- 

 curate comparisons with previous studies can be 

 made only for the more coastal species and mean- 

 ingful statistical tests of differences can be made for 

 even fewer species. Direct comparisons with the 1991 



and 1992 aerial surveys (Forney et al., this issue) 

 are planned for future publications. 



The abundance of harbor porpoise estimated for 

 1984 and 1985 was approximately 9,576 (CV=0.51) 

 (Barlow [1988] his regions 1-4), which is smaller than 

 the present estimate of 52,700 (CV=0.68). This dis- 

 crepancy may be due to the inappropriate design of 

 the present survey for a coastal species such as har- 

 bor porpoise. 



Humpback whale abundance in central California 

 was estimated as 338 based on aerial surveys from Au- 

 gust to November of 1980-83 (Dohl et al. 3 ); however, 

 this estimate does not include a correction factor for 

 submerged whales. Based on mark-recapture methods, 

 the abundance of humpback whales in 1991 and 1992 

 was estimated to be 581 (CV=0.03). 1 This estimate is 



