Barlow and Forney: Abundance and population density of cetaceans m the California Current ecosystem 



521 



Table 6 



Total numbers of sightings (n), estimated cetacean abundance (N), and density per 1000 km^ within the entire study area. Data 

 from 1991 to 2005 were pooled within geographic regions, and estimates of abundance for each region were summed to give total 

 abundance. Coefficients of variation iCVi apply to both abundance and density estimates. CVs and 95"^*^ confidence intervals (CI) 

 were based on a bootstrap calculation. Variances were assumed to be additive in estimating the CVs of the subtotals and totals. 

 Unidentified large whales and small whales were not sufficiently specified to be included in the subtotals. 



Species 



Abundance 



CV(N\ 



Short-beaked common dolphin 

 Long-beaked common dolphin 

 Unclassified common dolphin 

 Striped dolphin 

 Pacific white-sided dolphin 

 Northern right whale dolphin 

 Bottlenose dolphin (offshore) 

 Risso's dolphin 

 Short-finned pilot whale 

 Killer whale 

 Dall's porpoise 

 Mesoplodon spp. 

 Cuvier's beaked whale 

 Baird's beaked whale 

 Kogia spp. 

 Sperm whale 

 Minke whale 

 Bryde's whale 

 Sei whale 



Sei or Bryde's whale 

 Fin whale 

 Blue whale 

 Humpback whale 

 Unidentified delphinoid 

 Unidentified ziphiid whale 

 L'nidentified small whale 

 Unidentified roqual whale 

 Unidentified large whale 

 Subtotal: Delphinoids 

 Subtotal: Ziphiidae 

 Subtotal: Physeteridae 

 Subtotal: Balaenopteridae 

 Total 



Dall's porpoise abundance was inversely related to sea 

 surface temperature. 



Balaenopteridae The common baleen whales in Cali- 

 fornia waters were blue, fin, and humpback whales. The 

 abundance of these species was consistently high during 

 the summer and fall study period. Our estimates of 

 humpback whale abundance increased from 1991 to 1996 

 and decreased slightly in 2001 and 2005; however, hump- 

 back whales were observed to be highly concentrated in 



productive nearshore waters off California and northern 

 Washington during 2005 that were not well sampled 

 during our surveys. A more comprehensive and precise 

 abundance estimate of 1769 humpback whales (CV=0.16) 

 was obtained when additional survey effort was included 

 within these areas (Forney, 2007). More precise esti- 

 mates from mark-recapture studies also indicate an 

 increase in abundance from 1991 to 1997 (Calamboki- 

 dis and Barlow, 2004), a decrease in 1999-2000 and in 

 2000-2001, and a subsequent increase to about 1400 



