206 
Fishery Bulletin 112(2-3) 
A 
124°W 123°W 122°W 121°W 120°W 119'W 118°W 117°W 
B 
124°W 123"W 122°W 121°W 12CTW 119”W 118“W 117°W 
c 
124°W 123°W 122°W 121“W 120°W 119°W 118°W 117°W 
D 
124°W 123°W 122°W 121°W 120°W 119°W 118”W 117°W 
PACIFIC OCEAN 
N 
A 
* 
i 1 
0 100 km 
> 
Santa Barbara 
Los Angeles 
0 % * 
V 
* 
San 
Diego 
n V-X \x 
Study area zones 
167,087 km 2 Deep (>=2000 5 m) 
71,407 km 2 Shallow (<2000.5 m) 
— 2000-m line 

Figure 3 
Maps of on-effort sightings of the 4 most commonly encountered species of large whales, the (A) humpback whale (Mega- 
ptera novaeangliae ), (B) blue whale ( Balaenoptera musculus), (C) fin whale (B. physalus), and (D) sperm whale ( Physeter 
macrocephalus), recorded during the 16 shipboard line-transect surveys conducted quarterly during 2004-08 as part of 
the California Cooperative Oceanic Fisheries Investigation. 
from analyses because the encounter records likely rep- 
resent extralimital occurrences for both species. 
Abundance estimates from line-transect data 
Significant covariates for estimation of detection func- 
tions varied by species and species group (Table 2). On 
the basis of AIC values and visual examinations of test 
models, we selected sea state as a significant covariate 
for both the delphinid and Dali’s porpoise group. Addi- 
tionally, group size and dolphin species were chosen for 
the delphinid detection model. Average effective strip 
width (ESW) was 1294 m for large whales, 298 m for 
delphinids, and 305 m for porpoises. 
Baleen whales We encountered 6 or possibly 7 species 
of baleen whales (one encounter was undetermined; 
it was not possible to distinguish whether it was a 
Bryde’s or sei whale [ Balaenoptera edeni brydei, B. e. 
edeni, or B. borealis]), and sample sizes by species were 
sufficient to calculate seasonal abundance and density 
estimates for 3 of those species. Fin whales had the 
