Henderson et al.: Effects of sea-surface temperature on the occurrence of small cetaceans off Southern California 
167 
A 
B 
C 
Slope 
m 
<D 
Q 
Slope 
CL 
<D 
Q 
Depth Max 
Depth Max 
Depth Mean 
ENSO 
to 
I 
in 
ra 
o 
w 
12 
SeasAv 
16 18 
SeasAv 
20 
SeasAv 
-1 0 -0 5 00 0 5 
PDO 
10 15 
Spr Sum Aut 
Quarter 
Win 
Spr Sum lAut Win 
Quarter 
w 
5 
ra 
ra 
CL 
CO 
o 
If 
Q 
O 
O 
CalCOFb Ca ICO Fib SWFSC 
SurveyType 
Figure 4 
Generalized additive model functions of sightings per unit of survey effort in 
Southern California waters for (A) the combined category of both the short- 
beaked common dolphin and long-beaked common dolphin (. Delphinus sp.) from 
1979 to 2009, (B) short-beaked common dolphin ( Delphinus delphis), and (C) 
long-beaked common dolphin ( D . capensis) during cruises conducted by the 
NOAA Southwest Fisheries Science Center (SWFSC) from 1991 to 2005 and 
by the California Cooperative Oceanic Fisheries Investigations (CalCOFI) from 
2004 to 2009. Estimated degrees of freedom of the smooth function are given 
(in parentheses on they-axis) for all included variables from the best-fit model. 
Solid lines represent the marginal effect of the given variable after controlling 
for the other variables in the model. The shaded band represents 2 standard 
errors. SurveyType is the variable for the cruises: SWFSC, CalCOFIa ( 1979 — 
2004) and CalCOFIb (2004-09). Variable abbreviations: DepthMin=minimum 
depth (m), DepthMean=mean depth (m), MaxDepth=maximum depth (m), 
SeasAv=seasonal averaged sea-surface temperature (°C), ENSO=El Nino- 
Southern Oscillation, and PDO=Pacific Decadal Oscillation. 
