182 
Fishery Bulletin 108(2) 
The 2 value was the estimate from the daily egg pro- 
duction method (DEPM) surveys off California in 2003 
(0.48 [CV=0.08]) and 2004 (0.25 [CV=0.04]) (Lo et ah, 
2005) because of the lack of sufficient data to estimate 
2 off the PNW. Age at hatching (in days) was 2.5 days 
computed from the temperature-dependent sardine 
egg development model for stage XII given in Lo et al. 
(1996): ^ = 30.65* exp(-0.145*temp-0.037*12)*12 1 41 /24, 
where temp is the average temperature from positive 
CUFES collections during the July surveys, and equals 
16.4°C and 16.3°C for 2003 and 2004, respectively. This 
integral estimate is biased upward on the basis of a com- 
parison of P 0 j and the P 0 from the nonlinear regression 
from four California daily egg production surveys and 
a simple theoretical population. Both cases indicated 
that the relative bias (rb = ( P 0I — P 0 )/ P 0I ) was close 
to 20% of P 0 j Thus the bias-corrected egg production 
(P o, f ) would be P 0c =P 0I (l-rb)=_P 0 7 (0.8). 
The mean density of eggs (Y-) (eggs/0.05 m 2 ) was 
estimated for each of two strata (i=l,2), with 125°W 
latitude as the dividing line. 
The overall mean density (Y) 
for the whole survey area was a 
weighted average with the area 
in each stratum as the weight 
and was used to estimate the 
daily egg production. No esti- 
mate of egg production for each 
stratum was obtained because 
of the small sample sizes. 
To understand the relative 
contribution of egg production 
from the PNW area, we com- 
puted a ratio of the total egg 
production in the PNW to the 
total egg production in the 
whole area (PNW and Califor- 
nia) as P 0 j Aj/^P 0 j Aj , where 
P 0 ■ is the daily egg production 
during the peak spawning time 
in the survey area Ay, j = 1 re- 
fers to the PNW area in July 
and j - 2 refers to California in 
April. 
Adult reproductive state 
and parameters 
For all four surveys, we used 
histological analysis of all ovar- 
ian tissues, along with trawl and 
female data, to provide accurate 
assessment of adult parameters 
and reproductive state such as 
maturity, spawning period, 
recent spawning activity, post- 
spawning condition, or iden- 
tification of advanced oocyte 
development for a selection of 
females for batch fecundity esti- 
mation. In the laboratory, each 
preserved ovary was blotted and 
weighed to the nearest mg. A 
piece of each ovary was removed, 
a histological slide was pre- 
pared, and the tissue sections 
were stained with hematoxylin 
and eosin. We analyzed oocyte 
development, atresia, and post- 
ovulatory follicle age to assign 
Washington-Oregon 
California 
-p 
03 
0.35 
0.30 
0 25 
0.20 
0 15 
0.10 
0.05 
0.00 
March 2004 
-M- 
0.35 
0 30 
0.25 
0.20 
0 15 
0.10 
0.05 
0.00 
March-April 2004 
80 100 120 140 160 180 200 220 240 260 280 
80 100 120 140 160 180 200 220 240 260 280 
80 100 120 140 160 180 200 220 240 260 280 
Standard length class (mm) 
Figure 6 
Length frequency distribution of Pacific sardine ( Sardinops sagax) off Washington 
and Oregon, and California during 2003, 2004, and 2005 from fishery independent 
trawl surveys (black bars) and port sampling of commercial purse seine catches 
(gray bars). Catch data were provided by California Dept, of Fish and Game, Oregon 
Dept, of Fish and Wildlife, and Washington Dept, of Fish and Wildlife. 
