188 
Fishery Bulletin 108(2) 
120000- 
+ July 2003 + 
O July 2004 
Number of oocytes 
"vl 
o 
o 
o 
o 
i i 1 1 i i 
+ 0 o 
. 0+ « + + 
+ +0 
+ + + + 
+ 
20000 - 
o 
I 1 1 1 1 1 1 1 1 1 1 1 
100 200 300 
Body weight (gm without ovary) 
Figure 8 
Batch fecundity ( F b ), the estimated number of hydrated or migra- 
tory-nucleus oocytes, of Pacific sardine ( Sardinops sagax) as a 
function of ovary-free fish weight (WJ. Pacific sardine females were 
collected from trawl samples off Oregon and Washington during July 
2003 and 2004. Equation for regression line is F 6 = 295.83W 0 ^. 
spawning characteristics during these two periods. The 
spawning habitats of sardine off the PNW in 2003 and 
2004 were similar, whereas the spawning habitats off 
California were quite different: concentrated off central 
California in 2004 and distributed through the whole 
survey area in 2005. Note, no eggs were caught during 
the July California Cooperative Oceanic Fisheries Inves- 
tigations (CalCOFI) surveys off California in either 
CalVET or bongo net tows. 
The daily egg production off the PNW was low in 
both 2003 and 2004 (0.04 and 0.037eggs produced/0.05 
m 2 /day, respectively), lower than that in 1994 (0.50 
eggs produced/0.05 m 2 /day) (Bentley et al., 1996), and 
lower than those off California (1.52 and 0.96 eggs 
produced /0.05 m 2 /day) in 2003, 2004, and other years. 
This low egg production in the PNW contributed only 
1.8% of the total U.S. west coast egg production in 
2003-04. The low PNW egg production estimates could 
be the result of the July surveys occurring after the 
spawning peak, possibly in June, as the SST was high 
(Emmett et al., 2005), or the result of the egg mortal- 
ity of Pacific sardine off the PNW being different from 
that off California, or both. Future ichthyoplankton 
surveys with large sample sizes are needed to obtain 
direct estimates of the daily egg production and egg 
mortality off the PNW. 
The egg production estimates from July 2003 and 
2004 were very similar even though the relative 
abundances were quite different. With similar egg 
production in two years, one might expect that the 
biomass of recruits would be similar. However, the 
2003 year class was much stronger than that of 2004. 
This difference would be most likely due to the more 
favorable environmental conditions in 2003 than in 
2004. 
One interesting question to ask is what effect a 
reduction of the spawning habitat or egg production 
would have on the PNW Pacific sardine population. The 
sustainability of the Pacific sardine population off the 
PNW depends greatly on the Pacific sardine population 
off California, oceanographic conditions, and food avail- 
ability (MacFarlane et al., 2005) because most of the 
spawners (>190 mm SL) off the PNW in the summer 
are migrants from California. As long as the Pacific 
sardine population off California is large enough to al- 
low adequate migration to the PNW in the summer to 
spawn, the population off the PNW will be sustained. 
Of course, if environmental conditions are unfavorable, 
the proportion of spawners may be reduced, affecting 
both the recruits to the local population and the size 
of the population in the following spring. If the popu- 
lation off California decreases to the level of collapse, 
the population off the PNW may have been diminished 
well before the collapse off California. This status of the 
PNW population was evident from the history of land- 
ings in the last Pacific sardine collapse (Fig. 1). Dur- 
ing the waning years of sardine population, the PNW 
commercial landings ended in 1949, 16 years before the 
California catch ended in 1965. The sardine population 
began recovering in the late 1970s-early 1980s off Cali- 
fornia. Incidental landings off California began in 1981, 
11 years before an incidental catch of sardine off the 
PNW in 1992 due to the favorable El Nino conditions, 
and 17 years before directed landings in 1998. 
Application of proper management strategies to pre- 
serve the population off California, and thus the mi- 
