Zwolinski et al. : Distributions and abundances of Sardinops sagax and other pelagic fishes in the California Current Ecosystem 
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Figure 6 
Biomasses (million metric tons; Mt) of the most abundant epipelagic coastal pelagic fish 
species (CPS) in the California Current Ecosystem (CCE), estimated by the acoustic-trawl 
method, in spring 2006, 2008, and 2010 (this study), and summer 2008 (Demer et al., 2012). 
The 95% confidence intervals (CI 95 ) are indicated. Superimposed are the estimates of total 
sardine ( Sardinops sagax) biomass from the 2010 assessment (Hill et al., 2010) and the 
spawning stock biomass (SSB) estimated from the daily egg production method (DEPM; Lo 
et al., 2010). The biomass estimates from the Pacific mackerel (Scomber japonicus) assess- 
ment were not included because the distribution of that stock greatly exceeds the sampling 
area, and estimates for the relevant subpopulation were not available (Crone et al., 2009). 
of the stock. From 2006 to 2008, the abundance of 
jack mackerel appears to have remained constant or 
increased slightly (Fig. 6). Either the population was 
stable and entirely contained within the acoustic- 
trawl survey area, or, less likely, a variable portion of 
the population within the survey area comprised the 
same biomass. 
Pacific mackerel comprised only a small fraction of 
the CPS biomass. Their abundances were typically less 
than 50,000 metric tons (t), which is roughly one-sixth 
of the total stock biomass estimated by the assessment 
(>280,000 t; Crone et ah, 2009). The large discrepancy 
between the two estimates is likely a consequence of 
the stock residing mostly south of the survey area, as 
far as Cabo San Lucas (Crone et al., 2009). Thus, the 
acoustic-trawl estimates of Pacific mackerel biomass off 
the U.S. west coast represents a variable and unknown 
portion of the entire stock. The high CV values are 
indicative of high patchiness and could be improved 
by increasing sampling effort. To reduce the variable 
systematic error, the survey area should be extended 
farther south, and also more nearshore, particularly 
off southern California (Crone et al., 2009; Moser et 
al., 2001). 
Anchovy is currently a monitored species with a re- 
sidual fishery and unknown abundance (PFMC, 2009). 
They were caught in a few trawls in each survey, no- 
tably off southern California where they were once the 
most abundant CPS (Mais, 1974; Mason, 2004). An- 
chovy were also caught, somewhat consistently, close 
to shore off the Columbia River mouth and Monterey 
Bay, indicating a higher geographical affinity compared 
with the other CPS. Improved knowledge of the anchovy 
stocks will require increased and directed effort in the 
locations of higher expected abundances. 
For all the CPS species combined, the current data do 
not clearly indicate a relationship between the number 
and locations of trawls or transects, and the precision 
of the survey estimates. Therefore, the optimization of 
future surveys for a desired sampling precision will 
