436 
Fishery Bulletin 1 10(4) 
Year and date 
□ 
□ 
Juvenile salmon 
American shad 
Northern anchovy 
Pacific herring 
Surf smelt 
Shiner perch 
Stickleback 
Other 
Figure 2 
(A) Box plots of log-transformed density (number/m 2 ) and (B) percent composition of dominant 
fish species caught by cruise during spring of 2007-10. These species include American shad 
(Alosa sapidissima), northern anchovy ( Engraulis mordax ), Pacific herring ( Clupea pallasii), 
surf smelt ( Hypomesus pretiosus), shiner perch ( Cymatogaster aggregata ), and threespine 
stickleback ( Gasterosteus aculeatus ). The category of juvenile salmon includes all species- 
and-age classes of juvenile salmon combined: yearling and subyearling Chinook salmon 
(Oncorhynchus tshawytscha ), coho salmon (O. kisutch), chum salmon (O. keta ), sockeye salmon 
(O. gorbuscha ), and steelhead (O. mykiss). The box plots illustrate 25 th and 75 th percentiles 
(lower and upper edges of box, respectively), the median (line within the box), 10 th and 90 th 
percentiles (whiskers [error bars] below and above the box, only on cruises when n>9), and 
dots indicate outliers (< 10 th or >9Q th percentiles). 
mid-April, when sampling began, catches of all juve- 
nile salmon were extremely low (CPUE<1/1000 m 2 ). 
As the spring progressed, the abundances of juvenile 
salmon increased. Maximum abundances occurred in 
mid-May for yearling Chinook and coho salmon and 
steelhead, a somewhat earlier peak in abundance 
occurred in early May for chum salmon, later peaks in 
abundance occurred in early June for sockeye salmon, 
and late June or early July for subyearling Chinook 
salmon. Consequently, when sampling stopped in late 
June or early July, only subyearling Chinook salmon 
were still being caught (Fig. 4). The magnitude of peak 
abundances also exhibited species-specific variation, 
with the lowest peak abundances observed for chum 
and sockeye salmon (CPUE<2/1000 m 2 ), moderate 
levels seen for yearling Chinook and coho salmon 
