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Fishery Bulletin 106(2) 
with a peak in June. We are not certain whether the 
timing of northern anchovy spawning has shifted to 
earlier months, whether this early spawning was missed 
by previous surveys, or whether we have two different 
age-groups spawning at different times. Nevertheless, 
our results indicate that timing of northern anchovy egg 
surveys is an important parameter to consider during 
surveys to estimate spawning biomass (Emmett et al., 
1997) and feeding success relative to plankton produc- 
tion cycles (Bollens et al., 1992). 
Jack mackerel, which generally spawn off southern 
California (MacCall and Stauffer, 1983), are not com- 
monly collected as juveniles very far north in the Cali- 
fornia Current. Because jack mackerel eggs hatch in 4.3 
days at 12°C (Farris, 1961) and because we observed 
jack mackerel larvae, it appeared that jack mackerel 
spawned in the general vicinity of our study area. Jack 
mackerel spawning has been reported off Washington 
State and southern Oregon (Ahlstrom, 1956), but not 
for many years. Ahlstrom (1956) noted that there is a 
northward progression of the spawning season in ar- 
eas north of Point Conception, California. During our 
study period, it was possible that adult jack mackerel 
moved north and into cooler waters inshore to feed 
and spawn. The recent capture of age-0 jack mackerel 
during pelagic fish surveys off Oregon and Washington 
(Brodeur et al., 2006) indicates that jack mackerel have 
recently spawned and recruited successfully off the 
Pacific Northwest coast. 
The occurrence of rare taxa, such as opah, can be 
attributed to the long incubation time (up to 3 weeks) 
exhibited by most lampriform fish eggs (Olney, 1984). 
In this time, an egg spawned in the open ocean, the 
normal habitat of this species, could drift inshore to 
our sampling area. Similarly, Pacific viperfish eggs, 
released in the open ocean, can drift inshore. Little is 
known about their egg incubation period. 
The occurrence of several offshore ichthyoplankton 
species in our study area may be related to the lo- 
cal topography. The Astoria Canyon lies directly sea- 
ward from the mouth of the Columbia River. During 
the upwelling season, the canyon causes currents to 
flow landward (Hickey, 1997), thus carrying normally 
offshore organisms closer to shore. Bosley et al. (2004) 
concluded that currents over the Astoria Canyon concen- 
trate oceanic organisms and transport them shoreward 
and these actions may explain the occurrences of opah. 
Pacific viperfish, and jack mackerel eggs, and other 
offshore species (Richardson and Pearcy, 1977) in our 
coastal sampling. 
Egg and larval composition at the two sampling sta- 
tions did not differ significantly, probably because they 
were relatively close and thus had similar environmen- 
tal conditions. Out of a total of five physical variables 
tested, only salinity was found to be significantly differ- 
ent between the two stations. Surface salinity is highly 
variable in this region because of the proximity of the 
Columbia River plume. While the plankton tow depths 
at each station were the same (40 m), we would have 
missed eggs and or larvae occurring below 40 m at the 
station farther offshore (buoy 1), which was in substan- 
tially deeper water. Boehlert et al. (1985) and Auth and 
Brodeur (2006) found fish larvae at depths greater than 
40 m off the coast of Oregon, although the majority of 
fish larvae were in surface waters. 
The cluster dendrograms were dominated by flatfish 
species because of the high number of pleuronectid 
species found along the Oregon coast, as well as the 
tendency of most of these species to have pelagic eggs. 
Overall patterns in the egg and larval clusters changed 
seasonally, and many of the samples collected during 
the downwelling or upwelling seasons were clustered 
together. MRPP analysis verified that season was an 
significant contributor to these cluster groups. The lar- 
val indicator species for downwelling conditions were 
English sole and Dover sole, which are typically win- 
ter spawners (although some spawning may occur all 
year). The indicator species for the upwelling season 
was northern anchovy, which spawns primarily in the 
spring and summer. In general, benthic and nearshore 
species spawn in winter, when larvae are less likely 
to be transported offshore. In 2003, the PDO shifted 
from a cool (negative) to a warm (positive) phase. This 
change resulted in southern or offshore taxa becoming 
more abundant in 2003-04. However, ichthyoplankton 
taxa in 2003 and 2004 were also significantly different 
mainly because of substantial increases in eggs and 
larvae of northern anchovy, a taxon that is not southern 
affiliated. The increase in northern anchovy eggs and 
larvae appeared linked to an increase in the abundance 
of the adult population. 
Large-scale climate variability (as observed dur- 
ing our study period) can cause large changes in fish 
populations (Cushing, 1982; Beamish, 1993; Francis 
et al., 1998; Chavez et al., 2003). Pearcy (2002) and 
Brodeur et al. (2003, 2006) found that abnormal ocean 
conditions alter the ichthyofauna in the California Cur- 
rent region. Changing climate conditions can alter 
currents that advect fish eggs and larvae to or away 
from nursery areas, thus affecting recruitment. Al- 
tered currents may also lower the density and change 
the species composition of planktonic food organisms 
(Peterson and Schwing, 2003) and thus inhibit lar- 
val fish from finding adequate prey resources. In late 
2002, the PDO (Mantua et al., 1997) became positive 
(with warm conditions) after four years of being nega- 
tive (with cold conditions) (Goericke et al., 2005) and 
caused warmer ocean temperatures, increased diversity 
of warm-water copepods, and decreased cold-water co- 
pepods in the California Current (Hooff and Peterson, 
2006). Changes in ocean temperatures can also cause 
shifts in the locations or timing of spawning and affect 
developmental durations through the early life stages 
of fishes (Sabates et al., 2006; Phillips et al., 2007). 
Faster development through the egg and yolk-sac stages 
may help to minimize the time eggs are vulnerable to 
invertebrate predation (Bailey, 1981). In the California 
Current region, upwelling is the dominant feature that 
influences primary production, and therefore any cli- 
mate-induced change that affects upwelling or Califor- 
