166 
Fishery Bulletin 106(2) 
Table 2 (continued) 
Species 
Common name 
Occurrence 
(n =78) 
Density 
(no. /1000 m 3 ) 
Number 
captured 
Stage 
collected 
Pleuronectidae (cont.) 
Lyopsetta exilis 
Slender sole 
4 
0.00082 
9 
Eggs 
2 
0.00016 
2 
Larvae 
Microstomus pacificus 
Dover sole 
8 
0.00566 
65 
Eggs 
4 
0.00123 
24 
Larvae 
Parophrys vetulus 
English sole 
6 
0.00101 
11 
Larvae 
Platichthys stellatus 
Starry flounder 
1 
0.00016 
2 
Larvae 
Pleuronichthys decurrens 
Curlfin sole 
4 
0.00504 
5 
Eggs 
1 
0.00015 
2 
Larvae 
Psetticthys melanostictus 
Sand sole 
7 
0.00920 
112 
Eggs 
17 
0.01202 
164 
Larvae 
1 Either Artedius corallinus or A. 
notospilotus. 
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
Figure 3 
Densities of northern anchovy ( Engraulis mordax) eggs sampled off the mouth of the Columbia River, Oregon, in relation 
to sampling date for 1999 through 2004 (note log scale ony-axis). An X represents dates when sampling occurred but no 
northern anchovy eggs were collected. 
from 0 to 1.7 and evenness from 0 to 1. Over all years, 
diversity was highest in April for eggs at both stations 
and for larvae at buoy 1, whereas at buoy 2, peak di- 
versity for larvae occurred in March. Lowest diversities 
occurred in late fall and especially in December. Even- 
ness was highest in April and lowest in December. 
More than half of all species included in the egg- 
stage cluster analysis were flatfish from the families 
Pleuronectidae and Paralichthyidae (Fig. 4) . The most 
closely grouped species were the northern anchovy and 
sanddab. Other taxa with a similar abundance pattern 
included the blacksmelt (Bathylagidae) and Pleuro- 
nectidae. Three sampling groups emerged in the egg 
cluster analysis (Fig. 4). The first group or cluster (A) 
consisted mainly of samples collected in winter-spring 
(December-early May), before the spring transition, and 
was dominated by rex sole and other flatfishes. Cluster 
B was composed of mainly late spring (April-June) 
samples and was dominated by jack mackerel and 
sanddab eggs. In contrast, Cluster C was predomi- 
