There were few significant differences from the controls in 
observed condition scores (see Table 5), however there is a pat¬ 
tern that lower salinity stations accounted for most of these 
differences. In all cases but two, where significant differences 
occurred, the average condition scores were higher than that of 
the controls. These aberrant stations are Stations 9 and 10 
which are the two most upriver stations. 
Condition scores are affected by the seasonal condition 
changes that normally occur in oysters and only partially reflect 
(except in extremes) the oyster's health. Condition scores are 
based on the amount of solid color and how well the oyster fills 
its shell. The buildup of gonad in the spring and the accumu¬ 
lation of glycogen in the fall tend to elevate the score. Con¬ 
versely, low scores should be expected at the end of summer when 
oysters are completely spawned out and have suffered through 
unfavorable high summer temperatures that adversely affected 
their pumping and feeding. Also, oysters that have come through 
a hard long winter and spring with low temperatures and low 
available food have used up a great deal of their reserves (gly¬ 
cogen) and therefore will score low. Still the health of these 
oysters would not be as different as the two separate scores 
seem to indicate. Salinity can also influence oyster condition. 
Oysters in low salinity upriver areas that often warm up early 
will start their gonad development earlier than oysters in the 
more saline downriver or bay areas that warm up slower. Freshets 
often cause upriver salinities that are too low for spawning at 
spawning temperature. These oysters will not spawn and in the 
fall convert their gonad material immediately into glycogen with¬ 
out going through a "summer slump." These oysters may score high 
all year round. However, during the same period the oysters 
downriver are likely to spawn because the salinity is favorable 
at spawning temperatures and enter the fall in low condition. 
After temperatures drop (usually later than upstream), they will 
feed effectively again and increase their score until the water 
temperature is 5°C when they cease feeding and rely on their re¬ 
serve food which decreases their score. Thus, oyster scores 
should be evaluated with season and location in mind using as 
many individuals as possible. It is a subjective comparative 
judgment and should be performed as much as possible by one 
person to eliminate differences between workers. 
Associated organisms and time of occurrence are given in 
Table 6. When trays were inspected on 12 July, there were no 
live commensal organisms present at Station 9, and at Station 
10 the shells were almost clean except for a few live barnacles, 
bryozoan colonies and amphipods. During inspection of oysters 
on 5 August, it was noted that very few commensal organisms were 
present at Stations 6, 7, 8, 9 and 10 and that the shells were 
cleaner than before. On 23 August, it was noted that algae and 
barnacles were dying and decomposing at Stations 6 and 7, and 
26 
