Fishery bulletin of the Fish and Wildlife Service - NOAA

SALMON RUNS OF THE COLUMBIA EIVER IN 1938 125
with the original assumption. Whether, without the closed period, the peak in the
Bonneville count would have come in the week ending September 10 is perhaps somewhat
doubtful, and no method has occurred to us whereby that can be independently
determined. From the total run (table 12) this would seem to be a reasonable inference,
but it has been based on the assumption that 2 weeks are required for the journey
from the mouth of the river to Bonneville.
In passing, it should be emphasized for future use in similar situations that the
effect of the closed period has been to so increase the Bonneville count immediately
following the beginning of the closed period that it has the effect of shifting the peak
of the count upward. This would be true even if the final week of the open period
had consisted of 6 days instead of 4 days of fishing. In general, the incidence of a
closed period will increase the escapement in the following weeks, but hi this case
the peak of the run happens to coincide so closely with the beginning of the closed
period (probably actually preceding it on the lower river) that the effect is to shift
the peak of the escapement upward. Also, in this particular case, the fact that the
last week of the open season contained only 4 fishing days had the effect of apparently
shifting the peak of the catch downward. The combined result was an apparent
lag of 3 instead of 2 weeks between the peak of the catch in Zones 1 and 2 and the
peak of the count at Bonneville. Similarly, at the beginning of an open period there
will be the reverse tendency for the peak of the escapement to be shifted downward
and the peak of the catch to be shifted upward. Doubtless the peak of the Bonneville
count that occurs during the week corresponding to that of April 30 has been
so modified. Actually this count was made during the week ending May 14, and the
fish passing Bonneville during that week were doubtless partly through Zones 1 and
2 before the fishing season opened on May 1. These rather confusing effects are, of
course, due to the complementary relationship existing between the catch and the
count at Bonneville.
Related to these phenomena is the fact that there appears to have been some
delay hi the passage of fish through Zone 6 following the peak of the run and the
closed season. This is shown particularly by the fact that during the weeks ending
September 10 to October 15 (almost the entire effective fall season) the catch above
Bonneville exceeded the Bonneville count. However, we believe that this does not
indicate a general lower average rate of travel, but is due, rather, to the combined
influence of individual variation in the rate of travel and a constant reduction in the
number of fish passing Bonneville. The anomaly, then, of the existence over a number
of weeks of a greater catch above Bonneville than count over the dam is closely
related to the fact that the peak of the escapement curve is shifted to an earlier date
by the incidence of an open season.
THE JUNE-JULY RUN
As previously mentioned, the June-July run of chinooks is poor compared with
that in May or August, and it is rather generally thought that the populations forming
this part of the run are the most seriously depleted of any. Some evidence of
this was developed at the tune the original study was made, but was not included
in the original report. It has seemed worth while to pursue the investigation further.
As bearing on the extent to which the June-July run has been depleted, we have
examined data secured through the cooperation of the Columbia River Packers Association.
These data are in the form of reports of daily deliveries to this company
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