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October
17 through October 30, 2005
Note: Data is preliminary and subject to revision. Data
presented in this report are only from the Vaki RiverWatcher and
numbers may increase after the data on the back up system is
analyzed and compared. Weir Update:
A total of 1,137 Chinook (daily
range: 7 to 280) passed upstream of the weir between October 17
and October 30 increasing the season total to 1,651
Chinook. Whereas, a total of 2,370 and 2,075 Chinook passed the
weir by the same date in 2003 and 2004, respectively. A total of
978 Chinook passed the weir during the 2005 Fall attraction flow
period (i.e., October 18 through October 28). The peak in
Chinook passage (i.e., 280 fish) was observed on October 20 and
was correlated to the initial increase in flow (2 day lag time
to reach the San Joaquin River). Other species observed
included Sacramento sucker, Sacramento pikeminnow, catfish,
striped bass, carp, and black bass.
Figure 1. Ripe adult male Chinook and
chrome grilse Chinook passing through the Vaki on October 28,
2005.
Environmental conditions
fluctuated at the weir site during the sampling period. Daily
instantaneous measurements of turbidity, DO, and water
temperature ranged between 1.2 and 3.7 NTU; 9.6 mg/L and 10.7
mg/L; and 54.6ºF and 57.2ºF, respectively. DO at Rough 'n Ready
Island (RRI) in the San Joaquin River's Deep Water Ship Channel
ranged from 6.6 mg/L to 7.6 mg/L and water temperature ranged
from 61.6ºF to 65.6ºF.
Releases from Goodwin Dam
fluctuated between 351 cfs and 1,010 cfs between October 17 and
October 30. Fall attraction flows on the Stanislaus River
occurred between October 18 and October 28. Releases from
Goodwin Dam were increased to approximately 1,000 cfs over a
two-day period (October 18-19) and remained elevated for a
six-day period (October 20-25). Releases were then decreased to
approximately 350 cfs over a three day period (October 26-28)
where it will remain until December 31, 2005.
During the Fall attraction flow
period, a considerable amount of labor was expended to ensure
the weir remained clean of debris and functioned properly (Figure
2). Our crew was on-site 24 hours per day for the first
3 days and then cleaned the weir a minimum of 3 times per
24-hour period for the remainder of time while flows were at
1,000 cfs. Plastic barrels were installed underneath the weir
panels where velocity was the greatest to help keep the panels
afloat. We did not experience any major problems during the
attraction flow and successfully kept the weir panels at the
surface for the duration of the Fall attraction flow period.
Figure 2.
Stanislaus
River weir under high flow conditions (1,000 cfs) during the
2005 Fall attraction flows.
Trapping:
One trapping event was conducted
before flows reached 1,000 cfs at the weir site and another
event was conducted as flows began to decrease back to 350 cfs.
Although we normally trap at the weir if turbidity increases to
above 3.0 NTU, high water levels during the attraction flow
period precluded us from trapping. Turbidity ranged from 3.6 to
3.7 NTU during a three day period following the initial increase
in flow. Although the turbidity during a short period of the
attraction flow was not optimal, we were still able to obtain
photos that were clear enough to identify between a Chinook
salmon or O. mykiss.
Figure 3.
Technician
collecting scales from Chinook (left); measuring male Chinook
(middle); adipose fin clipped Chinook (right).
During the two trapping events, a
total of 55 Chinook were captured increasing the season's
cumulative total to 99. The length of Chinook captured to date
ranged from 525 mm to 1,020 mm (avg=785 mm). Fifty-seven
percent of the Chinook were female (56), forty-one percent were
male (41) and two percent were unknown (2). Seven percent (7
Chinook) were grilse (<600 mm) and four percent (4 Chinook) were
ad-clipped. |
