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November
28 through December 11, 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 280 Chinook (daily
range: 2 to 62) passed upstream of the weir between November 28
and December 11 increasing the season total to 3,593
Chinook. Whereas, a total of 4,634 and 4,377 Chinook passed the
weir by the same date in 2003 and 2004, respectively.
In previous years, Chinook
abundance either drastically declined during the month of
December (i.e., only 63 Chinook in 2004) or remained steady
throughout December but declined drastically in January (i.e.,
488 Chinook in December 2003 and
19 in January
2004). Chinook abundance in 2005 appears to be following the
trend observed in 2003 since 197 Chinook have been observed
already during the first half of December.
No
O. mykiss were
observed passing the weir or in the daily snorkel surveys during
the sampling period. Other species observed included Sacramento
sucker
and Sacramento pikeminnow.
Figure 1.
(Top) photo series of a 790 mm (TL) male Chinook with fungus going through the Vaki on
November 30, 2005; (bottom) photo series of a 830 mm (TL) male Chinook
with fungus passing through the Vaki on December 7, 2005.
Environmental conditions
fluctuated at the weir site during the sampling period.
Releases from Goodwin Dam fluctuated between 353 cfs and 380 cfs.
Daily instantaneous measurements of turbidity, DO, and water
temperature ranged between 0.3 and 1.5 NTU; 9.5 mg/L and
11.3 mg/L; and 47.1ºF and 52.7ºF, respectively. DO at Rough 'n
Ready Island (RRI) in the San Joaquin River's Deep Water Ship
Channel ranged from 5.1 mg/L to 6.5 mg/L and water temperature
ranged from 51.8ºF to 55.6ºF.
Figure 2.
Weather conditions at the Stanislaus weir get foggy and cold as
winter approaches.
Trapping:
Three trapping events were
conducted at the Stanislaus weir during the sampling period and
a total of 41 Chinook were captured increasing the season total
to 307. The length of Chinook captured to date ranged from 470
mm to 1,080 mm (avg=785 mm). Fifty-seven percent of the Chinook
were female (176 Chinook), forty-two percent were male (129
Chinook), and less than one percent were unknown gender (2
Chinook). Twelve percent (37 Chinook) were grilse (<600 mm) and
five percent (14 Chinook) were ad-clipped.
Figure 3.
Photos taken of Chinook during trapping periods (left to right):
765 mm (TL) female Chinook; an 830 mm (TL) female Chinook with
large gash behind dorsal fin; 835 mm (TL) male Chinook. |
