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February
12-March 4, 2007, Summary
Postcard No.
3
Caswell:
A total of 494
juvenile Chinook salmon were captured in the North and
South traps from February 12th
to March 4th. Daily catch ranged from 0
to 280 Chinook. Individual forklengths ranged from 29 mm to 54 mm. Mean length for captured Chinook
during this sampling period was 35 mm
and mean weight was 0.4 grams. Two Chinook salmon
yearlings (FL 147 mm, 47.4 g; FL 145 mm, 36.2 g) were captured on
February 24th and February 26th,
respectively (Figure 1).
Figure 1. A yearling Chinook salmon captured on
Feb. 24th (FL: 147 mm, W: 47.4 g). [click on the photo for
enlarged view]
Four O. mykiss
were captured in the South rotary screw trap during this
sampling period and zero in the North trap (Table 1, Figure 2).
|
Trap
|
Date
|
Time
|
Fork
length(mm)
|
Total
length(mm)
|
Weight
(g)
|
Smolt
Index
|
|
South
|
2/28/07
|
11:45
|
249
|
270
|
140.2
|
5
|
|
South
|
2/27/07
|
21:15
|
220
|
232
|
np
|
5
|
|
South
|
2/27/07
|
10:30
|
223
|
239
|
102.1
|
5
|
|
South
|
2/27/07
|
10:30
|
220
|
239
|
102.3
|
5
|
|
Lower
|
2/26/07
|
09:30
|
285
|
317
|
205
|
5
|
Table 1. Trap location,
date, time, forklength, total length, weight, and smolt
index of captured O. mykiss at Caswell State Park (RM
8).
Figure 2. Photo of an O.mykiss
captured on Feb. 28th (FL: 249 mm, W:
140.2 g). [click on the photo for
enlarged view]
In the
Lower
Caswell trap a total of 158 juvenile Chinook
salmon were captured from February 12th
to March 4th. Daily catch ranged
from 0 to 104 Chinook. Individual forklengths
ranged from 31 mm to 48 mm. Mean length for
collected Chinook during this sampling period was 38 mm
and mean weight was 0.4 grams. Zero yearling
Chinook salmon were captured in the lower trap during
this sampling period. The lower trap yielded 23% of
the season total catch of all three traps combined (Figure
3).
Figure 3. Season total catch for the North, South and
Lower traps as well as the percent of total catch for the lower trap.
One O. mykiss
was captured in the lower rotary screw trap during this
sampling period (Table 1).
Two
trap efficiency tests were conducted during this
sampling period; 261 upper caudal and 82 lower
caudal fin-clipped wild juvenile Chinook salmon were
released on March 2nd and 3rd,
respectively. Eight fin-clipped Chinook were
recaptured in the North and South traps on March 2nd
and zero on March 3rd. These tests
yielded 3.1% (Mar. 2nd) and 0% (Mar. 3rd)
trap efficiency results. The Lower trap recaptures
and the combined efficiency of all three traps were
added to the table below for reference (Table 2).
|
Date |
Mark |
#Released North/South Traps |
#Recaptured North/South Traps |
North/South Trap Efficiency |
#Recaptured Lower Trap |
Combined Traps Efficiency |
|
March 2nd |
Upper Caudal Fin-clip |
261 |
8 |
3.1% |
1 |
3.5% |
|
March 3rd |
Upper Caudal Fin-clip |
82 |
0 |
0.0% |
1 |
1.2% |
|
|
Total |
343 |
8 |
2.3% |
2 |
2.9% |
Table 2. Trap efficiency
data for the North/South traps, Lower trap, and all the
traps combined at Caswell State Park (RM
8).
During the sampling period thirteen incidental species were captured, including white catfish, bluegill sunfish, tule
perch, prickly sculpin,
hardhead, Sacramento sucker, western mosquitofish,
largemouth bass, hitch, golden shiner, Sacramento blackfish,
Sacramento sucker and unidentified lamprey (Figure 4).
Figure 4. Photo of a tule perch captured on Feb. 24th
(FL: 83 mm).
[click on the photo for
enlarged view]
Coded Wire Tagging (CWT):
On Monday, February
26th, Jerry Big
Eagle (Big Eagle & Associates) was on site to assist us
in setting up our MARK
IV coded wire tagging devices and begin our daily
tagging operations (Figure 5). Tag placement
and depth was carefully set and monitored throughout the
tagging operation. A total of 458 juvenile Chinook salmon were
tagged and released
during this sampling period (Figure 6) with a batch code
unique for the week of Feb. 26th to Mar. 4th.
Our tagging retention was 92.0% and our tagging
mortality was 5.3% during this sampling period.
To deter vandalism and theft we
installed wheel locks on the trailer and set up a fence
around a designated work area (Figure 7). Please review the final
Detailed Study Plan for Coded Wire Tagging of Chinook Salmon
in The Stanislaus River
for more information on the
CWT study.
Figure 5. Field technician loading 1/2 length coded wire
tag (CWT) into the MARK IV injector.
[click on the photo for
enlarged view]
Figure 6. Field technician injecting a 1/2 length coded
wire tag (CWT) into the snout of a Chinook salmon fry.
[click on the photo for
enlarged view]
Figure 7. Fencing around trailer and designated work
area.
[click on the photo for
enlarged view]
Environmental
Data:
Instantaneous water
temperature taken at the Caswell rotary screw trap ranged
from 46.0°F to 52.6°F. Turbidity at Caswell ranged
from 1.0 NTU to 10.8 NTU. During the sampling period
releases from Goodwin Dam (GDW) ranged from 806 cfs to 1,505 cfs.
Flows at Orange Blossom Bridge (OBB; RM 46.9) ranged from
614 cfs to 1,229 cfs and at Ripon (RIP; RM 15.8) from 763 cfs
to 1,404 cfs. Click here if you need Adobe Acrobat
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