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February 14-March 6, 2005, Report No.
4
Oakdale:
A total of 61,680 juvenile
Chinook were captured between February 14 and March 6
increasing the season total to 181,997. Daily catch ranged
from 128 to 14,106 Chinook (Figure 1). Average forklength
was 36.3 mm and ranged from 29 mm to 66 mm. Average weight
for captured Chinook was 0.4 g and ranged from
0.2 g to 3.0 g.
Two yearling Chinook (165 mm and 170 mm) were also captured
on March 5, but were not included in the total catch or in
calculations for mean length or weight.
Daily catch peaked on several
occasions during the sampling period following rain events.
The most significant peaks occurred on February 17 (14,106
Chinook) and March 1 (13,253 Chinook). Increased catch
following individual rain events generally lasted 1 to 4
days.
Figure 1. Chinook
Catch at Oakdale versus flow at Orange Blossom Bridge.
Ten
O. mykiss were
captured during the sampling period increasing the season
total to 17 at Oakdale. Eight out of the ten
O. mykiss were
captured on a single date (March 1). Refer to Table 1 below
for data collected from each
O. mykiss
captured. Six of the fish (all SI 5) were retained and were provided
to CDFG for analysis as part of a
Distribution and
Relationship of Resident and Anadromous Central Valley
Rainbow Trout project currently being conducted
by George Edwards at CDFG. Up to 30
O. mykiss
captured in the rotary screw traps during the 2005 season
will be provided to CDFG for their studies.
Table 1.
Date, forklength, smolt index (SI) and weight of
O. mykiss
captured at Oakdale between February 14 and March 6, 2005.
|
Date |
Forklength (mm) |
Smolt Index1 |
Weight (g) |
|
02/17/05
|
240
|
5
|
159.9
|
|
03/01/05
|
274
|
5
|
nd
|
|
03/01/05
|
239
|
5
|
131.2
|
|
03/01/05 |
247
|
5
|
139.2
|
|
03/01/05 |
300
|
5
|
293.4
|
|
03/01/05
|
28
|
2
|
0.2
|
|
03/01/05 |
98
|
3
|
9.5
|
|
03/01/05
|
111
|
3
|
13.7
|
|
03/01/05
|
120
|
4
|
112
|
|
03/05/05
|
263
|
5
|
190.2
|
1Smolt index rating scale:
1-Sac-fry; 2-Fry; 3-Parr; 4-Silvery Parr; 5-Smolt; 6-Adult
Trap efficiency
releases were conducted on five nights between February 15
and March 3 and results of releases are presented in Table
2. Estimated trap efficiencies are consistent with past
year's data under similar flow conditions,
with the exception of the release on February 15. The
estimated trap efficiency on February 15 was lower than
expected based on flow, turbidity and size of fish.
Table 2. Release
and recapture data for trap efficiencies conducted at
Oakdale.
|
Date |
# Released |
# Recaptured |
Trap Efficiency |
Mean Length @ Release (mm) |
Mean Length @ Recapture (mm) |
Turbidity (NTU) |
Flow @ OBB |
|
2/15/05 |
157 |
12 |
7.6% |
34.2 |
35.6 |
3.3 |
261 |
|
2/18/15 |
493 |
30 |
6.1% |
35.5 |
35.6 |
7.4 |
306 |
|
2/23/05 |
451 |
102 |
22.6% |
36.0 |
36.2 |
3.2 |
259 |
|
2/24/05 |
473 |
157 |
33.2% |
35.3 |
36.0 |
3.1 |
251 |
|
3/3/05 |
479 |
168 |
35.1% |
35.0 |
36.7 |
3.0 |
258 |
Caswell:
A total of 5,490 juvenile
Chinook were captured between February 14 and March 6
increasing the season total to 19,771. Daily catch ranged
from 12 to 523 Chinook (Figure 2).
Average forklength was 49.7 mm and ranged from 29 mm to 71
mm. Average weight for captured Chinook was 1.3 g and
ranged from 0.3 g to 3.4 g.
Average forklength increased by almost 13 mm and average
weight increased by almost 1 g since the previous sampling
period.
Figure 2. Chinook
Catch at Caswell versus flow at Ripon.
Seven
O. mykiss were
captured during the sampling period. Refer to Table 3 below
for data collected from each
O. mykiss
captured. These fish were also retained and provided to
CDFG for analysis as part of a
Distribution and
Relationship of Resident and Anadromous Central Valley
Rainbow Trout project..
Table 3. Date, forklength, smolt index and weight of
O. mykiss captured at Caswell between February 14 and
March 6, 2005.
| Date |
Forklength
(mm) |
Smolt
Index2 |
Weight (g) |
|
02/17/05
|
261
|
5
|
167
|
|
02/17/05
|
271
|
5
|
190.4
|
|
02/17/05
|
270
|
5
|
193.9
|
|
02/19/05
|
264
|
5
|
170.9
|
|
02/24/05
|
263
|
5
|
173.5
|
|
03/01/05
|
254
|
5
|
163.2
|
|
03/02/05
|
229
|
5
|
116.5
|
2Smolt index
rating scale: 1-Sac-fry; 2-Fry; 3-Parr; 4-Silvery Parr;
5-Smolt; 6-Adult
Trap efficiency releases were
conducted on five nights between February 19 and March 1 and
results of releases are presented in Table 4. Estimated
trap efficiencies are consistent with past year's data based
on flow, turbidity and fish size.
Table 4. Release
and recapture data for trap efficiency conducted at
Caswell.
|
Date |
# Released |
# Recaptured |
Trap Efficiency |
Mean Length @ Release (mm) |
Mean Length @ Recapture (mm) |
Turbidity (NTU) |
Flow @ RIP |
|
02/19/05 |
391 |
47 |
12.0% |
39.8 |
38.6 |
21.6 |
448 |
|
02/20/05 |
475 |
59 |
12.4% |
39.3 |
41.8 |
10.1 |
403 |
|
02/21/05 |
140 |
32 |
22.7% |
44.5 |
44.6 |
10.9 |
451 |
|
02/28/05 |
117 |
12 |
10.3% |
54.2 |
52.8 |
3.9 |
318 |
|
03/01/05 |
198 |
28 |
14.1% |
55.1 |
53.1 |
7.5 |
439 |
Environmental Data:
Several rain events caused
environmental conditions to fluctuate during the sampling
period. Instantaneous temperature fluctuated between 50°F
and 53°F
at Oakdale and between 53°F
and 58°F
at Caswell. Turbidity ranged from 2.6 NTU to 22.4 NTU at
Oakdale and from 3.7 NTU to 27.0 NTU at Caswell. During the
sampling period, flow releases from Goodwin Dam (GDW)
fluctuated between 225 cfs and 230 cfs. Flows at Orange
Blossom Bridge (OBB; RM 46.9) ranged from 242 cfs to 374 cfs
and at Ripon (RIP; RM 15.8) from 272 cfs to 624 cfs.
The difference between the flow released at GDW and the
recorded values at OBB and RIP was a result of run-off
produced by rain events.
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