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March 7 through 20, 2005, Report No.
5
Oakdale:
A total of 2,575 juvenile
Chinook were captured between March 7 and March 20
increasing the season total to 184,572. Daily catch
fluctuated throughout the sampling period and ranged
from 26 to 642 Chinook (Figure 1). Average forklength
was 42.3 mm and ranged from 28 mm to 98 mm. Average weight
for captured Chinook was 0.9 g and ranged from
0.2 g to 6.5 g.
Average forklength increased by 6 mm and average weight
increased by 0.5 g since the previous sampling period.
Similar to past years, daily catch decreased significantly
as average length increased over 40 mm.
Figure 1. Chinook
Catch at Oakdale versus flow at Orange Blossom Bridge.
One
O. mykiss (202
mm; SI 5) was
captured on March 8 increasing the season
total to 18 at Oakdale. The fish was retained and will
be 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.
Trap efficiency
releases were conducted on four nights between March 10 and
March 17 and results of releases are presented in Table
1.
Estimated trap efficiencies
are consistent with past year's data based on fish size and
flow. Past year's data suggests that as Chinook reach
the parr lifestage their catch efficiency decreases
significantly.
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 |
|
03/10/05 |
258 |
43 |
16.7% |
37.8 |
37.1 |
2.7 |
240 |
|
03/11/05 |
156 |
32 |
20.5% |
40.7 |
37.8 |
2.7 |
240 |
|
03/16/05 |
181 |
14 |
7.7% |
38.8 |
36.1 |
1.9 |
237 |
|
03/17/05 |
111 |
11 |
9.9% |
39.3 |
44.7 |
2.2 |
237 |
Caswell:
A total of 942 juvenile
Chinook were captured between March 7 and March 20
increasing the season total to 20,713. Daily catch ranged
from 15 to 245 Chinook (Figure 2).
Average forklength was 57.0 mm and ranged from 30 mm to 86
mm. Average weight for captured Chinook was 2.2 g and
ranged from 0.3 g to 4.2 g.
Average forklength increased by more than 7 mm and average
weight increased by almost 1 g since the previous sampling
period.
A
yearling Chinook (162 mm) was
also captured on March 8, but was not included in the total
catch or in calculations for mean length or weight. No
O. mykiss were
captured during the sampling period.
Figure 2. Chinook
Catch at Caswell versus flow at Ripon.
Trap efficiency releases were
conducted on March 8-9 and
results of releases are presented in Table 2. Estimated
trap efficiencies are consistent with past year's data based
on flow, turbidity and fish size.
Table 2. 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 |
|
03/08/05 |
227 |
6 |
2.6% |
53.3 |
56.7 |
5.0 |
300 |
|
03/09/05 |
202 |
21 |
10.4% |
55.5 |
56.6 |
5.0 |
289 |
Environmental Data:
Environmental conditions
remained fairly stable during the sampling
period. Instantaneous temperature fluctuated between 52°F
and 58°F
at Oakdale and between 56°F
and 62°F
at Caswell. The increase in water temperature was
correlated to an increase in ambient air temperature.
Turbidity ranged from 1.3 NTU to 5.9 NTU at Oakdale and from
2.4 NTU to 7.2 NTU at Caswell. During the
sampling period, flow releases from Goodwin Dam (GDW)
fluctuated between 226 cfs and 229 cfs. Flows at Orange
Blossom Bridge (OBB; RM 46.9) ranged from 235 cfs to 249 cfs
and at Ripon (RIP; RM 15.8) from 270 cfs to 321 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 a March 6 rain event.
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