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 Cramer Fish
Sciences
May 21-June 10, 2007, Summary Postcard No. 8
Caswell:
A total of 324 juvenile Chinook salmon were
captured at Caswell Memorial State Park from May 21st through
June 10th. Increasing the season total to 2,828
Chinook. Daily catch ranged from 3 to 33 Chinook (Figure 1).
Individual fork lengths ranged from 63 mm to 106 mm. Mean length
for captured Chinook during this sampling period was 84 mm and mean weight
was 6.7 grams.
Figure
1. Total daily catch contributions of the north, south, and lower rotary
screw traps at Caswell Memorial State Park (RM 8). To date the lower trap has contributed
29% of the total catch.
The contribution of the
season total catch from each trap was 968 for the north trap, 1046 for
the south trap, and 814 for the lower trap. The lower trap captured
93 of the 324 juvenile Chinook salmon, yielding 29% of the total catch
for the sampling period and 29% of the total catch for the season.
Four O. mykiss were captured in the rotary
screw traps during this sampling period (Figure2, Table 1). This
brings the season total of O. mykiss to 22 fish.
Figure 2. O. mykiss smolt (top) and fry
(bottom) captured on May 22nd and June 4th respectively. [click on the photo for enlarged view]
Table 1. Species,
trap location, date, fork length, total length, weight, and smolt index
of captured O. mykiss at Caswell.
No trap efficiency tests were
conducted during the sampling period. Furthermore, due to low catch
numbers and reoccurring poor fish condition no tagging operations were
conducted during this sampling period. Field technicians rated gill color (1 - pale to 5 -
bright red) of all
Chinook in Caswell RST catch, an important diagnostic of columnaris and other infection (Figure 3).
Figure 3. Photo of a juvenile Chinook gill
coloration being inspected on June 5th. [click on the photo for enlarged view]
A summary of gill ratings can
be found in Figure 4. Field technicians observed a decline in fish
condition beginning June 1st and found three mortalities in the
traps on June 6th. Fish condition apparently improved thereafter and no
additional mortalities were observed from June 8th to June 10th.
Figure 4. Chart showing average daily gill
rating (1 - pale to 5 - bright red).
During this sampling period
fifteen different types of incidental species were captured, including
bluegill sunfish, white crappie, unidentified sunfish, gold fish,
Sacramento pikeminnow, Sacramento sucker, tuleperch, western mosquitofish,
prickley sculpin,
white catfish, striped bass, smallmouth bass, largemouth bass, spotted
bass and unidenified bass.
Coded Wire Tagging (CWT):
Coded wire tagging of
juvenile Chinook did not occur during this sampling period. To view the
latest details of the coded wire tagging operations go to the
Coded
Wire Tagging Update #6.
Environmental Data:
Supplemental Vernalis
Adaptive Management Program VAMP flows were scheduled to decrease on
May 21st, however a series of delays to the scheduled flow
reductions have occured to benefit the delta smelt (Hypomesus transpacificus),
a federal and state listed threatened species.
Instantaneous water
temperature taken at Caswell ranged from 58.2°F to 63.1°F.
Turbidity at Caswell ranged from 1.5 NTU to 5.8 NTU. During the
sampling period, releases from Goodwin Dam (GDW) ranged from 747 cfs to
1,504 cfs. Flows at Orange Blossom Bridge (OBB; RM 46.9)
ranged from 756 cfs to 1,291 cfs and at Ripon (RIP; RM 15.8) from 936 cfs
to 1,488 cfs (Figure 5).
Figure 5. Combined traps daily catch at Caswell
State Park and river flow (cfs) at Ripon (RIP; CDEC Station)
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