 Cramer
Fish Sciences
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Summary Postcard No. 5
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March 26 - April 15, 2007
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A sequentially tagged Chinook was caught by
the California Department of Fish & Game (CDFG) during
their Kodiak trawl survey on the lower San Joaquin River at
Mossdale. This marks the
first recapture of a tagged fish in the Mossdale
trawl. The fish was
released on March 22, 2007 at Caswell Memorial State Park
and was recaptured on April 4, 2007 at Mossdale. At the time of
tagging the Chinook had a forklength of 65 mm and weighed
3.0 g (Figure 1). At recapture the fish had a forklength of
71 mm.
Figure 1. Photo of the 65mm Chinook salmon parr tagged on March 21, 2007. [click on the photo for
enlarged view]
Catches of juvenile
Chinook have continued to be low at Caswell Memorial State
Park (see
Rotary Screw Trapping Summary #5 for more
details). A total of 21 Chinook were tagged during this
sampling period. There were no immediate mortalities due to
tagging. The fish were held overnight to evaluate 24-hour
mortality and tag retention. Of the 21 fish held; four
mortalities were observed before release, five fish did not retain
their tags and one fish escaped from the net pen. A total of
11 tagged fish were released below the lower Caswell rotary
screw trap.
Chinook catch numbers are
expected to increase when Stanislaus River flows from
Goodwin Dam (GDW) increase to 1,500 cfs for VAMP beginning
on April 19th. Our staff has refined the coded wire tagging
protocol over the past several weeks, and is continually
working to insure all equipment and supplies are ready for
any number of fish at a moments notice. (Figure 2 and Figure
3).
Figure 2. Senior fisheries biologist Ayesha Gray
examining a coded wire tag. [click on the photo for
enlarged view]
Figure 3. A cut full length coded wire tag as seen through the tag viewer. [click on the photo for
enlarged view]
Environmental
Data:
Instantaneous water
temperature taken at the Caswell rotary screw trap ranged
from 54.0°F to 60.0°F. Turbidity at Caswell ranged
from 1.6 NTU to 4.0 NTU. During the sampling period
releases from Goodwin Dam (GDW) ranged from 500 cfs to 510 cfs.
Flows at Orange Blossom Bridge (OBB; RM 46.9) ranged from
421 cfs to 434 cfs and at Ripon (RIP; RM 15.8) from 523 cfs
to 582 cfs.
We
have sent five specimens to Scott Foott at the regional
U. S. Fish and Wildlife Service Fish Health Laboratory
for analysis. Further details will be available in
upcoming updates.
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.
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