|
January 12 through
February 18, 2007, Report No.
1
Waterford:
An 8-foot
rotary screw trap was installed on January 11-12 near the
town of Waterford (RM 30). The trap sampled a total of
23 out of 37 days between January 12 and February 18. A total of
751 juvenile Chinook salmon were captured during the
sampling period. Daily catch ranged from 0 to 246 Chinook (Figure
2). Average forklength was 44.8 mm and ranged from 30 mm to
130 mm. Average weight was 3.6 g and ranged from 0.2 g to
24.6 g.
One yearling Chinook salmon (166 mm; 50.6
g) was captured at the Waterford site during this
sample period, but was not included in the total catch or
in calculations for mean length or weight.
One O. mykiss (290 mm TL; 209 g) was captured in the rotary screw trap
during this sampling period. The caudal fin was eroded
and appeared to have a fungal infection.
Figure 1. Rotary
screw trap near Waterford on the Tuolumne River.
Figure 2. Chinook
salmon catch at Waterford versus flow at La Grange (LGN);
arrows indicate periods the trap was not sampled.
Two
trap efficiency tests were conducted at Waterford using natural Chinook
captured from the trap. The first release was conducted on
February 13
and consisted of 35 marked fish. A total of one marked fish was
subsequently recaptured (i.e., trap efficiency = 2.9%); mean length of
Chinook at release was 35.1 mm; and mean length of Chinook at recapture
was 37.0 mm. The second release was conducted on February 14 and
consisted of 238 marked fish. A total of 22 marked fish were
subsequently recaptured (i.e., trap efficiency = 9.2%); mean length of
Chinook at release was 34.9 mm; and mean length of Chinook at recapture
was 34.7 mm. Releases at LaGrange Dam (LGN) on February 13 and February 14
were 339 cfs and 338 cfs, respectively.
Environmental Data:
Instantaneous water temperature taken at the Waterford trap
ranged between 45°F and 54°F; turbidity ranged from
0.05 NTU to 6.79 NTU; and flows at La Grange ranged between
338 cfs and 339 cfs.
|
