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May 9 through May 22, 2005, Report No.
3
Chinook
A total of 414 natural
juvenile Chinook were captured at Grayson (RM 5) between May
9 and May 22 increasing the season total to 1,073.
Daily catch ranged from 2 to 52 Chinook (Figure 1). Average
forklength was 92 mm and ranged from 74 mm to 118 mm. A 33
mm O. mykiss
fry was
captured on May 14.
Figure 1. Chinook
Catch at Grayson versus flow at Modesto.
The California Department of
Fish and Game (CDFG) released approximately 75,000 coded-wire
tagged (CWT) Chinook from Merced River Hatchery (MRH) at La
Grange (RM 52.2) on April 18 to estimate smolt survival
through the lower Tuolumne River. A total of 28 CWT fish were
captured at Grayson (RM 5) between May 9 and May 22 increasing
the season total to 342 CWT fish. Daily catch ranged between
0 and 7 CWT fish (Figure 2). Average forklength was 94 mm and
ranged from 84 mm to 106 mm.
Figure 2. CWT
Catch at Grayson versus flow at Modesto.
Other species
A total of 5 non-salmonid
species were captured in the traps during the sampling period
including Channel catfish, Inland silverside, Sacramento
pikeminnow, Sacramento sucker, and White catfish. Of these,
White catfish (n = 10)
were the most abundant and were 41 mm to 72 mm
in length. Daily catch of other non-salmonids species ranged
between 1 and 2 individuals.
Environmental Data
Environmental conditions
fluctuated throughout the sampling period as a result of
increasing reservoir releases that began around May 18 when
inflow into Don Pedro more than doubled. Instantaneous
temperature at Grayson fluctuated between 53° F and 57° F and
turbidity ranged from 1.7 NTU to 4.5 NTU. During the sampling
period, flow at La Grange Dam (LGN; RM 52.2) ranged between
4,217 cfs and 6,614 cfs. Flows at Modesto (MOD; RM 16.3)
ranged from 4,091 cfs to 5,931 cfs.
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