Table 1. Biosampling data for O. mykiss captured at Shelton Road between January 3 and January 16, 2011. Parentheses indicate range.
 

Figure 2. Stanislaus River rotary screw trap at Oakdale.

The Stanislaus River rotary screw trap at Oakdale (RM 40) initiated sampling on January 3 and continued through the reporting period (Figure 2). A total of 3,132 juvenile Chinook salmon and 3 juvenile O. mykiss were captured. Daily catch of Chinook salmon ranged between 7 and 1,215 individuals. Average forklengths and weights of Chinook salmon and O. mykiss are provided in Table 2 for the 737 Chinook and 3 O. mykiss that were measured. Most of the measured Chinook were fry (n=728) but a few smolts were also recorded (n=9). The O. mykiss that were capture were rated as silvery parr (n=1) and smolt (n=2).

Figure 3. Marking fish for an efficiency experiment conducted for the Stanislaus River rotary screw trap at Oakdale.

Instantaneous temperature recorded at the trap ranged from 44.4�F to 49.8�F, and turbidity ranged from 0.45 NTU to 19.74 NTU. Daily average flow at Goodwin Dam (GDW) ranged between 201 cfs and 217 cfs, and flows at Ripon (RIP) decreased from 1,336 cfs and 266 cfs (Figure 4).

Three trap efficiency experiments were conducted with naturally spawned juvenile Chinook salmon marked caudal fin green (CFG; Figure 3). Preliminary capture efficiency estimates from these releases were 23.7%, 26.3% and 34.4% at flows of 204 cfs, 205 cfs and 206 cfs, respectively (Table 3).

Table 3. Trap efficiency tests conducted at Oakdale between January 3 and January 16, 2011.

Figure 4. Daily Chinook salmon catch at Oakdale and Stanislaus River flow recorded by Goodwin Dam (GDW) and Ripon (RIP), 2010.

The Stanislaus River rotary screw trap at Caswell State Park (RM 8) was installed December 14, 2010 and intermittently sampling  was conducted through the reporting period.  A total of 76 juvenile Chinook salmon have been captured so far this season. Daily catch ranged between 0 and 39 Chinook salmon.

No O. mykiss have been captured so far this season.

No trap efficiency experiments were conducted during the reporting period.

Instantaneous temperature recorded at the trap ranged from 46.0�F and 53.4�F, and turbidity ranged from 2.23 NTU to 53.20 NTU. Daily average flow at Ripon (RIP) declined from a peak of 1,397 cfs to 235 cfs.

Table 5. Biosampling data for Chinook salmon captured and measured at Waterford between January 3 and January 16, 2011. Parentheses indicate range.

No O. mykiss were captured during this reporting period.

Instantaneous temperature taken at the trap ranged from 47.3�F to 50.1�F, and turbidity ranged from 1.82 NTU to 8.04 NTU. Daily average flow at La Grange (LGN) ranged from 2,150 cfs to 5,350 cfs.

One trap efficiency experiment was conducted during the reporting period with naturally spawned juvenile Chinook salmon marked caudal fin orange (CFO). The preliminary estimated capture efficiency was 0.7% at a flow of 2,150 cfs (Table 6).
 

Table 6. Trap efficiency tests conducted at Waterford between January 3 and January 16, 2011.

Figure 5. Daily Chinook salmon catch at Waterford and Tuolumne River flow recorded at La Grange (LGN) and Modesto (MOD) between December 1, 2010, and January 16, 2011.

Figure 6. Tuolumne River rotary screw traps at Grayson.

The Tuolumne River rotary screw traps at Grayson (RM 5) were installed on January 6, 2011 and operated continuously between January 6 and January 16 (Figure 6). A total of 192 Chinook salmon were captured during the reporting period. Average forklengths and weights of all Chinook salmon are provided in Table 7. Most of the fry were buttoned up (n = 186), although a few sac-fry (n = 6) were also observed. 

Table 7. Biosampling data for Chinook salmon captured and measured at Grayson between January 6 and January 16, 2011. Parentheses indicate range.

Instantaneous temperature taken at the trap ranged from 47.8�F to 52.3�F, and turbidity ranged from 2.50 NTU to 6.09 NTU. Daily average flow at Modesto (MOD) fluctuated during the reporting period, declining from a peak at 7,370 cfs to 2,780 cfs (Figure 7).

One trap efficiency experiment was conducted with naturally spawned juvenile Chinook salmon marked caudal fin pink (CFP). The preliminary capture efficiency estimate from the release was 3.5% at a flow of 3,190 cfs (Table 8).

Table 8. Trap efficiency tests conducted at Grayson between January 6 and January 16, 2011.

Figure 7. Daily Chinook salmon catch at Grayson and Tuolumne River flow recorded at La Grange (LGN) and Modesto (MOD) between January 1 and January 16, 2011.

The Mokelumne River rotary screw trap at Vino Farms (RM 54) continued intermittent sampling, and a total of 406 juvenile Chinook salmon were captured through the end of the reporting period.

Average daily flow from Camanche Reservoir (CMN) generally decreased from 2,598 cfs to 1,121 cfs (Figure 8). Instantaneous temperature ranged between 48.7�F and 51.8�F, and instantaneous turbidity ranged between 3.11 NTU and 4.68 NTU.

One juvenile O. mykiss measuring 122 mm was captured on January 8, increasing the season total count to two.

observed this season had adipose fin clip.

Daily average flow in the Stanislaus River at Goodwin Dam (GDW; RM 58) fluctuated between 201 cfs and 217 cfs (Figure 9). Flow at Ripon (RIP; RM 15) decreased from 1,336 cfs to 262 cfs. Note: flows downstream of Goodwin Dam may differ from dam releases due to irrigation, precipitation and other factors.

Instantaneous water temperature measured at the weir ranged between 46.5˚F and 49.8˚F, and daily average water temperature at Ripon (RPN; RM 15) ranged between 46.4˚F and 51.6˚F (Figure 10). Instantaneous turbidity ranged between 0.94 NTU and 26.20 NTU (Figure 11). Instantaneous dissolved oxygen at the weir ranged between 9.55 mg/L and 10.61 mg/L, and daily average dissolved oxygen at Ripon (RPN; RM 15) ranged from 8.53 mg/L to 10.10 mg/L (Figure 12).

Table 9. Net passage counts for all species between January 3 and January 16, 2011 at the Stanislaus River Weir.

Figure 9. Daily upstream adult Chinook passage at the Stanislaus River weir in relation to daily average flow (cfs) recorded in the Stanislaus River at Goodwin (GDW) and Ripon (RIP), and in the San Joaquin River at Vernalis (VNS) in 2010 and 2011.

Fall-run Chinook salmon returning to the Mokelumne River are counted annually by East Bay Municipal Utility District (EBMUD) as they ascend the fish ladder at Woodbridge Dam. As of January 16, a total of 7,191 Chinook have passed upstream of the dam this season (Figure 15).

During the reporting period, flow in the San Joaquin River at Vernalis declined from 17,213 cfs to 10,879 (Figure 16). Most of the variations in flow occurred due to releases from Friant Dam (SJF), which were increased in December for flood control. During the reporting period, flows from Friant Dam were decreased from 6,980 to 1,770. Water temperature in the San Joaquin River ranged from 45.5�F to 49.1�F at Vernalis, from 46.1�F to 49.6�F at Mossdale, and from 46.7�F to 49.5�F at Rough 'n Ready Island (Figure 17). Average daily dissolved oxygen (DO) in the San Joaquin River fluctuated from 8.9 mg/L to 9.4 mg/L in the deep water ship channel (measured at Rough 'n Ready Island), and between 9.0 mg/L and 9.5 mg/L at Mossdale (Figure 18).