Figure 1. O. mykiss captured at the Calaveras River rotary screw trap.

The Calaveras River rotary screw trap at Shelton Road (RM 28) was operated sixteen days between January 31 and February 27, 2011. A total of 48 O. mykiss were captured during the reporting period, increasing the season total to 556 (Figure 1). Daily catches ranged between zero and seventeen individuals (Figure 2). All of the O. mykiss captured were Age 1+ (100-299 mm) and were rated as parr (n=4), silvery parr (n=38) or smolt (n=6). Average forklengths and weights of measured O. mykiss are provided in Table 1.

No Chinook salmon were captured during this reporting period.

Instantaneous temperature recorded at the trap ranged from 46.0�F to 51.6�F, and turbidity ranged from 0.56 NTU to 18.70 NTU. Daily average combined flows from New Hogan Dam (NHG) and Cosgrove Creek (COS) fluctuated between 29 cfs and 275 cfs, and at Bellota (MRS) flows fluctuated between 6 cfs and 1,419 cfs.

Table 1. Biosampling data for O. mykiss captured at Shelton Road between January 31 and February 27, 2011. Parentheses indicate range.

One trap efficiency experiment was conducted with naturally spawned Age 1+ O. mykiss marked caudal fin pink (CFP). The preliminary estimate of capture efficiency from the release was 41.2% at flows of 47 cfs from New Hogan (NHG) and 17 cfs at Cosgrove Creek (COS; Table 2).

Table 2. Trap efficiency test conducted at Shelton Road between January 31 and February 27, 2011.

The Stanislaus River rotary screw trap at Oakdale (RM 40) sampled continuously during the reporting period. A total of 28,872 juvenile Chinook salmon and 3 juvenile O. mykiss were captured, bringing the season totals to 39,685 and 10, respectively. Daily catch of Chinook salmon ranged between 28 and 5,693 individuals. Average forklengths and weights of Chinook salmon and O. mykiss are provided in Table 3 for the 1,759 Chinook and 3 O. mykiss that were measured. Most of the measured Chinook were fry (n=1,608), but parr (n=143) and smolts (n=8) were also recorded. The O. mykiss that were captured and measured were rated as smolts (n=3).

Figure 3. Marked Chinook salmon for Oakdale trap efficiency test a few minutes after marking. The majority of the green dye sloughs off during the 1 - 2 day holding period, such that only a faint mark is visible at the time of release.

Instantaneous temperature recorded at the trap ranged from 45.6�F to 51.9�F, and turbidity ranged from 0.29 NTU to 27.90 NTU (Figure 5). Daily average flow at Goodwin Dam (GDW) ranged between 201 cfs and 1,025 cfs, and flows at Ripon (RIP) ranged from 229 cfs to 958 cfs (Figure 4).

Six 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 are provided in Table 4.

Table 4. Trap efficiency tests conducted at Oakdale between January 31 and February 27, 2011.

Figure 4. Daily Chinook salmon catch at Oakdale and Stanislaus River flow recorded at Goodwin Dam (GDW) and Ripon (RIP), 2011.

Figure 5. Daily Chinook salmon catch at Oakdale in relation to instantaneous turbidity recorded at the trap, 2011.

The Stanislaus River rotary screw trap at Caswell State Park (RM 8) sampled continuously during the reporting period and a total of 240 juvenile Chinook salmon were captured increasing the season total to 355. Daily catch ranged between 0 and 81 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 46.9�F and 54.1�F, and turbidity ranged from 1.33 NTU to 12.40 NTU. Daily average flow at Ripon (RIP) ranged from to 229 cfs to 958 cfs.

Figure 6. Processing the Tuolumne River rotary screw trap at Waterford.

 

The Tuolumne River rotary screw trap at Waterford (RM 30) operated continuously during the reporting period (Figure 5). A total of 1,219 juvenile Chinook salmon fry were captured bringing the season total to 2,041. Daily catch ranged between 29 and 161 Chinook (Figure 6). Average forklengths and weights of all Chinook salmon are provided in Table 2. Most of the fry were buttoned up (n = 489), although a few sac-fry (n = 16) were also observed. 

Table 5. Biosampling data for Chinook salmon captured and measured at Waterford between January 17 and January 30, 2011. Parentheses indicate range.

No O. mykiss were captured during this reporting period. Instantaneous temperature taken at the trap ranged from 47.8�F to 50.9�F, and turbidity ranged from 1.01 NTU to 6.74 NTU. Daily average flow at La Grange (LGN) ranged from 1,580 cfs to 4,540 cfs.

Three trap efficiency experiments were conducted with naturally spawned juvenile Chinook salmon marked caudal fin green (CFO) during the reporting period. The preliminary capture efficiency estimates from the releases were 1.0%, 3.0% and 1.7% at flows of 1,610 cfs, 1,580 cfs and 2,450 cfs, respectively (Table 6).

Table 6. Trap efficiency tests conducted at Waterford between January 31 and February 27, 2011.

Figure 7. Daily Chinook salmon catch at Waterford, and Tuolumne River flow recorded at La Grange (LGN) and Modesto (MOD) between December 1, 2010, and February 27, 2011.

Figure 8. Chinook salmon captured and measured at Grayson.

The Tuolumne River rotary screw traps at Grayson (RM 5) sampled continuously during the reporting period and catch at Grayson continues to be higher than during the previous two years. A total of 496 Chinook salmon were captured, bringing the season total to 1,426 (Figure 8). Average forklengths and weights of all Chinook salmon are provided in Table 7. Most of the Chinook captured and measured were rated as fry (n=212), but parr (n=8) were also observed.

Table 7. Biosampling data for Chinook salmon captured and measured at Grayson between January 31 and February 27, 2011. Parentheses indicate range.

Instantaneous temperature taken at the trap ranged from 48.9�F to 52.5�F, and turbidity ranged from 1.62 NTU to 13.30 NTU. Daily average flows at Modesto (MOD) were not available for 13 days (Feb. 3 - Feb. 16) during the reporting period, but flows ranged from 1,640 cfs to 5,320 cfs during days that data were available (Figure 9).

No efficiency experiments were conducted during the reporting period.  

Figure 9. Daily Chinook salmon catch at Grayson, and Tuolumne River flow recorded at La Grange (LGN) and Modesto (MOD) between January 1 and February 27, 2011.

The Mokelumne River rotary screw trap at Vino Farms (RM 54) was sampled intermittently, and a total of 13,230 juvenile Chinook salmon were captured during the reporting period, bringing the season total to 23,487.

Average daily flow from Camanche Reservoir (CMN) remained stable between 601 cfs and 612 cfs (Figure 10). Instantaneous temperature ranged from 46.4�F to 49.6�F, and instantaneous turbidity ranged between 1.67 NTU and 5.16 NTU.

One young-of-the-year O. mykiss measuring 24 mm was captured on February 24, increasing the season total count to five.

Between January 31 and February 27 the Vaki Riverwatcher did not detect any Chinook salmon passing upstream of the Stanislaus River Weir. The season total remains at 1,382.

One O. mykiss (480 mm) was detected passing upstream on February 9 increasing the season total to four O. mykiss (Table 8).

Daily average flow in the Stanislaus River at Goodwin Dam (GDW; RM 58) fluctuated between 201 cfs and 1,025 cfs (Figure 12). Flow at Ripon (RIP; RM 15) ranged from 229 cfs to 958 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 47.6˚F and 53.7˚F, and daily average water temperature at Ripon (RPN; RM 15) ranged between 49.5˚F and 54.8˚F (Figure 13). Instantaneous turbidity ranged between 0.68 NTU and 30.40 NTU (Figure 14). Instantaneous dissolved oxygen at the weir ranged between 9.58 mg/L and 13.88 mg/L, and daily average dissolved oxygen at Ripon (RPN; RM 15) ranged from 8.78 mg/L to 10.85 mg/L (Figure 15).

Table 8. Net passage counts for all species between January 31 and February 27, 2011 at the Stanislaus River Weir.

Figure 12. 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.

Monitoring conducted by East Bay Municipal Utility District (EBMUD) at the Woodbridge Dam fish ladder on the Mokelumne River ended on February 1. A total of 7,196 Chinook salmon returning to the Mokelumne River this season (Figure 18).

During the reporting period, flow in the San Joaquin River at Vernalis increased from 6,771 cfs to 12,317 (Figure 19). Water temperature in the San Joaquin River ranged from 49.0�F to 52.0�F at Vernalis, from 49.7�F to 52.7�F at Mossdale, and from 50.0�F to 52.8�F at Rough 'n Ready Island (Figure 20). Average daily dissolved oxygen (DO) in the San Joaquin River fluctuated from 9.6 mg/L to 10.6 mg/L in the deep water ship channel (measured at Rough 'n Ready Island), and between 10.1 mg/L and 10.8 mg/L at Mossdale (Figure 21).

Mean daily pumping at the C.W. Jones Pumping Plant (federal pumps previously known as Tracy Pumping Plant) ranged between 1,923 cfs and 4,226 cfs (Figure 22). Mean daily pumping at the Harvey O. Banks Pumping Plant (state pumps) fluctuated between 4,392 cfs and 7,241 cfs. Combined total exports (state and federal pumps) during this period ranged from 8,178 cfs to 10,644 cfs.