Key Highlights

2007 Adult Migration Monitoring

2007/08 Juvenile Migration Monitoring

San Joaquin River Conditions

Delta Exports

December 3 -December 16, 2007

Key Highlights:

2007 Adult Migration Monitoring. Adult monitoring and carcass surveys are winding down in the Central Valley rivers, and low fall-run Chinook escapements are being observed in both the Sacramento and San Joaquin basins. Preliminary fall-run estimates in the San Joaquin Basin range from 167 (Tuolumne) to 429 (Merced), while estimates on the Yuba are less than 400 adults. Battle Creek fall-run estimates are higher than other tributaries at 20,000 to 25,000, but are down from Battle Creek escapement estimates for the past three years (i.e., 77,510 in 2006; 165,259 in 2005; and 92,093 in 2004). Five years earlier (2002), a record 463,296 fall-run Chinook returned to Battle Creek.

2007/08 Juvenile Migration Monitoring. The Shelton Road rotary screw trap on the Calaveras River resumed sampling on December 7. Daily O. mykiss catch increased during the sampling period, and a total of 89 juveniles and one adult were captured. Five fish were rated as smolts with about an equal number of parr and silvery parr making up the remainder of juveniles captured.

San Joaquin River Conditions. San Joaquin River flows increased by approximately 200 cfs following a rain event on December 6-7 before returning to flows near 1,350 cfs. Water temperatures continued to decrease during this reporting period as a result of cooler ambient air temperatures. Dissolved oxygen (DO) at Mossdale remained constant while DO in the deep water ship channel improved during the sampling period and averaged 8.5 mg/L.

Delta Exports. Combined exports ranged from 5,804 cfs to 9,694 cfs during the reporting period. Export rates at both the state and federal pumping facilities increased during the reporting period, each averaging almost 4,000 cfs.

We encourage subscribers to contribute any relevant information for future issues of the newsletter (e.g., additional monitoring studies, announcements of upcoming meetings and events, etc). If you would like to contribute, please contact Chrissy Sonke. If you have any questions please contact Doug Demko at 530-342-9262 or by e-mail at dougdemko@fishbio.com.

Upcoming Events

Jan. 17 : SRFG Meeting
Jan. 23: CRWSG Meeting

Featured Links

California Fish Website

Related Links

Tuolumne River Technical Advisory Committee
Calaveras River Fish Group
Stanislaus River Fish Group
San Joaquin River Group Authority
San Joaquin River Management Program

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2007 Adult Migration Monitoring

Central Valley Escapement:

2007 fall-run Chinook escapement throughout the West Coast is significantly lower than pre-season projections, especially in the Central Valley. Preliminary fall-run Chinook escapement estimates in the San Joaquin Basin (calculated using adjusted Petersen based on 11 weeks of carcass surveys) range from 167 (Tuolumne) to 429 (Merced). Similarly low numbers have been recorded in the Yuba River (i.e., less than 400). Yuba River fall-run escapement is down from last year when 3,457 Chinook were observed but is comparable to escapement in 2004. In Battle Creek, approximately 20,000 to 25,000 fall-run Chinook returned this year compared to 77,510 in 2006, 165,259 in 2005, and 92,093 in 2004. Five years earlier (2002), a record 463,296 fall-run Chinook returned to Battle Creek. Even though Battle Creek returns were low this year, the Coleman National Fish Hatchery was able to meet its spawning goals by taking in 10,000 Chinook which corresponds to about 12 million salmon that will be released in April 2008. The final number of fall spawners in most of the Central Valley rivers will not be available until carcass surveys are complete at the end of this year.

In the Yuba River escapement of other Chinook salmon races (i.e., late fall-run and spring-run) and steelhead have increased slightly during the last few years. In 2007, 113 late-fall run Chinook returned compared to 22 in 2006, five in 2005, and 16 in 2004. Similarly, spring-run returns have also shown an improvement with 153 returning in 2007 compared to 2 returns in 2006 and 53 in 2004. Steelhead numbers have increased as well with more than 500 returning this year compared to 150 returning in 2006.

Stanislaus River Weir:

Between December 3 and December 16, only 17 Chinook were recorded passing upstream of the weir, increasing the season total to 400. Daily upstream passage ranged from zero to four Chinook. The last Chinook recorded passing upstream of the weir was on December 12. Zero adipose fin clipped Chinook and zero O. mykiss were detected during the sampling period. Monitoring will likely conclude at the end of December if passage continues to be zero.

One trapping period occurred on December 7 following a rain event which resulted in turbidity greater than 3.0 NTU. One female Chinook (810 mm FL) was captured increasing the total number captured this season to 24. The trap was re-opened as soon as turbidity levels decreased below 3.0 NTU.

During the sampling period, releases from Goodwin Dam (GDW; RM 58.4) remained consistent and ranged between 280 cfs and 286 cfs; flow at Orange Blossom Bridge (OBB; RM 46.9) ranged between 185 cfs and 314 cfs; and flow at Ripon (RIP; RM 15.7) ranged between 292 cfs and 344 cfs. Turbidity at the weir site ranged from 0.46 NTU to 4.4 NTU and DO averaged 9.6 mg/L. DO downstream of the weir at Ripon (RPN; RM 15.7) ranged from 8.7 mg/L to 11.2 mg/L (avg: 10.2 mg/L). Daily instantaneous water temperature at the Stanislaus River weir ranged from 46 ºF to 52 ºF (avg: 48.4 ºF).

Tributary Carcass Surveys:

Carcass surveys are winding down on the Stanislaus, Tuolumne and Merced rivers, and will conclude the week of December 24. The peak numbers of live fish and redds observed on all three tributaries was extremely low this year compared to past years. During eleven weeks of suveys, a peak count of 236 redds were observed on the Stanislaus, 107 redds on the Tuolumne, and 87 redds on the Merced. Very few tagged carcasses have been recovered on all three tributaries (i.e., one out of 21 on the Stanislaus, 16 out of 35 on the Tuolumne, and 24 out of 86 on the Merced).

Thirty-six female Chinook were spawned at the Merced River Hatchery (MRH) this year which is about 47% fewer than last year (i.e., 77 spawned in 2006). Last year, only 402,000 eggs were fertilized resulting in most of production reserved for in-river releases and only a minimal number of juveniles provided for San Joaquin Basin studies (i.e., only 1,000 study fish released in 2007 for VAMP's acoustic tag study and zero fish released for other studies such as tributary smolt survival studies, rotary screw trap efficiency releases, trawl efficiency releases, and VAMP smolt survival experiments). In 2007, approximately 300,000 coded-wire tagged (CWT) fish were released into the Merced River as part of the Merced River Smolt Survival Study (200,000 released at MRH and 100,000 at Hatfield State Park). Additionally, 8,000 MRH fish were marked and released in the Merced River for rotary screw trap efficiency releases near Hatfield State Park while the remaining 36,000 unmarked hatchery fish were released into the river at the MRH.

2007/08 Juvenile Migration Monitoring

The Calaveras River rotary screw trap at Shelton Road (RM 29) resumed sampling on December 7. Sampling did not occur between November 29 and December 6.

The trap sampled a total of eight out of ten days between December 7 and December 16. A total of 87 Age 1+ (greater than 100 mm), two young-of-year (YOY; less than or equal to 100 mm), and one adult (greater than 300 mm) O. mykiss were captured. Individual lengths of Age 1+ ranged from 105 mm to 218 mm (avg: 137 mm) and weights ranged from 12.7 g to 120.5 g (avg: 29.4 g). The two YOY O. mykiss were 96 mm and 99 mm and weighed 9.8 g and 10.6 g, respectively. The single adult O. mykiss was 311 mm and weighed 330.5 g. Very few of the O. mykiss captured were smolting (n=5) while the others were rated as a parr (n=54) or silvery parr (n=57). Note: Three O. mykiss were not rated. Parr are likely redistributing themselves into downstream habitat and not actively migrating. It is unknown whether silvery parr are actively migrating or redistributing into other habitats as they transition to the smolting stage.

Additionally, one Chinook (110 mm; 14.6 g) was captured during the sampling period (December 8) suggesting some Chinook spawning may have occurred last spring above Shelton Road.

Instantaneous temperature taken at the trap ranged from 43ºF and 49ºF, and turbidity ranged from 0.39 NTU to 1.62 NTU. Daily average flow at New Hogan Dam (NHG) fluctuated between 31 cfs to 54 cfs, and flows at Bellota (MRS) ranged between 6 cfs and 36 cfs.

San Joaquin River Conditions

During the reporting period, flow in the San Joaquin River at Vernalis ranged from 1,346 cfs to 1,564 cfs (avg: 1,445 cfs) with peak flows occurring temporarily following a rain event on December 6-7. Water temperatures in the San Joaquin River continued a steady decline that began in early September as a result of cooling ambient air temperatures. Water temperature in the San Joaquin ranged from 46.5 °F to 53.1 °F (avg: 49.7 °F) at Vernalis; from 47.2 °F to 53.5 °F (avg: 50.4°F) at Mossdale; and from 50.1 °F to 54.8 °F (avg: 52.1 °F) at Rough 'n Ready Island. Dissolved oxygen (DO) in the San Joaquin River at Mossdale fluctuated between 10.0 mg/L and 11.3 mg/L (avg: 10.7 mg/L). Meanwhile, DO in the deep water ship channel (measured at Rough 'n Ready Island) continued to improve since the last reporting period and fluctuated between 7.8 mg/L and 8.8 mg/L (avg: 8.5 mg/L).

Delta Exports

Mean daily pumping at the C.W. Jones Pumping Plant (federal pumps previously known as Tracy Pumping Plant) remained constant averaging approximately 3,700 cfs from December 3 through December 9. Pumping rates then increased by approximately 600 cfs for a five-day period before decreasing to 3,550 cfs by December 16. Mean daily pumping at the Harvey O. Banks Pumping Plant (state pumps) gradually increased from 2,313 cfs on December 3 to a peak of 5,973 cfs by December 9. Pumping rates ranged from 4,245 cfs to 4,974 cfs between December 10 and December 14, then decreased to 3,380 on December 16.

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Data Disclaimer:  The data displayed on the sanjoaquinbasin.com website are courtesy of Stockton East Water District (SEWD), California Department of Fish & Game (CDFG), U.S. Fish & Wildlife Service (USFWS), Tri-dam, Turlock Irrigation District (TID), Modesto Irrigation District (MID) and FISHBIO.  Data are intended to be current, but are preliminary and are not guaranteed to be accurate.  Source data compiled and provided by FISHBIO, from whom further information can be obtained.  Use or reproduction of this data is prohibited without prior permission of SEWD, CDFG, USFWS, Tri-dam, TID, MID and/or FISHBIO.