| Volume 2008/09, Issue 1 |
October 7, 2008 | |
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Oct. 22-24: CALFED Science Conference
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Key Highlights
2008 Adult Migration Monitoring. The Stanislaus River Weir was installed and monitoring began on September 9, 2008. Similar to reports from other watersheds, the Stanislaus Weir has recorded more fall-run Chinook salmon in September than expected. Central Valley Chinook salmon escapement is predicted to be below spawning goals this year resulting in the most restrictive salmon fisheries regulations in West Coast history. Both recreational and commercial ocean salmon seasons are closed for 2008.
2007 Adult Migration Review. For the San Joaquin Basin, the preliminary 2007 fall-run Chinook salmon escapement estimate is 1,195 individuals, which is the lowest escapement estimate since the 1987-1992 drought. Escapement estimates in individual tributaries for 2007 ranged from a low of 211 (Tuolumne River) to a high of 576 (Merced River).
San Joaquin River Conditions. San Joaquin River water temperatures and flow at Vernalis decreased while dissolved oxygen fluctuated during the reporting period.
Delta Exports. Combined total exports (state and federal pumps) exhibited an initial decrease from 6,409 cfs to 3,358 cfs, which was followed by relatively stable rates between 3,714 cfs and 4,850 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.
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2008 Adult Migration Monitoring
The Stanislaus River Weir was installed in the same location as past years, i.e., approximately two river miles downstream of Jacob Meyers Park (RM 31.4) near the town of Riverbank (Figure 1). Monitoring began immediately following installation on September 9 and will continue through the fall-run Chinook salmon migration season. This is the sixth consecutive year that fall-run Chinook salmon and steelhead migration will be monitored using an Alaskan weir and Vaki Riverwatcher (Vaki) fish counter (Figures 2 and 3).
Figure 1. The Stanislaus River weir.
A total of 115 Chinook were recorded by the Vaki as they passed upstream of the weir between September 9 and October 1. Daily passage ranged between zero and 16 Chinook. Passage for the month of September already accounts for 28.2% of the low 2007 season total which was 408 Chinook. The number observed so far this year is similar to numbers observed during the same period in 2005 and 2006 (Table 1).
 Figure 2. Photographs taken by the Vaki RiverWatcher as Chinook make an upstream passage through the Stanislaus River weir.
Figure 3. Silhouette images captured by the Vaki RiverWatcher infrared scanner technology as Chinook make an upstream passage through the Stanislaus River weir. Red image is typical of a male Chinook and the blue image is typical of a female Chinook.
Table 1. Annual fall-run Chinook passage prior to October 1 of each year.  A similar increase in salmon counts is being seen on the Sacramento River where 1,718 more fall-run Chinook salmon were counted at the Red Bluff Diversion Dam this year than last year during the same period according to a recent report in the San Francisco Chronicle. Also, Columbia River fishery managers have upgraded their 2008 fall-run Chinook return estimate and extended their fishing season (please visit http://www.cbbulletin.com/296192.aspx for more details).
Instantaneous water temperatures measured at the weir ranged between 63.0˚F and 68.0˚F (Figure 4), instantaneous turbidity ranged between 0.3 NTU and 0.9 NTU (Figure 5), and instantaneous dissolved oxygen ranged between 8.0 mg/L and 10.1 mg/L (Figure 6). Daily average water temperatures at Ripon (RPN; RM 15) ranged between 68.3˚F and 73.0˚F and dissolved oxygen was stable ranging between 8.1 mg/L and 8.6 mg/L (Figure 6).
Daily average flow in the Stanislaus River fluctuated between 102 cfs and 288 cfs at Goodwin Dam (GDW; RM 58.4), between 133 cfs and 277 cfs at Orange Blossom Bridge (OBB; RM 46.9), and between 152 cfs and 287 cfs at Ripon (RIP; RM 15) (Figure 7). Note: flows downstream of Goodwin Dam may be higher than dam releases due to irrigation returns.
Releases from Goodwin Dam are scheduled to begin increasing on October 8 as part of the annual fall attraction flow period. Fall attraction flows are intended to facilitate the upstream migration of adult Stanislaus River fall-run Chinook through the San Joaquin River mainstem and into the Stanislaus River. The duration and magnitude of the attraction flows vary depending on the amount of water available for fishery flows, but typically range from 700 to 1,100 cfs for five to 12 days. The target attraction flow this year is 850 cfs and will remain elevated for a 5-day period before decreasing to 250 cfs by October 23.
Figure 4. Daily upstream Chinook passage recorded at the Stanislaus River Weir in relation to instantaneous water temperature recorded at the weir and daily average water temperature recorded in the Stanislaus River at Ripon (RPN) and in the San Joaquin River at Vernalis (VER), Mossdale (MSD) and Rough & Ready (RRI), 2008.
Figure 5. Daily upstream Chinook passage recorded at the Stanislaus River Weir in relation to instantaneous turbidity recorded at the weir, 2008.
Figure 6. Daily upstream Chinook passage recorded at the Stanislaus River Weir in relation to instantaneous dissolved oxygen recorded at the weir and daily average dissolved oxygen recorded in the Stanislaus River at Ripon (RPN) and in the San Joaquin River at Mossdale (MSD) and Rough & Ready (RRI), 2008.
 Figure 7. Daily upstream Chinook passage recorded at the Stanislaus River Weir in relation to daily average flows (cfs) recorded in the Stanislaus River at Goodwin (GDW) and Ripon (RIP) and in the San Joaquin River at Vernalis (VNS), 2008. |
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2007 Adult Migration Review
Low counts of fall-run Chinook salmon throughout the Central Valley during 2007 resulted in unprecedented commercial and sport fishing closures along the Pacific coast. In the San Joaquin Basin, a total of 1,195 fall-run Chinook were estimated to have spawned, including 408 returning to the Stanislaus River, 211 returning to the Tuolumne River, and 576 returning to the Merced River (including Merced River Hatchery counts). This is the lowest San Joaquin Basin escapement estimated since the 1987-1992 drought (Figure 8).
The National Marine Fisheries Service (NMFS) suggests that poor ocean conditions were a major factor contributing to the low 2007 Sacramento River fall-run Chinook salmon (SRFC) abundance. Predictions are that SRFC spawning goals will not be met in 2008 so NMFS, the Pacific Fishery Management Council (PFMC), and the California Department of Fish and Game (CDFG) have adopted the most restrictive salmon fisheries regulations in West Coast history. Ocean fisheries are under a total closure between Cape Falcon, Oregon and the U.S.-Mexico border through April 30, 2009, and inland recreational fisheries for salmon are closed with a few exceptions.
For more information please visit:
http://www.pcouncil.org/newsreleases/PFMC_FINAL_PressRel.pdf http://www.dfg.ca.gov/news/issues/salmon/
Figure 8. Escapement estimates of fall-run Chinook in the San Joaquin Basin, 1957-2007. Source: Tri-Dam Project unpublished data (Stanislaus River Weir; 2003-2007), CDFG GrandTab database (CDFG carcass surveys except for Tuolumne 2005-2007), and CDFG Annual Escapement Survey Reports for Tuolumne River (CDFG Carcass Surveys for Tuolumne River 2005-2007). Merced River estimate includes hatchery spawned Chinook (1970-2007). CDFG = California Department of Fish and Game.
During 2007, thirty-six female Chinook were spawned at the Merced River Hatchery (MRH) yielding only 275,475 eggs available for fertilization. As a result, few juveniles were available for San Joaquin Basin studies (i.e., only 1,000 study fish released in 2008 for VAMP's acoustic tag study and zero fish released for other studies such as tributary smolt survival studies, and rotary screw trap and trawl efficiency releases).
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San Joaquin River Conditions
During the reporting period, flows in the San Joaquin River at Vernalis were initially relatively stable between 858 cfs and 1,011 cfs, and then began decreasing on September 17 to a low of 584 cfs by September 27 (Figure 9). Water temperatures in the San Joaquin River exhibited an overall decreasing trend with fluctuations between 69.9�F and 77.2�F at Vernalis; between 70.3�F and 78.1�F at Mossdale; and between 73.4�F and 78.5�F at Rough 'n Ready Island (Figure 10). Average daily dissolved oxygen (DO) in the San Joaquin River fluctuated between 5.6 mg/L and 8.5 mg/L in the deep water ship channel (measured at Rough 'n Ready Island) and fluctuated between 8.7 mg/L and 14.5 mg/L at Mossdale (Figure 11).
 Figure 9. San Joaquin River flow at Vernalis, water year 2008.
 Figure 10. San Joaquin River daily average water temperature at Vernalis, Mossdale, and Rough 'n Ready, water year 2008.
Figure 11. San Joaquin daily average dissolved oxygen at Mossdale and Rough 'n Ready, water year 2008.
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Delta Exports
Mean daily pumping at the C.W. Jones Pumping Plant (federal pumps previously known as Tracy Pumping Plant) fluctuated ranging between 2,817 cfs and 4,402 cfs (Figure 12). Mean daily pumping at the Harvey O. Banks Pumping Plant (state pumps) fluctuated ranging between 0 cfs and 2,037 cfs. Combined total exports (state and federal pumps) initially decreased from 6,409 cfs to 3,358 cfs, which was followed by relatively stable rates between 3,714 cfs and 4,850 cfs.
Figure 12. Daily exports at the Federal and State pumping stations, water year 2008.
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