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 Vol. 2, Issue 3: Nov. 9, 2007 |
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Key Highlights 2007 Stanislaus River Weir Monitoring Tributary Carcass Surveys San Joaquin River Conditions Delta Exports |
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Key Highlights:2007 Stanislaus River Weir Monitoring. Adult Chinook passage at the Stanislaus River weir slightly increased during the fall attraction period. However, passage remains consistently lower this year than during the past four years. Declines in Chinook escapement are being observed elsewhere throughout the Central Valley, as well as most of theWest Coast. Poor ocean conditions are speculated to be a primary cause. Tributary Carcass Surveys. Weekly carcass surveys began in the San Joaquin Basin tributaries the first week in October and will continue through December or early January. In comparison to the past couple of years, live fish counts and redd counts are significantly lower in the San Joaquin Basin tributaries as well as throughout the Central Valley adn the West Coast. San Joaquin River Conditions. San Joaquin River flow decreased to approximately 2,000 cfs at the end of October following the conclusion of the Stanislaus River fall attraction flows. Water temperatures continue to steadily decline in the San Joaquin River as they have been since September due to decreasing ambient air temperatures. Dissolved oxygen is averaging over 9.0 mg/L at both Mossdale and the deep water ship channel. Delta Exports. Combined pumping rates averaged approximately 6,700 cfs. Exports at the federal pumping facility have remained fairly constant since late June, whereas exports at the state pumping facility have decreased by nearly 4,000 cfs since the summer months. 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. To view a print version of this newsletter, click here. |
October 22-November 4, 2007 |
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Upcoming EventsNov. 14: VAMP Technical Team Meeting
Featured Links
Related LinksTuolumne River Technical Advisory Committee |
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2007 Stanislaus River Weir Monitoring Between October 22 and November 4, a total of 159 Chinook were recorded passing upstream of the weir, increasing the season total to 235. Daily upstream passage ranged from three to 32 Chinook. Weir passage during the sampling period included seven Chinook with clipped adipose fins (ad-clipped), increasing the season total of known hatchery fish to eight (3.4% of passage to date). To date, Chinook passage at the weir remains lower than recent years during the same period (17.1% of 1,374 observed in 2006, 11.4% of 1,904 observed in 2005, 9.4% of 2,232 observed in 2004, and 8.8% of 2,665 observed in 2003). Declines in Chinook escapement are being observed elsewhere in the Central Valley, as well as most of the West Coast. For example, only 54 Chinook were counted in the Yuba River during September compared to 909 counted during the same period last year. Similarly, fewer than 100 Chinook have been observed in the Russian River so far this year, compared to typical counts in the hundreds or thousands. Most scientists consider poor ocean conditions to potentially be the primary factor responsible for these low returns.
Trapping was suspended October 19-31 due to high flows associated with the fall attraction period. Subsequently, one trapping period occurred on November 1-2. A total of eight Chinook were trapped (three male and five female), increasing the season total to 15. Forklengths ranged from 805 mm to 940 mm (avg: 866 mm). Zero ad-clipped Chinook were captured during the trapping period. Releases from Goodwin Dam (GDW; RM 58.4) remained elevated (i.e., approximately 800 cfs) through October 31 as part of the annual fall attraction flow. 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. Following the conclusion of the fall attraction flow (i.e., October 31), releases from GDW were decreased to near 280 cfs. During the sampling period, releases from Goodwin Dam (GDW; RM 58.4) ranged between 284 cfs and 805 cfs; flow at Orange Blossom Bridge (OBB; RM 46.9) ranged between 221 cfs and 576 cfs; and flow at Ripon (RIP; RM 15.7) ranged between 320 cfs and 657 cfs. Turbidity at the weir site ranged from 0.65 NTU to 2.37 NTU and DO averaged 10.2 mg/L. DO downstream of the weir at Ripon (RPN; RM 15.7) ranged from 8.0 mg/L to 8.7 mg/L (avg: 8.4 mg/L). Daily instantaneous water temperature at the Stanislaus River weir ranged from 54.5 ºF to 58.0 ºF (avg: 55.6 ºF).
Tributary Carcass Surveys
The total number of redds observed during the five surveys combined was 31 redds on the Stanislaus River, 11 redds on the Tuolumne River; and zero redds on the Merced River. Typically, a peak in the number of redds observed occurs in mid to late-November. Please refer to Table 1 below for comparisons of redd and live counts to previous years. Table 1. Peak live count and total number of redds observed in the San Joaquin Basin tributaries through 5 weeks of carcass surveys from 2000-2007. Source: CDFG.
San Joaquin River Conditions
 
Delta Exports
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One 350 mm (TL) O. mykiss was recorded passing upstream of the weir on October 30, increasing the season total to two O. mykiss. The first O. mykiss detected this season (390 mm TL) was recorded entering the livebox and subsequently changing course to exit downstream on October 18. So far, this fish has not been recorded again. 
Adult fall-run Chinook carcass surveys began the first week of October on the Merced, Tuolumne, and Stanislaus Rivers. As of November 4, five weekly surveys have been completed with the most significant activity observed during week 5 (i.e., week of October 29). Although numbers are extremely low on all tributaries, the greatest number of live fish were observed on the Stanislaus River with a peak live count thus far of 47 Chinook. Peak live counts on the Tuolumne and Merced Rivers thus far were 29 and six, respectively. 
Flow in the San Joaquin River at Vernalis gradually increased from approximately 1,700 cfs to just over 2,300 cfs between October 22 and October 31 as a result of the abovementioned Stanislaus River fall attraction flow. Flows then decreased during the remainder of the reporting period to approximately 2,000 cfs. 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 59.9 °F to 62.8 °F (avg: 61.1 °F) at Vernalis; from 60.8 °F to 63.4 °F (avg: 62.0°F) at Mossdale; and from 62.9 °F to 64.2 °F (avg: 63.6 °F) at Rough 'n Ready Island. Dissolved oxygen (DO) in the San Joaquin River at Mossdale fluctuated between 8.7 mg/L and 9.7 mg/L (avg: 9.1 mg/L). DO in the deep water ship channel (measured at Rough 'n Ready Island) continued to improve and was similar to the DO recorded at Mossdale. DO in the deep water ship channel fluctuated between 8.7 mg/L and 10.4 mg/L (avg: 9.4 mg/L) during the reporting period. 
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© 2007 FISHBIO Environmental, LLC Data Disclaimer: The data displayed on the sanjoaquinbasin.com website are courtesy of 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 CDFG, USFWS, Tri-dam, TID, MID and/or FISHBIO. |