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Zero Delta Smelt found in CDFW fall survey from Sept. to Nov. as Delta Tunnel goes forward

by Dan Bacher
No Delta Smelt, once the most abundant fish on the Sacramento-San Joaquin River Delta, were collected in the CDFW's Fall Midwater Trawl survey from September through November.
sm_delta_smelt_by_metric_ruler_usfws.jpg
A Nov. 28 memo from James White, environmental scientist for the Bay Delta Region of the California Department of Fish and Wildlife (CDFW), reveals that zero Delta Smelt have been found in the CDFW’s fall midwater trawl survey (FMWT) on the Sacramento-San Joaquin River Delta.

If no Delta Smelt are reported in the survey this month, this would be the sixth year in a row that zero smelt have been been found in the FMWT.

The slender 2 to 3 inch fish, once the most abundant fish in the entire estuary, is found only in the California Delta. It is considered an indicator species that shows the relative health of the imperiled estuary. 

“No Delta Smelt were collected at any stations from September through November,” wrote White. “The 2022 September-November index (0) is tied with 2016 and 2018-2021 as the lowest index in FMWT history.” (Figure 2) 

Smelt said an absence of Delta Smelt catch in the FMWT is “consistent among other surveys in the estuary.” For example, the Enhanced Delta Smelt Monitoring (EDSM) survey of the U.S. Fish and Wildlife Service (USFWS) caught 6 Delta Smelt among 11 sampling weeks (between 9/6 & 11/17) comprised of 2,986 tows (U.S. Fish and Wildlife Service 2022).

The data on Delta Smelt and other fish species is available here on the annual state surveys webpage. You can find the memo in the bibliography section of the FMWT page.

The Delta smelt is now near-extinction in the wild, although U.C. Davis continues to raise the fish in a captive breeding program. Thousands of these hatchery-raised smelt were released into the Delta in an experiment late last year and early this year.

On December 14 and 15,  2021, the U.S. Fish and Wildlife Service and CDFW, along with the California Department of Water Resources and U.S. Bureau of Reclamation, experimentally released 12,800 hatchery-raised Delta smelt into the Delta for the first time. The agencies released another load of smelt in January and three more in early February.

Unfortunately, these fish don’t appear to have fared well in the estuary, based on the results of the latest FMWT and EDSM surveys. 

The numbers of Longfin Smelt, a cousin of the Delta smelt, continue to be very low, compared to historical numbers, but the 2022 September-November index (321) is a 31% increase from the previous year, said White.

“Five Longfin Smelt were collected at index stations in September for an index of 7. In October, 99 were collected for an index of 261. In November, 29 were collected for an index of 53. No Longfin Smelt were collected at non-index stations during the three-monthly surveys,” White reported.   

The U.S. Fish and Wildlife Service on October 6 proposed the listing of the San Francisco Bay-Delta distinct population segment of longfin smelt as an “endangered” species under the Endangered Species Act (ESA).   

”Scientific analysis shows the Bay-Delta longfin smelt is in danger of extinction throughout its range,” the service said in a statement. The Service is now seeking public comment for 60 days after publication on the proposed rule in the Federal Register.

Striped Bass, an introduced gamefish species that once numbered in the millions in the estuary, also continue to be found in dramatically low numbers in the surveys. The 2022 September-November index (55) is a 7% increase from the previous year, according to White.

“Nine age-0 Striped Bass were collected at index stations in September for an index of 10,” White wrote. “In October, 26 were collected for an index of 34. In November, 10 were collected for an index of 11. 4 Striped Bass were collected at non-index stations during September, 0 were collected in October, and 1 was collected in November.”

Threadfin Shad, an introduced forage fish that is a member of the herring family, continue to show in low numbers also. The 2022 September-November index (119) is a 4% decrease from the previous year.

“Six Threadfin Shad were collected at index stations in September for an index of 7,” stated White. “In October, 33 were collected for an index of 39. In November, 64 were collected for an index of 73. 495 Threadfin Shad were collected at non-index stations during September, 336 were collected in October, and 36 were collected in November.”

American Shad, an introduced gamefish that is also a member of the herring family, also continues to found in low numbers. However, the 2022 September-November index (463) is a 37% increase from the previous year.

“56 American Shad were collected at index stations in September for an index of 110. In October, 120 were collected for an index of 155. In November, 113 were collected for an index of 198. 55 American Shad were collected at non-index stations during September, 33 were collected in October, and 35 were collected in November,” wrote White.

No Sacramento Splittail, a member of the minnow family found only in Central Valley rivers and the Delta, were collected at index or non-index stations in September through November for an index of 0.

“The 2022 September-November index (0) is a continuation of low to zero catch in recent years (Figure 7),” wrote White. “The Splittail FMWT index tends to be low or zero except in relatively wet years, such as 2011, when age-0 fish tend to be abundant. FMWT operates in water >2 m deep, whereas Splittail, particularly age-0 fish, appear to primarily inhabit water <2 m deep (Sommer et al. 1997; Moyle et al. 2004).”  

The Delta Tunnel under the Sacramento-San Joaquin Delta being pushed by Governor Gavin Newsom would only make things worse for the Delta smelt, longfin smelt, other pelagic species, Chinook salmon and  steelhead, since it would divert massive amounts of water from the Sacramento River before it goes through the Delta.  

The Delta Counties Coalition and Delta Legislative Caucus held a Delta Tunnel meeting in the Sacramento River community of Hood on the evening of December 6 that drew approximately 110 people.  Not one person who spoke supported the Delta Tunnel.

View the video here, thanks to Gene Beley: https://youtube.com/watch?v=JVi6-Q6kfHA

Background:

The final results of CDFW’s four-month survey of pelagic (open water) fish species, conducted from September through mid-December, probably won’t be available until late December or early next year. Normally a report from the Department summarizing the results of the abundance indices (a relative measure of abundance) for the different fish species is released at that time.

I have been writing a summary of each month’s results, as made available, until the final report for the fourth month survey is published.    

The Delta smelt population has plummeted over the decades since the State Water Project began exporting Delta water to San Joaquin Valley growers in 1967.

While there are several factors that scientists pinpoint for the ecosystem collapse, including toxic chemicals, decreasing water quality and invasive species, no factors figure greater in the collapse than water diversions from Central Valley rivers and the export of massive quantities of state and federal project water from the Delta to San Joaquin Valley agribusiness interests like Stewart and Lynda Resnick, owners of the Wonderful Company, and the Westlands Water District.  

According to White, the Fall Midwater Trawl (FMWT) reports on the relative abundance and distribution of upper-estuary pelagic species including but not limited to Delta Smelt (Hypomesus transpacificus), age-0 Striped Bass (Morone saxatilis), Longfin Smelt (Spirinchus thaleichthys), Threadfin Shad (Dorosoma petenense), American Shad (Alosa sapidissima), and Splittail (Pogonichthys macrolepidotus),.

The FMWT samples 122 stations each month from September to December, and those stations range from San Pablo Bay upstream to Stockton on the San Joaquin River, to near Hood on the Sacramento River, and into Cache Slough and through the Sacramento River Deep Water Ship Channel (SRDWSC).
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