Zero Delta Smelt Found in CDFW Fall Midwater Trawl Survey Two Years in a Row

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Zero Delta smelt were found in the fall 2019 CDFW midwater trawl throughout the Delta. Photo by Dave Giordano.

The Delta smelt, once the most abundant species on the Sacramento-San Joaquin River Delta, continues its long slide towards extinction. For the second year in a row, the California Department of Fish and Wildlife in its annual fall midwater trawl survey in 2019 found zero Delta smelt during the months of September, October, November and December.

Found only in the San Francisco Bay-Delta Estuary, the smelt is an indicator species that shows the health of the ecosystem. Decades of water exports and environmental degradation under the state and federal governments have brought the smelt to the edge of extinction.

In spite of portraying their administrations as “green,” Governors Arnold Schwarzenegger, Jerry Brown and Gavin Newsom did nothing to reverse the slide towards extinction.

Meanwhile, the Trump administration recently finalized a plan that threatens the Delta smelt, salmon and other fish species even more than they already are by maximizing Delta water exports to corporate agribusiness interests in the San Joaquin Valley.

While the CDFW has not yet issued its annual memo analyzing the fall survey results, James White, CDFW Environmental Scientist, wrote in a memo about the September and October 2019 surveys:

“No Delta Smelt were collected at index stations in September or October. The 2019 September-October index (0) is tied with 2016 and 2018 as the lowest index in FMWT history (Figure 1). No Delta Smelt were collected at non-index stations during September or October,” said White.

A few smelt have turned up in other surveys on the Delta, but they also confirm the fish’s dramatic decline.

“This low index is consistent with sampling by other monitoring surveys in fall of 2019,” wrote White. “Delta Smelt were collected by USFWS Chipps Island Trawl in September (n=2) and not in October (n=0). USFWS Enhanced Delta Smelt Monitoring (EDSM) collected Delta Smelt in September (n=6) and October (n=7), having conducted 1,348 tows with catches in Suisun Bay, lower Sacramento River, and SRDWSC (data available at: USFWS Delta Juvenile Fish Monitoring Program).”

The fall 2019 survey also reported low numbers of Longfin Smelt and Sacramento splittail.

The abundance index for longfin smelt, a cousin of the Delta smelt, was only 44. That is down from an index of 52 in 2018 and 141 in 2017.

However, the indices for longfin smelt were well above the lowest abundance year for the longfin, 2015, when only 4 fish were reported and 2016, when only 7 fish were caught. In contrast, 81737 smelt were found in 1967.

For the second year in a row, the trawl caught zero Sacramento spittail, a native minnow found only in the Sacramento-San Joaquin River Delta just like the Delta smelt. With the exception of 2011 when 11 split tail were reported, the survey reported 0 to 1 fish each year over the past 13 years.

The index for young of the year striped bass, a popular gamefish introduced from the East Coast 140 years ago, was 250. This is better than last year when the abundance was 42, the lowest on record, but well below the fish’s historical abundance. By comparison, the index was 19,677 in 1967, the year the State Water Project pumps went into action.

The index for American shad was 1955, better than the index of 1064 last year. This contrasts with the record abundance in the 2003 survey, 9360.

Finally, the threadfin shad made a jump from 198 last year to 343 in 2019. However, both of these surveys were just a fraction of the 15267 shad counted in 1997.

The Delta smelt, Longfin smelt, Sacramento splittail, striped bass, American shad and thread fin shad are are all victims of the Pelagic Organism Decline, first coined by federal state and scientists to document the steep decline of pelagic (open water) fish and zooplankton in 2005. Scientists have pointed to Delta water export operations, toxics, invasive species and pollution as the key factors in this decline.

“Given the wet year we experienced in 2019, the numbers of Delta smelt, longfin smelt and splittail should have rebounded substantially, but instead it was another disastrous year for all three species,” said Bill Jennings, Executive Director/Chairman of the California Sportfishing Protection Alliance (CSPA). “Also given the wet year, striped bass, American shad and threadfin shad should have rebounded more than they did. Clearly, the state and federal Delta pumping operations are sending Delta fish species to the guillotine.”

In addition to the zero Delta smelt results of the fall 2018 and 2019 fall surveys, spring Delta smelt 20-mm surveys conducted in both 2018 and 2019 revealed a record low number of the smelt collected by Department scientists.

According to independent fisheries biologist Tom Cannon in his California Fisheries Blog on the California Sportfishing Protection Alliance (CSPA) website, the Late April and early May 20-mm Surveys “provide an excellent picture of the status of Delta smelt population in the estuary.”

“Since 2017, some surveys collected no Delta smelt (Figures 1-3) in the San Francisco Bay-Delta estuary. The 2018 and 2019 survey catches are a new low for Delta smelt, lower even than the 2017 survey catch and the lowest in the 1995-2019 survey period,” said Cannon.

“The outlook for the Delta smelt population remains grim after these lows. Despite good conditions in spring 2018 and 2019, the severely depressed number of adult spawners indicates a continuing weak potential for recovery,” Cannon concluded.

The 8 surveys conducted by the CDFW this spring produced a total of only 13 Delta smelt. Survey #1 yielded 2 smelt, survey #2 produced 1 smelt, survey #3 yielded 0 smelt, survey #4 produced 7 smelt, survey #5 yielded 1 smelt, survey #6 produced 1 smelt, survey #7 yielded 1 smelt, and survey 8 yielded 0 smelt.

While the water contractors blame the Delta smelt for restrictions on Delta pumping for San Joaquin Valley irrigators, findings published in the journal San Francisco Estuary & Watershed Science in March 2019 reveal that water exports from the South Delta were limited by infrastructure and water quality concerns far more often than protections for endangered species.

According to the article, during the 2010-2018 study period, 89% of Central Valley water flowing into San Francisco Bay was the result of salinity control and infrastructure constraints on water exports compared to less than 1.5% caused by endangered species act safeguards specific to protection of Delta smelt from entrainment in the export pumps.

“Safeguards for the San Francisco Bay estuary’s six endangered fish species led to relatively small increases in freshwater flow to the Bay,” said Greg Reis, staff scientist for The Bay Institute and lead author of the research article. “In two of the nine years, we studied, protections for Delta Smelt did not limit water exports for even a single day — the effect on water supplies of protecting this unique species, which functions as an indicator of overall ecosystem health, is far less than what’s commonly reported.”

“Despite water quality regulations that are intended to protect fisheries and wildlife populations in general, and endangered species act protections for the most imperiled fishes, the proportion of Central Valley river flows that make it all the way to San Francisco Bay has been declining for decades,” said Dr. Jonathan Rosenfield, Senior Scientist at San Francisco Baykeeper and co-author of this study. “Currently, Californians divert, on average, about 1/2 of the ecologically critical winter-spring runoff that would otherwise flow into San Francisco Bay, and the fish, wildlife, and water quality that rely on this water are suffering as a result.”

The prospects for the survival of Delta smelt, imperiled salmon and other fish species are grim unless the state and federal governments allow more quality water to flow into the San Francisco Bay-Delta ecosystem at critical times.

As Jennings said, “We know what fish need. Fish prosper when they have adequate flows and quality water. They suffer when they don’t. The question is how do we get them to survive on less water of poorer quality than they evolved with for thousands of years. The answer appears to be they can’t.”

”Delta Smelt are the thread that ties the Delta together with the river system,” summed up Caleen Sisk, Chief of the Winnemem Wintu Tribe. “We all should understand how that effects all the water systems in the state. They are the irreplaceable thread that holds the Delta system together with Chinook salmon.”