Delta smelt population plunges to new record low

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The population of Delta smelt, an indicator species that demonstrates the health of the Sacramento-San Joaquin River Delta, has declined to a new record low population level, according to the spring 2016 surveys conducted by the California Department of Fish and Wildlife (CDFW).

The January Kodiak Trawl survey produced only seven fish, while the February survey yielded just six smelt. The Delta smelt once numbered in the millions, but have plummeted after decades of Delta water exports, combined with the impacts of declining water quality and invasive species.

The delta smelt (Hypomesus transpacificus) is a small endangered fish, about 2.0 to 2.8 inches long, found only in the Sacramento-San Joaquin River Delta. It is nearly translucent, with a steely-blue sheen on the sides.

Carl Wilcox, CDFW policy advisor on the Delta, attributed the record low numbers of Delta smelt found in the January and February surveys to “the effects of the drought and low outflow conditions and the need to balance water project operations between between different species.”

“Exports from the Delta were very low, maintained for health and safety reasons, most of the time during the drought,” Wilcox noted. “The real issue was very low inflow, along with contingency plans to support the release of water from Shasta Dam for winter-run Chinook salmon. The water quality standards came at the cost of managing the cold water pool.”

Carl Wilcox is still optimistic about the potential survival of the Delta smelt, even though their numbers have reached record lows this year.

“Delta smelt are resilient and have the capacity to rebound even when at low levels,” he emphasized. “We have evidence that they’re in the system, are finding each other and they’re spawning. We’ve seen Delta smelt rebound whenever we’ve had good water conditions. The fish were on a downward spiral until 2011 until we saw an increase in abundance. The fish have experienced bad flow conditions ever since 2000.”

“The numbers are extremely low and we have a high level of concern,” added Wilcox. “We look at the Delta smelt from the perspective that they’re still out there and we’re still working to protect them. The management of the state and federal projects is constrained by the biological opinions for Delta smelt and winter-run Chinook salmon.”

Bill Jennings, Executive Director of the California Sportfishing Protection Alliance (CSPA), is much less optimistic about the survival of the Delta smelt, considering what he calls the “capture of the regulators by the regulated,” combined with the record low numbers of fish.

“Once the most abundant species in the estuary, we can now name smelt rather than count them,” quipped Jennings.

The Delta smelt collapse is part of an overall ecosystem decline driven by water diversions by the federal and state water projects, The CDFW’s 2015 Fall Midwater Trawl demonstrates that, since 1967, populations of striped bass, Delta smelt, longfin smelt, American shad, splittail and threadfin shad have declined by 99.7, 98.3, 99.9, 97.7, 98.5 and 93.7 percent, respectively, according to Jennings.

These percentage declines are reflective of the other 2015 surveys conducted by the CDFW, including the 20 mm, Smelt Larva, Spring Kodiak and the Summer Townet Surveys, noted Jennings. For example, the 2015 Townet Index for Delta smelt was “zero,” the lowest in the 56-year history of the survey.

“So far in 2016, survey results are even more dire,” said Jennings. “The first Spring Kodiak Trawl of Delta smelt showed a 67% decline from the record low of 2015 (which was 86% below 2014). The first Smelt Larva Survey found no Delta smelt (same as last year) and showed a 29.5% decline in Longfin smelt from 2015’s record low (which was 82% below 2014).”

The February 2016 Kodiak survey showed a 91 percent decline from the February 2015 survey, when 31 males and 37 females, a total of 68 smelt, were counted, according to Jennings. Only 2 females and 4 females were found in the February survey.

“We are getting to the point where the little boys and little girls are so few in number that they have a hard time finding one another,” said Jennings.

Jennings emphasized that “Mother Nature did not cause the estuary’s biological collapse,” in spite of claims by state and federal officials that the drought is the cause of the collapse.

“It is the result of illegal political decisions by state and federal regulatory agencies that have become captive to powerful special interests,” he stated.

He noted that these fisheries “evolved and prospered over thousands of years and survived the hundred-year mega droughts of the past.”

Since 1995, the Department of Water Resources (DWR) and US Bureau of Reclamation (USBR) have fully complied with Bay-Delta water quality objectives in only 8 of 21 years, according to Jennings. Yet the State Water Board has never taken an enforcement action for the thousands upon thousands of violations.

“In addition, the State Board has routinely waived compliance with legally promulgated criteria explicitly enacted to protect fisheries and water quality during critical drought sequences. And the fishery agencies have consistently acquiesced in these actions,” he said.

“We can attribute the collapse of the Delta smelt to the collapse of the regulatory agencies,” summed up Jennings.

Delta smelt are very near extinction in the wild – and Dr. Peter Moyle, UC Davis fisheries scientist, professor and author, is not not very optimistic either about their potential recovery.

”We are entering uncharted waters with the delta smelt now because populations have never been so low,” said Dr. Moyle. “My guess is that populations are so small now that random events, such as predation by a swarm of silversides on eggs and larvae in an isolated spawning event, can keep driving the population down.”

“These March rains are the best hope for any short-term recovery (as in 2011) because they should result in somewhat increased outflows from local run off in the Sacramento Valley, decreasing temperatures, increasing turbidity, diluting contaminants and other factors: all good for smelt,” said Moyle. “We are clearly close to extinction in the wild but whether we will see the last wild smelt in 2 years or 10 is anyone’s guess.”

“Presumably there is still a small probability of a miraculous recovery, but I am not optimistic, especially if we go back to drought conditions,” he concluded.

Endemic to the upper Sacramento-San Joaquin River Delta, the Delta smelt mainly inhabits the freshwater-saltwater mixing zone of the estuary, except during its spawning season, when it migrates upstream to freshwater following winter “first flush” flow events (around March to May). The smelt generally live only one year, although a small percentage of the population may sometimes survive to two years and spawn in one or both years. (

As Delta smelt populations near extinction, recreational, tribal and commercial salmon fishermen face restrictions this year, due to the low abundance estimates for Sacramento and Klamath River Chinook salmon.

As is the case with the Delta smelt, fish advocates say salmon populations have plummeted due to massive water exports out of the Sacramento-San Joaquin River system and the Trinity River, the largest tributary of the Klamath, along with poor management of northern California reservoirs by the state and federal governments and declining water quality. (

Rather than trying to restore these fish populations, the Brown administration appears to be moving in the opposite direction as the Governor promotes the California Water Fix to build the Delta Tunnels as a “legacy project.” The construction of the Delta Tunnels would hasten the extinction of Sacramento River winter-run Chinook salmon, Central Valley steelhead, Delta and longfin smelt, green sturgeon and other species, along with imperiling the salmon and steelhead populations of the Klamath and Trinity rivers.