Delta Fish Populations Reach Record Low Levels

by Dan Bacher The abundance of Delta fish species documented in the California Department of Fish and Wildlife’s fall midwater trawl s...

by Dan Bacher

The abundance of Delta fish species documented in the California Department of Fish and Wildlife’s fall midwater trawl survey plummeted again in 2012, after a temporary increase among Delta smelt and other species in 2011.

This record low abundance was predicted by Thomas Cannon, a well-respected fishery biologist who testified on behalf of the California Sportfishing Protection Alliance at State Water Resources Control Board meetings in October and November, 2012.

The most alarming of all of the declines was for threadfin shad, a once abundant forage fish used for striped bass bait on the Sacramento-San Joaquin River Delta.

The threadfin shad reached a record low abundance level, an index of 41. The index is a relative measure of abundance by the California Department of Wildlife (CDFW), formerly the California Department of Fish and Game (CDFG).

By contrast, the threadfin shad index reached its highest level recorded, 15267, in 1997 and was 14401 in 2001. Last year the index was 228.

The American shad abundance was the second lowest ever recorded, 415, only exceeded by the record low of 346 in 1976, the first year of a record drought. By contrast, the record abundance was 9360 in 1972.

The Delta smelt, an indicator species found only in the Bay-Delta Estuary that is listed as "endangered" under the Endangered Species Act, reached the seventh lowest abundance on record. The index this year was 42, beginning its backward slide after temporarily increasing to an index of 342 last year.

Longfin smelt, a cousin of the Delta smelt, plummeted to its second lowest recorded abundance, an index of 61. This was only exceeded in 2007, when the index reached a record low of 13.

Striped bass, a popular sport fish that corporate agribusiness has blamed for salmon and Delta smelt declines to divert attention from the impact of Delta water exports on fish species, dropped to the seventh lowest index on record, 125. The abundance for striped bass was 19677 in 1967 when the species was at its historic high.

The Sacramento splittail, a fish formerly on the Endangered Species List that was delisted by the Bush administration, also had an alarming low index of 1, the second lowest on record. An abundance of 1 was also recorded in 1997, 2002, 2007 and 2009. The record low abundance of 0, when no splittail were recorded, was observed in 1977, 2008 and 2010.

The complete suvrvey is available here.

The decline was predicted: The Delta VISE

Thomas Cannon, fishery biologist, predicted the low abundance of Delta fish species during his power point presentation before the State Water Resources Control Board.

“I told the State Water Resources Control Board that the numbers in the 2012 fall survey would be really bad because of the Vise on the Delta, caused by increasing exports, increasing inflows and declining outflows,” said Thomas Cannon, fishery biologist.

Conditions similar to this spurred the Pelagic Organism Decline (POD) of Delta smelt, longfin smelt, striped bass and other species that state and federal scientists documented first in 2005.

The scientists pinpointed three major factors for the unprecedented decline (1) water export increases and changes; (2) toxic chemicals/ and (3) invasive species. They later added ammonia discharges as a factor in the collapse.

Cannnon said the “vise” of increasing exports, increasing inflows from upstream reservoirs and declining outflows results in less residency time of water in the Delta.

The habitat that all of the pelagic fish studied thrive in is “green water” – water that has had a chance to stay in the Delta long enough for it acquire a greenish hue because of the abundance of phyto plankton, according to Cannon. This plankton serves as the basis for the food chain that Delta smelt, threadfin shad and the other fish species thrive in.

“If water exports take all of the Delta water and the water is replaced with water from upstream reservoirs, the water doesn’t have a chance to ‘stew’ with plankton,” said Cannon. “The warm water coming downstream during the summer is lethal to the smelt. The cooler Delta water that smelt need water replaced with warm reservoir water, making conditions doubly bad for smelt.”

To avoid these fish population crashes from happening in the future, Cannon recommended that the Water Board develop specific standards for inflows, outflows and exports on the Delta, according to year type.

Mike Taugher, CDFW Communications Director, responded to the release of the fall survey numbers.

“The fall midwater trawl numbers are consistent with the depressed numbers we have seen for the last decade,” said Taugher. “Last year's rebound was nice but almost certainly due to wet conditions in 2011.”

CSPA slams regulators for violating the law

Bill Jennings, Executive Director of the California Sportfishing Protection Alliance, blasted state and federal agencies for allowing the Delta fish population crash to continue.

“Here we are seeing another disaster in the species studied in the fall midwater trawl surveys – and this was all predicted,” said Jennings. “Species are lurking on the edge of extinction and just about everybody in the regulating agencies is to blame.”

However, Jennings singled out the State Water Resources Control Board for its role in failing to stop the collapse.

“They have violated the Porter Cologne Act for 44 years and the Clean Water Act and Endangered Species Act for 40 years,” concluded Jennings. “These species declines are caused by a failure of the regulators to enforce and comply with the law.”

Record exports in 2011 led to record fish kill

While there was an upswing in Delta smelt and other species in the 2011 fall midwater trawl survey, it is important to understand that the Department of Fish and Wildlife and other agencies presided over record water exports to corporate agribusiness and Southern California in 2011, 6,520,000 acre-feet – 217,000 acre-feet more than the previous record of 6,303,000 acre-feet set in 2005.

These massive water exports resulted in the "salvage" of a record 9 million Sacramento splittail and over 2 million other fish including Central Valley salmon, steelhead, striped bass, largemouth bass, threadfin shad, white catfish and sturgeon.

An analysis by the Golden Gate Salmon Association (GGSA) has found that since year 2000 over one hundred million fish (102,856,027) have been sucked into the Delta pumps. This figure includes twenty six million valuable game fish, many of which are endangered. The massive loss of fish in these years is no surprise, since freshwater pumping from the Bay-Delta between 2000 and 2006 increased 20 percent in comparison to 1975-2000.

Salmon still on the brink

This massive carnage in the Delta pumps takes place every year in spite of the fact that the Central Valley Project Improvement Act, signed by President George H.W. Bush in the fall of 1992, set a goal of doubling the Bay-Delta watershed’s Chinook salmon runs from 495,000 to 990,000 wild adult fish by 2002. The legislation also mandated the doubling of other anadromous fish species, including Central Valley steelhead, white sturgeon, green sturgeon, striped bass and American shad, by 2002.

Rather than doubling, the Central Valley Chinook salmon fishery has suffered a dramatic collapse over the past decade, now standing at only 13 percent of the population goal required by federal law.

A NRDC and GGSA analysis, published in the Salmon Doubling Index in November 2012, reveals a steady decline in Bay-Delta Chinook salmon from 2003 through 2010, including a record low of 7 percent reached in 2009. The closest we ever got to meeting the salmon doubling goal was in 2002, when the index peaked at 64.33% of the doubling goal. (

Tom Cannon’s Conclusions:

1. Outflow criteria are too low in non-wet years and summer of wet years to protect Delta fishes, their food supply, and their low salinity zone habitat.

2. Export criteria expressed as Export to Inflow ratios do not protect Delta fishes, their food supply, and their low salinity zone habitat from being exported from the Delta.

3. Direct effects of low outflow and high exports also translate downstream into the Bay in the form of lower Bay inflow, less nutrients, fewer organisms, and reduced low salinity zone productivity.

4. Specific export and outflow criteria are needed to protect beneficial uses in the Bay and Delta.

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