[env-trinity] Decline In Delta Food Chain Alarms Scientists

[Daniel Bacher]

Decline In Delta Forage Species Alarms Scientists

by Dan Bacher

At first review, Central Valley fish populations appear to be on the road to 
recovery.

The estimated ocean abundance of Sacramento River fall chinook salmon this 
year is the highest ever recorded – nearly 1.7 million. Spring run and 
winter run salmon populations, although still a fraction of historical 
levels, are on a definite upswing.

The legal striped bass population, after plummeting because of years of 
decline, grew from 600,000 to over1.5 million fish between 1996 and 2001, 
according to the DFG.

And the white sturgeon population was estimated at 147,000 in 1997, while 
the current population is estimated at 80,000 with a present annual legal 
harvest rate of 5 percent, said Patrick Coulston, supervising biologist for 
DFG's Bay-Delta Branch. The population is regarded as “stable” by the DFG 
and is a far cry from the early 1900’s when the fish nearly become extinct 
in the Bay-delta estuary.

Yet amidst the positive signs among Central Valley game fish species, the 
Delta ecosystem appears to be in unprecedented trouble. “The Delta’s open 
water fish populations are mysteriously collapsing in a crisis that 
threatens the food web of the West Coast’s largest estuary,” stated Mike 
Taugher in his in-depth article, "Environmental Sirens in the Delta are 
Screaming,” in the Contra Costa Times on May 1.

Taugher’s story, featuring interviews with state and federal fishery 
biologists, makes the following alarming contentions.

• “Delta smelt, already a threatened species, fell last fall to the lowest 
level ever measured,” said Taugher.

• The juvenile striped bass population has also fallen to the lowest level 
recorded, according to the annual Department of Fish and Game surveys.

• “The key food source for small fish in the Delta, tiny organisms called 
copepods, a plummeting as well with numbers of a key species falling to 
extremely low levels,” he stated.

The article continues, “The rapid multiple declines could trigger measures 
that might affect water quality and supply from Contra Costa County to 
Southern California. Scientists say information in a number of different 
surveys of the Delta and Suisun Marsh revealed an ongoing, sweeping 
population crash that could not be explained by drought or any other easily 
identifiable cause.”

Randall Baxter, DFG Bay-Delta Program biologist, in a phone interview with 
me on May 11, confirmed the bad news about the Delta’s open water forage 
species, although he was not yet willing to describe it as a “population 
crash” before more research is done on the decline and its causes. The 
dramatic decline in open water species started about 3 years ago.

“The Delta smelt, threadfin shad, longfin smelt and juvenile striped bass 
numbers have dropped from low levels to even lower levels now,” he noted. 
“The populations have further diminished even though the water conditions 
have improved slightly.”

He is most perplexed that adult striped bass numbers remain relatively 
strong, according to DFG tagging studies, while the numbers documented in 
the annual juvenile surveys continue to plummet.

Nonetheless, he emphasized, “the copepods that sustain the food chain have 
declined to the lowest levels ever. Something really serious is going on in 
the Delta. We’re in the process of developing studies to narrow down the 
cause of these declines that we will implement in June.”

Baxter also explained that his surveys haven’t looked at the bottom 
(benthic) organisms and have concentrated on the large river channels and 
islands. “We haven’t looked at other areas like Discovery Bay or the 
Sacramento Deep water Channel,” he said.

Their surveys documenting the decline in threadfin shad have been backed by 
reports of sharp drops in fishing success among commercial threadfin shad 
fishermen. “The commercial guys are having to work much harder and longer to 
get bait for the shops,” he concluded.

There are three main factors that the DFG and federal government believe may 
be responsible for the alarming declines.

First, toxic chemicals, including pesticides and herbicides, may be having a 
big impact upon these forage species.

Second, introduced species, such as the Asian clam and feria densa (an 
aquatic plant), are believed to be impacting the food chain. Interestingly 
enough, the mitten crab population, after a population explosion in the late 
1990’s, has declined to much smaller numbers now.

Third, continuing exports of Delta water have changed the Delta hydrology 
and are providing poorer habitat for these open water fish and 
invertebrates.  Notably, the Delta pumps at Byron and Tracy exported water 
to the Westside Water District and Southern California at the second and 
third highest rates ever over the past two years!

Fisherman’s groups and environmental organizations quickly reacted to the 
news of the declines by blasting the state and federal governments for 
pushing plans for more exports at a time when the Delta forage species are 
in such bad shape.

“The truly estuarine species such as striped bass are being most impacted by 
the decline of the Delta food chain,” said John Beuttler, consultant for the 
California Sportfishing Protection Alliance and former executive director of 
United Anglers. “Yet the federal and state governments have abandoned 
striped bass restoration in favor of restoring ESA listed species like the 
winter run and spring run chinooks.”

The same is the case of the American shad, another fish that spends a lot of 
time in the estuary. “In spite of one good shad season, we haven’t had 
really good shad runs in years,” contended Beuttler.

In contrast, king salmon and steelhead spend a relatively short time in the 
Delta as they move down from the rivers to feed in the ocean.

Beuttler faults the Calfed Program for meeting its goals of shoring up 
levees and providing “reliable water sources” for farms and cities, but 
failing to accomplish its fish restoration goals.

“Hundreds of millions were spend to restore wetlands and riparian habitat,” 
he said. “However, with a change in administrations in Washington, the 
restoration program ran into a problem; the water contractors wanted 
virtually all of the water for themselves.”

The whole focus of the Calfed Program changed from trying to restore the 
ecosystem to focusing on developing more water storage facilities, including 
the proposed raising of Shasta Dam, building another dam on the San Joaquin 
River and constructing so-called South Delta “improvements.”

“We have consistently pointed out in CALFED and agency forums that export 
rates must be reduced, not increased, if the system’s food web is to be 
restored to a healthy productive capacity,” said Beuttler. “We pointed out 
more than a decade ago – and we’ve repeated it incessantly – that exporting 
some 60 percent of the estuary’s water and food web to points south has, 
beyond it’s annual deleterious impacts, cumulative affects which appeared to 
be driving this declining ecological productively to the brink.”

At the same time that biologists are documenting the decline of the Delta 
food chain, the CALFÉD leadership has made it known that the stalled South 
Delta Improvement Project is back on track with a draft environmental impact 
report due out in June. The project will increase diversion rates from 6,300 
cfs to 8,500 cfs. “If that goes well, increasing diversion rates to 10,000 
cfs and over looms over the ecosystem,” warned Beuttler.

“The theme of Calfed was ‘let’s get better together’,” said Beuttler. 
“However, under the current administrations in Washington and Sacramento, 
the only guys that are getting better together are the water contractors. 
Since we apparently can’t get better together, let’s at least figure how to 
remove the steam roller off our fisheries!”

House Democrats also reacted strongly to news of the decline. On May 12, 
Members of Congress from California and Arizona, led by Congressman George 
Miller (D-Martinez), called on state and federal agencies to explain their 
actions in the face of "drastic declines" in fish populations of the San 
Francisco Bay and Delta region, the west coast’s largest estuary.

With the alarming decline of open water species in the Delta being 
documented by scientists now, it is crucial that the federal and state 
governments immediately suspend all attempts to increase water exports. 
Unless the problems of the Delta are dealt with immediately, we can expect 
to see the gamefish recoveries of recent years flushed down the California 
Aqueduct and  Delta-Mendota Canal.