Delta danger; A decline in fish species and their food source is a reminder of a recurring worry in the West: A broad ecosystem collapse

Sacramento Bee - July 03, 2005
By Matt Weiser

Delta danger; A decline in fish species and their food source is a reminder of a recurring worry in the West: A broad ecosystem collapse

Sacramento Bee – 7/3/05

By Matt Weiser, staff writer

An unprecedented research effort is under way to make sense of an alarming plunge in several Delta fish species. But some observers worry it may be a case of "too little, too late."

The $2 million research plan was pulled together in just five months by state and federal officials after routine surveys in fall 2004 found sharp declines in populations of young striped bass and Delta smelt. The smelt is a threatened species under federal law, and an important indicator of the Delta's health because it lives for only one year.

Also declining is the threadfin shad, a non-native baitfish that has been abundant for years. All are known as "pelagic" fish because they inhabit the Delta's moving water column.

Perhaps even more worrisome, surveys also showed a simultaneous plunge in a key zooplankton at the roots of the food chain for these fish.

This revived a nightmare that has haunted the West's largest and most altered estuary: That it may have finally suffered a broad ecosystem collapse.

At stake is not just the fate of these fish and their habitat. Imperiled fish could lead to reduced water exports from the Delta that serve more than 20 million Californians and millions of acres of San Joaquin Valley farmland.

"When you see a whole group that lives together going down together, you've really got to wonder what's going on," said Chuck Armor, Bay-Delta operations manager for the state Department of Fish and Game. "And here we have a couple of our food organisms tanking, too. It's a bad situation."

At a meeting in Davis last week, fishing and conservation groups criticized officials for not doing enough to prevent the declines and not responding sooner. The fish populations actually began declining in 2001, reaching all-time lows last year.

An exasperated Roger Mammon, board member of the California Striped Bass Association, pointed to record water exports from the Delta as a likely culprit.

Pumping at state and federal water export facilities in the south part of the Delta reached record levels in three of the past five years. Mammon told state officials it's time for drastic measures, including rationing for south-state residents and farmers who benefit from the water.

"This excess pumping is not allowing the (water) flow to happen as God and nature intended," Mammon said. "I've been out there (fishing the Delta) 19 years now, and the changes are just unreal. How can you, in good conscience, kill this ecosystem?"

Fish and Game officials said isolating water exports as a cause of the fish declines would be a mistake. The Delta is so complex that several factors could be to blame, and research will focus on three areas: invasive species, water pollution, and water exports.

"I would love it if we could find a single smoking gun here. That would make my day," Armor said. "But it's not going to happen. This is going to be a tough one to tease apart."

Calling themselves the "POD Team," for "pelagic organism decline," state and federal scientists began their research with a statistical analysis of the fish surveys by an outside consultant. So far, it confirms that the declines are real and significant, said Ted Sommer, senior environmental scientist with the Department of Water Resources.

Over the summer, the team will examine virtually every aspect of fish life, including water pollution, the influence of water exports and changes in food supply. Researchers will dissect fish to look at spawning productivity and liver contamination. And they will use lasers to examine a fish ear bone called the otolith, which offers a window into how and where each fish grew to adulthood.

Never before, they say, has such a broad study of Delta fish been organized in such a short time. It will draw on $2 million contributed by the state Department of Water Resources and U.S. Bureau of Reclamation. Dozens of government researchers have been pulled off regular duties to work on the project.

The food chain will get particular scrutiny, and it offers a peek at the system's complexity.

For years, a key food for the threatened smelt has been a non-native zooplankton called Pseudodiaptomus forbesi. Basically a water bug about 1.5 mm long, it was first spotted in 1987 and probably arrived in a ship's ballast water.

In fall 2004, Pseudodiaptomus plunged to record lows along with the smelt, and biologists suspect yet another non-native is to blame: a type of algae called Microcystis aeruginosa. An even smaller link in the food chain, this algae looks like green corn flakes in the water, and it releases a deadly toxin. It also causes cancer in people and has even killed cattle that drink from infested stock tanks.

Looming over all this is the reality that these non-native species exist in the Delta only because it has been converted into an artificially fresh water system by export pumping, said Tina Swanson, a senior scientist at the nonprofit Bay Institute. If natural salinity levels existed under normal tidal action, the invaders would die.

"Should this trend continue, I think a number of species are incredibly vulnerable to extinction," Swanson said. "We need to look at the system far more holistically. I'm just not convinced this particular research is going to do that."

But Armor said a special "synthesis team" will do just that sort of holistic examination as part of the research. The project's results are to be presented to the public on Nov. 16. #
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