By Matt Weiser -- Bee Staff Writer
Tuesday, November 15, 2005
Researchers probing the decline of several fish species in the Sacramento-San Joaquin Delta say they will begin to focus on two culprits: more fish dying in winter at state and federal export pumps, and hostile conditions for fish in Suisun Bay.
These findings were offered Monday by a team of state and federal scientists. Their six-month research was prompted by alarming population declines first noticed last fall among threatened Delta smelt, striped bass and other fish.
The population crash which also affects threadfin shad and longfin smelt is considered by many to be a sign of a larger ecosystem crash in the Delta.
Implications are huge, because the Delta serves as water source for 5 million acres of farmland and 22 million people.
The export pumps have always killed fish, an unavoidable consequence called "entrainment," but nobody has clearly linked those fish deaths to population trends.
If the research eventually makes such a connection, it could result in changes to water project operations that could affect the state's economy.
But the scientists warned against drawing conclusions from their work so far.
"It's very difficult at this point to make recommendations to policymakers," said Mike Chotkowski, a member of the research team representing the U.S. Bureau of Reclamation. "What we're saying now is, we have this coincidence where entrainments are up, fish populations are down, and water exports are up."
Specifically, the data indicate that since 2000 more fish are being killed at the pumps during the winter season, between November and March.
This is especially worrisome because in the case of Delta smelt, longfin smelt and threadfin shad, these are adult fish preparing to spawn. So the loss of each fish represents the loss of hundreds or thousands of juvenile fish later in the year.
Bruce Herbold, a biologist with the U.S. Environmental Protection Agency, said about 30 percent more water has been exported in winter since 2000 than in prior years. This was done intentionally by state and federal water managers because too many fish were being killed at the pumps in spring and summer.
"It's a substantial increase, and we're looking at how that can change the hydrodynamics of the Delta," said Herbold. "Starting in 2003, the pumps took a remarkable density of smelt in light of the fact that there weren't that many smelt to be taken."
Herbold noted the entrainment data are not especially reliable. Yet the information still brought swift skepticism from water interests, indicating the high stakes.
"Until you put some quantitative numbers on these, it's misleading to me," said B.J. Miller, a Berkeley consultant for several major water contractors.
Understanding the increased fish kill at the pumps will be one major line of inquiry as the scientific team prepares a $3 million research plan for next year.
The second is that problems in Suisun Bay are harming survival of young fish.
Suisun Bay, between the confluence of the Sacramento and San Joaquin rivers and the Carquinez Bridge near Martinez, is considered an important nursery area for young fish, but the team's research shows it has become a melting pot for many problems affecting the Delta.
For instance, invasive species transported by ships' ballast water or dumped from home aquariums have affected the region.
The bay is also home to two major natural gas-fired power plants in Antioch and Pittsburg. The researchers have been unable to get operational data on the power plants from their owner, Mirant Delta LLC, which bought them from Pacific Gas and Electric Co.
But data from the 1970s show that the plants killed 86 million Delta smelt annually. The research team said there is no evidence the number has dropped
.
There are other water-quality problems.
A new class of pesticides, pyrethroids, has been adopted by farms and commercial pest-control firms in recent years. Considered favorable because they are less harmful to people and other mammals, it turns out pyrethroids are more harmful to fish.
Tina Swanson of the nonprofit Bay Institute, a frequent critic of the research effort, praised the presentation Monday, but said she wished the team had asked questions that might lead to immediate policy changes to help the imperiled fish.
"They haven't connected the dots yet, and we need to connect the dots," she said. "I hope that doesn't become an excuse for inaction, because that's what we did last year."
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