Delta's dying fish, toxic water may not be new phenomenon
The possibility that the crisis was triggered by problems that go back 20 years or more threatens to make solving the puzzling decline that much more difficult. Up until now, scientists have maintained that a steep and measurable collapse in the populations of several Delta fish species started about four years ago and was probably caused by a recent change in the way Delta water is managed and pumped out of the Delta, a recent invasion of a harmful species, new pollution or a combination of those factors. But independent scientists who reviewed research into the problem last year were unconvinced that some new factor is to blame. "The currently identified 'step-change' may simply be one of a series of such events," and researchers should not disregard two decades of declining fish populations while searching for a recent culprit, the scientists wrote. "The question of whether such a shift occurred -- or whether the apparent shift is simply part of the decline that has been occurring over decades -- is important," the report added. "The focus on a recent step-change has led to a search for causes and solutions in the immediate vicinity of the shift, while a focus on the historical decline would draw attention to long-term changes in the system." The report was requested by researchers to bring in outside review and advice. "I agree with that," said Chuck Armor, a manager in the California Department of Fish and Game and member of the team that has been investigating causes of the decline. "I think you will see us recasting some of our thinking to look at longer term things." Those long-term changes probably fall within the same categories researchers were already looking at -- water pumping, invasive species and contaminants -- just with broader scope. Another leading scientist in the original research effort said he remains convinced that the drop-off of fish populations beginning in about 2002 is important, but added that the review team might be correct in asserting that the problem could be deeper. "There may be an interaction between the long-term thing and more recent (events)," said Bruce Herbold, a U.S. Environmental Protection Agency biologist. "A lot of their message is to not lose sight of the long-term stressors." Herbold said state and federal agencies are crafting a response to the report, largely to seek clarification of some issues. A year ago, state biologists confirmed that populations of major fish species throughout the Delta's open waters had suddenly dropped beginning around 2002 for unexplained reasons. Despite favorable rain patterns in 2005, the crisis has not abated. The most seriously threatened fish, the tiny Delta smelt, plunged deeper toward extinction, according to surveys completed last month. A $1.7 million initial research effort was conducted last year to try to narrow down the list of possibilities that could be contributing to the decline, namely water diversions out of the Delta, contaminants and invasive species. Researchers also offered a pair of theories that might help explain the problem. One theory centers on an invasive clam species that could be depriving small fish of food sources in Suisun Bay; the second theory is focused on giant pumps near Tracy that have been running harder -- and killing more fish -- during the winter in recent years. "In six or eight months, it's not a bad start," said Tina Swanson, a scientist at the Bay Institute, an environmental research group. "But the point is this is the kind of work that should have started a decade ago." Armor, of the state Fish and Game Department, said he did not know why the decline of fish species was not more aggressively studied earlier. "Why wasn't someone on top of this years ago? I don't have an answer to that," Armor said. "The step decline ... got people's attention. That made it possible to start looking at this in great detail." The review of last year's research by nine outside scientists from universities and institutions around the country was generally complimentary, but it also contained several pointed criticisms. Specifically, the report said government agencies historically have failed to pay attention to contaminants in the Delta and that inattention is now hindering efforts to investigate pesticides and other contaminants as a possible cause for the Delta's ecological problems. The report also said it was surprising that no goals were spelled out to determine how healthy Delta fish populations should become as a result of restoration. "Restoration of any ecosystem requires a set of specific goals or targets in order to measure success or failure," the report said. And the scientists said it was surprising that state agencies had not collected data from the company that owns power plants in Antioch and Pittsburg to determine how many fish are killed by its water cooling systems. Mike Taugher covers natural resources. Reach him at 925-943-8257 or mtaugher@cctimes.comhttp://www.contracostatimes.com/mld/cctimes/13617437.htm 2006 ContraCostaTimes.com and wire service sources. All Rights Reserved.
|