Actions to save fish may be killing other fish, which points to the uncertainty of the science used to make policy decisions, and also points to taking more time.
An excerpt.
Posted on Wed, Oct. 25, 2006
Scientist says timing affects fish
Research into decline of Delta says that changes to pumps in effort to help save salmon could be hurting other marine life
By Mike TaugherCONTRA COSTA TIMES
SACRAMENTO - The latest round of research into what caused a severe ecological crisis in the Delta suggests massive pumps that deliver water across the state could be playing an important role, but in ways much more subtle than usually considered.
If borne out, the research could force water managers to adjust, perhaps dramatically, the timing or amount of water pumped out of the Delta to millions of acres of farms in the San Joaquin Valley and to 23 million Californians from the East Bay to Southern California.
In one of the most intriguing pieces of research unveiled Tuesday during a three-day science conference on Delta programs and issues, a leading expert on Delta smelt presented findings that show the pumps could be killing fish that would otherwise have the best chance of surviving in a deteriorating Delta environment.
William Bennett of the Center for Watershed Sciences & Bodega Marine Laboratory said the fittest fish are the ones that hatch earliest in the year, and shifts in the timing of Delta pumping meant to protect salmon and other fish have resulted in the pumps running harder in the early spring when the larvae are near.
"The current management schedule, with the best intentions, has been pumping the most when the larvae are the most vulnerable," Bennett said.
By itself, that shift might not have done much harm. But deteriorating conditions in the Delta make it harder for the smelt to survive to adulthood, and the combination of weaker fish and a degraded Delta could go a long way toward explaining the smelt's crisis.
"It's like you're playing with your minor league baseball team," said Bennett, who said that until recently he doubted the pumps played a primary role in the fish crisis. "It's the combined effect," he added. "Populations are rarely affected by one thing."
Almost immediately after the collapse in populations of Delta smelt, longfin smelt, threadfin shad and young-of-the-year striped bass was confirmed in early 2005, scientists said the crisis likely was caused by some combination of water delivery operations, pesticides or other toxic materials and invasive species.
Roughly 18 months into their investigation, scientists still cannot say exactly what caused the populations to plummet beginning about 2001. But they said they are getting closer.
