The population of a tiny fish that lives near San Francisco Bay has hit an all-time low, a new study shows, troubling scientists who see it as an indicator of the health of the vast estuary.
SACRAMENTO, Calif. — The population of a tiny fish that lives near San Francisco Bay has hit an all-time low, a new study shows, troubling scientists who see it as an indicator of the health of the vast estuary that funnels water to two-thirds of Californians.
The population of the delta smelt in the Sacramento-San Joaquin Delta, an estuary east of San Francisco Bay, was just a third of what it was last year, according to the new state survey released Wednesday.
"The delta smelt last year was the lowest we'd ever seen, so this year is definitely the lowest," said Chuck Armor, a state Department of Fish and Game biologist who manages an ecological program that monitors the delta.
The population of another species, the longfin smelt, also is at a near-record low since measurements began in 1969, the survey found. Two other key fish species -- the threadfin shad and young striped bass -- had increases in the most recent survey, but still are far below historic levels.
Scientists are frustrated they have been unable to determine the cause of the declines in fish populations after a year of research. They had hoped to see a rebound, particularly because water conditions have been good.
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A new round of studies next year will be aimed at learning what caused the fish populations to fall, with a focus on the effects of water pumping and farming and invasive species such as a clam that is eating the fish's food.
Source: Associated Press
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