Article from San Francisco Chronicle.
http://www.sfchronicle.com/science/article/Delta-smelt-on-the-brink-8153234.php
By Peter Fimrite
June 15, 2016
The fight to save the delta smelt, the beleaguered fish at the center of an increasingly bitter tug-of-war over water rights in the Sacramento-San Joaquin River Delta, is as close to a lost cause as ever, but fisheries biologists vow to continue the struggle to protect the species.
There are only about 13,000 endangered delta smelt remaining in the estuary this year, the lowest number in recorded history, according to estimates released last week by the U.S. Fish and Wildlife Service. It means a fish that for thousands of years could be found only in the delta is perilously close to extinction.
“It’s a very small number of fish,” said Steve Martarano, spokesman for the Bay-Delta office of the Fish and Wildlife Service. “They have a life cycle of about a year, so to have that low of a number in a body of water as large as the bay delta is very alarming.”
The population this year is well below last year’s estimate of 112,000 fish, the previous record low. Martarano said the yearly counts, which are extrapolations based on the state’s annual spring trawling surveys, go back to 2002, when there were 597,000 smelt.
Bad news in wet year
The fact that the recent drop-off happened during a relatively wet year, the kind that in previous years had prompted smelt populations to rebound, is troubling, said Peter Moyle, a professor of fish biology at UC Davis.
“Obviously, the drought hasn’t helped. It’s clearly made conditions worse,” said Moyle, who has studied the tiny fish for more than 40 years and is the foremost expert on the species. “But we had wet times this year and that should have delivered food and plankton. We would have expected delta smelt to do better in a year like this, but it doesn’t seem to have happened.”
The low numbers are particularly chilling, he said, given the cumulative decline over the past 30 years. The number of smelt, which were listed as endangered by the federal government in 2010, dipped below 500,000 for the first time in 2005 and remained below that 11 of the past 12 years. The exception was 2012, when the smelt population climbed to 623,000 following an extremely wet year, according to the department.
At stake is a 2- to 3-inch long fish that has adapted over eons to the shifting currents, brackish water and converging rivers in the vast 1,100-square-mile network of channels, islands and marshes known as the California Delta. There were once a million or more of the silver-colored fish in the delta and Suisun Marsh, by far the most plentiful fish in the region.
Year-long life span
Smelt swim only in bursts to get to locations where they can drift with the currents and feed, according to experts. They live for about a year, spawn and their larvae then drift down to Suisun Bay, where they grow and repeat the cycle.
They are, said Moyle, an “indicator species,” like the proverbial canary in the coal mine — a crucial gauge of the ecological health of the region. Their population nosedive is a signal that the delta ecosystem is not doing well, he said. Their absence diminishes the food supply for larger fish and birds.
“The entire delta has changed so much since they started diverting water that there has been a gradual change in the overall habitat,” Moyle said.
The smelt problem is both complicated and controversial. Environmentalists blame the vast federal and state water distribution system, which sucks water out of the delta and provides drinking and irrigation water for some 30 million Californians from the Bay Area, throughout the San Joaquin Valley and in Southern California.
Problem pumps?
They say the huge Tracy-area pumps suck in and kill smelt and even cause portions of the San Joaquin River to flow backward, confusing the migrating fish. Experts on smelt have long pushed for restoration of the tidal marshes and increased freshwater flows down the river.
The problem is that the water flowing into the delta is used to irrigate some 3 million acres of farmland, and the agricultural industry is more concerned about their crops than the fish.
The federal government enacted rules in 2008 that curtailed water exports during times of the year when delta smelt are spawning and larvae and juveniles are present. Agriculture industry representatives and politicians have since complained that farms are being starved of water to protect a “worthless minnow.”
Gov. Jerry Brown hoped his twin-tunnels plan would resolve the issue by skirting the delta, but the pipeline bypass has itself been mired in controversy.
And the delta’s signature minnow isn’t the only fish suffering as politicians and interest groups jockey for position at the front of the trough. The decline of the smelt follows an announcement by the National Marine Fisheries Service that 95 percent of the winter-run chinook hatchlings died last year in the Sacramento River, which was too warm to support them.
It was the second year in a row that millions of fish didn’t make it out of the river, which was plagued by a lack of snowmelt after four years of drought. Other fish, including longfin smelt, threadfin shad and the historic runs of adult chinook salmon, also are struggling, according to biologists.
Moyle said invasive predators have further depleted smelt populations. The overbite clam, which eats the plankton that smelt need, and the Mississippi silverside, which is a voracious predator of small fish, are just two of the aliens that have smitten the smelt, he said.
Especially vulnerable
The slumping smelt numbers this year can only mean that the regulations curtailing water deliveries and other efforts to save the fish haven’t worked. The fear now is that a pesticide spill or oxygen-sucking algae bloom that in the past wouldn’t have been a big deal could kill off all the remaining fish.
It is still possible to preserve the fish, Moyle said, but only if people stop bickering and come together to restore some of the ancient marsh habitat and develop water solutions that don’t involve more dams and pumping. Smelt are now being raised at the UC Davis Fish Conservation and Culture Laboratory, near Byron, where scientists hope to keep the species alive until the delta can be restored and the fish can be reintroduced.
“The situation I can’t say is completely hopeless. We do know that if you can create appropriate conditions in the delta they can survive,” Moyle said. “But with a downward trend like this, it is hard to be too optimistic about the long-term future.”