The population of Delta Smelt plummeted to a new low in the annual spring survey conducted by the California Department of Fish and Wildlife (CDFW) as the endangered fish moves closer to the abyss of extinction.
The 2016 Spring Kodiak Trawl (SKT) index, a relative measure of abundance, is 1.8, a decrease from the 2015 index (13.8) and is the lowest index on record.
The small 2 to 3 inch fish, found only in the Sacramento-San Joaquin River Delta, is an indicator species that demonstrates the health of the estuary. As the Delta smelt declines, so do the other fish species found in the San Francisco Bay-Delta.
“This decrease was expected since the Delta Smelt population was at a record low at the end of 2015,” said Scott Wilson, Regional Manager of the CDFW Bay Delta Region, in a memo. “The SKT monitors the adult spawning stock of Delta Smelt, and this year’s low index means the number of spawners is also at a record low. This may limit larval recruitment and hinder their ability to recover in 2016.”
Only thirteen adult Delta Smelt were collected at 8 stations contributing to the index in 2016. “This is the lowest catch in SKT history, and a steep decline from the 2015 then-record-low catch of 88,” said Wilson.
Wilson said the annual adult Delta Smelt catch at index stations averages 311 fish and ranges from 13 to 948.
“Once the most abundant species in the estuary, we can now name smelt rather than count them,” said Bill Jennings, Executive Director of the California Sportfishing Protection Alliance (CSPA).
The Spring Kodiak Trawl began in 2002 and an index was first developed in 2012.
While state and federal managers often point to drought as the “cause” of the smelt’s decline, representatives of fishing groups believe it is due to decades of water exports and government mismanagement.
“The gross mismanagement of water by the state and federal governments has led to the demise of the Delta Smelt,” said Jennings. “The water projects are sending too much water south.”
For decades, the state and federal water projects have exported massive quantities of water south of the Delta to agribusiness interests on the west side of the San Joaquin Valley, Southern California water agencies and oil companies conducting fracking and other extreme oil extraction methods.
Jennings said the population may have already gone below the number of fish necessary to sustain the species.
Dr. Peter Moyle, UC Davis fishery scientist, professor and author, agrees.
”We are entering uncharted waters with the delta smelt now because populations have never been so low,” said Moyle. “My guess is that populations are so small now that random events, such as predation by a swarm of silversides on eggs and larvae in an isolated spawning event, can keep driving the population down.”
Likewise, Tom Cannon, estuarine fisheries ecologist and biostatistician, wrote on the California Fisheries Blog about the “poor prognosis” for Delta Smelt (http://calsport.org/fisheriesblog/?p=929).
“Since my last update in April, Delta and longfin smelt have continued their trends of record low numbers,” said Cannon. “I opined that they were not yet gone, but close, and that it remained to be seen whether the good conditions provided to date in 2016 could lead to some form of recovery for these two endangered species. The prognosis remains poor.”
Green and white sturgeon, which usually spawn in the Sacramento River in April and May, are also being decimated by the the current state and federal water management. For more information, go to Tom Cannon’s excellent article on the California Fisheries Blog: http://calsport.org/fisheriesblog/?p=938.
Ironically, Jennings pointed out that the State Water Resources Board is now preparing for upcoming hearings on the petitions by the Department of Water Resources and Bureau of Reclamation to change their points of diversion in order to proceed with the construction of Governor Jerry Brown’s Delta Tunnels, now renamed the California WaterFix.
“This plan will deprive the Delta smelt of their habitat by exporting vast quantities of water from the Sacramento River,” said Jennings. “If the State Board approves the petition, it will only exacerbate things enormously for the Delta smelt and other fish species.”
The Delta Tunnels plan will not only hasten the extinction of Delta smelt, but it will also drive longfin smelt, winter-run Chinook salmon, Central Valley steelhead, green sturgeon and other fish species closer and closer to extinction, according to Delta advocates and scientific experts. The California Water Fix will also imperil the salmon and steelhead populations on the Trinity and Klamath rivers, since water from the Trinity, the largest tributary of the Klamath, is diverted to the Sacramento River watershed through a tunnel in the Mountains from Trinity Lake to Whiskeytown Reservoir.
In addition, the State Board is also considering a request by the Sacramento Waste Water Treatment Plant to discharge up to 181,000 gallons of water per day that would raise the water temperature on the river and Delta, threatening smelt, salmon and other fish species, noted Jennings.
The Delta smelt collapse is part of an overall ecosystem decline driven by water diversions by the federal and state water projects, The CDFW’s 2015 Fall Midwater Trawl demonstrates that, since 1967, populations of striped bass, Delta smelt, longfin smelt, American shad, splittail and threadfin shad have declined by 99.7, 98.3, 99.9, 97.7, 98.5 and 93.7 percent, respectively, according to Jennings.