DATE: Jan 12, 2021
SNIP: For the third year in a row, the California Department of Fish and Wildlife found zero Delta smelt in the agency’s 2020 Fall Midwater Trawl Survey throughout the Delta.
The 2- to 3-inch-long Delta smelt, found only in the Sacramento-San Joaquin Delta, is an indicator species that reveals the overall health of the San Francisco Bay-Delta Estuary. It was once the most abundant fish in the entire estuary, numbering in the millions. Now it’s on the verge of extinction in the wild.
“All signs point to the Delta smelt as disappearing from the wild this year, or, perhaps, 2022,” according to a California Water Blog post by Peter Moyle, Karrigan Börk, John Durand, T-C Hung and Andrew L. Rypel.
The Delta smelt collapse is part of an overall decline of pelagic (open water) fish species in the Delta that also includes striped bass, longfin smelt, Sacramento splittail, American shad and threadfin shad.
The survey samples 122 stations each month from September to December and a subset of these data is used to calculate an annual abundance “index,” a relative measure of abundance.
While there are many factors contributing to the fish’s decline, including toxics, invasive species and decreasing water quality, none is more key to the fish’s collapse than the changes in the Delta resulting from the giant state and federal water pumping facilities that have diverted water for decades to San Joaquin Valley agribusiness and Southern California water agencies.