
The Delta smelt, Hypomesus transpacificus, a 2 to 3 inch native fish listed under both federal and state Endangered Species Acts, is found only in the Delta estuary. It is regarded as an indicator species, a fish that demonstrates the health of the entire Delta ecosystem.
Once the most abundant fish in the entire estuary, the population has collapsed to the point where not one fish was found in the 2018 Fall Midwater Trawl survey. The 2018 abundance index, a relative measure of abundance, is the lowest in FMWT history.
“No Delta Smelt were collected from any station during our survey months of September- December,” wrote James White, environmental scientist for the CDFW’s Bay Delta Region.
This is not the only survey of Delta smelt populations that the CDFW conducts, and the other assessments have found smelt, although in alarmingly low numbers.
"While this survey did not catch any Delta Smelt, it does not mean they are not present. Spring Kodiak Trawl survey caught 5 Delta Smelt in December," White noted.
White also said another survey, the Enhanced Delta Smelt Monitoring survey, caught 13 Delta Smelt during December.
While decades of water exports and environmental degradation under previous governors and federal administrations have brought the smelt, once the most abundant fish in the Delta, to the edge of extinction, Governor Jerry Brown and his administration did nothing to reverse the trend, according to fishermen and environmentalists.
Before this fall, the 2017 abundance index was the lowest in FMWT history. Only 2 Delta smelt were collected at index stations in the survey during the fall of 2017.
The Delta smelt is not the only fish not found during the fall 2018 survey. The CDFW didn’t observe any Sacramento splittail, a native minnow species that was formerly listed under the Endangered Species Act.