
The Delta smelt has not yet become extinct, but the numbers of fish collected in the fall 2016 midwater trawl survey conducted by the California Department of Fish and Wildlife remain alarmingly low.
This is in spite of improved precipitation last winter and spring, followed by a wet fall that should have resulted in much higher numbers of smelt surviving.
The Delta smelt abundance index in the latest fall midwater trawl survey was 8, the second lowest in history. Seven Delta smelt were collected in November and none were collected in September, October, or December, according to a memo from James White, environmental scientist for the CDFW’s Bay Delta Region, to Scott Wilson, Regional Manager of the Bay Delta Region.
The small 2 to 3 inch fish, found only in the Sacramento-San Joaquin River Delta, is an indicator species that demonstrates the relative health of the largest estuary on the West Coast of the Americas. The species is listed under both the state and federal Endangered Species Acts. When the numbers of Delta smelt are so low, it reveals that the estuary, as we know it, is just as close to extinction as the fish themselves.
In 2015, the index was only 7. That was the lowest number recorded since the survey began in 1967, after the State Water Project began exporting water south of the Delta.
The numbers of smelt found this year and last contrast with 2011, a wet water year, when the Delta smelt index increased to 343, and then quickly plummeted again during the drought. Delta smelt abundance was highest in 1970 with an index of 1673 recorded.
Longfin smelt abundance is second lowest in survey history
The index for longfin smelt, a native species that is a cousin of the Delta smelt, was also dismal. The index was 7, the second lowest in fall midwater survey history.