
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 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