“A total of 0 Wakasagi were collected at index stations and 16 from non-index stations. Monthly catch was highest in October and December, with catch being highest in SRDWSC among months,” White concluded.
The decline of Delta smelt and other pelagic fish species in recent years is part of the “Pelagic Organism Decline” (POD) that state and federal scientists first identified in 2005. The scientists attributed the decline to three major factors: changes in the Delta ecosystem spurred by water exports south of the Delta, the spread of invasive species and toxics in the water.
Between 1967 and 2020, the state’s Fall Midwater Trawl abundance indices for striped bass, Delta smelt, longfin smelt, American shad, splittail and threadfin shad have declined by 99.7, 100, 99.96, 67.9, 100, and 95 percent, respectively, reported Bill Jennings, Executive Director of the California Sportfishing Protection Alliance.
“Taken as five-year averages (1967-1971 vs. 2016-2020), the declines for striped bass, Delta smelt, longfin smelt, American shad, splittail and threadfin shad are 98.1, 99.8, 99.8, 26.2, 99.3 and 94.3 percent, respectively,” said Jennings.
Last year, scientists forecasted the likely extinction of Delta smelt in the wild in 2021or 2022. In January 10, Dr. Peter Moyle, Karrigan Börk, John Durand, T-C Hung, and Andrew L. Rypel, wrote on the California Water Blog a piece entitled, “ 2021: Is this the year that wild delta smelt become extinct?
“All signs point to the Delta smelt as disappearing from the wild this year, or, perhaps, 2022,” said Moyle. “In case you had forgotten, the Delta smelt is an attractive, translucent little fish that eats plankton, has a one-year life cycle, and smells like cucumbers. It was listed as a threatened species in 1993 and has continued to decline since then.”
The on November 14, 2021, California Sportfishing Protection Alliance (CSPA) fishery biologist Tom Cannon in his California Fisheries Blog revealed that two other surveys on the Delta had turned up similar results for the Delta smelt: calsport.org/...
“The Enhanced Delta Smelt Monitoring (EDSM) caught only 1 Delta smelt in 2200 smelt-targeted net tows in 2021,” wrote Cannon. “This compares to 49 captured in 2020 and hundreds in prior years. None were captured in the Spring Kodiak Trawl 2021 survey.”
“This year’s results indicate that Delta smelt are likely virtually extinct in the wild,” concluded Cannon.
I will be following the progress of the experimental reintroduction of hatchery-raised Delta smelt into the wild.
I am not optimistic about its success because of the dramatic changes in the Delta ecosystem that have been caused by water exports south of the Delta by the State Water Project and the Central Valley Project over the decades — combined with the impacts of invasive species, toxics, declining water quality and other factors — and the apparent unwillingness of the state and federal governments to make the necessary changes in their water export and dam operations that would save the Delta smelt and other fish populations.
Background:
“The California Department of Fish and Wildlife (CDFW) has conducted the Fall Midwater Trawl Survey (FMWT) to index the fall abundance of pelagic — open water fishes annually since 1967 (except 1974 and 1979). FMWT equipment and methods have remained consistent since the survey’s inception, allowing the indices to be compared across time. These relative abundance indices are not intended to approximate population sizes. However, we expect that our indices reflect general patterns in population change (Polansky et al. 2019).
In September, October, November, and December, 121, 122, 122, and 122 fish tows were conducted as well as 32 zooplankton tows, respectively. Here we report catch from index and non-index stations, species distributions by region, and annual abundance indices for seven pelagic fish species; Delta Smelt (native), Striped Bass (introduced), Longfin Smelt (native), American Shad (introduced), Threadfin Shad (introduced), Splittail (native), and Wakasagi (introduced).”