Striped Bass and the Decline of the Delta
San Francisco Chronicle editor Lois Kazakoff blogged yesterday on a lawsuit by the Kern County Water Agency, which represents some of the state’s biggest agribusinesses to eliminate striped bass from California’s Sacramento-San Joaquin River Delta. As usual, great coverage of this issue comes from Mike Taugher at the Contra Costa Times, in a June 15 article, Striped Bass: Delta Villains?
Of course, big Ag water interests would like to shift attention away from the role of pumping and exports on the collapse of the Delta’s aquatic ecosystem. Time and again, they’ve tried to pin the blame for dwindling salmon runs on non-native species and inadequately treated sewage.
The truth is, there are multiple stressors: upstream diversions, pumping, pollution, and habitat destruction are ALL important. To preserve the health of the largest estuary on the west coast of the Americas, we need to address each one. A list of the fish that are threatened or endangered:
- Green Sturgeon
- Longfin Smelt
- Delta Smelt
- Splittail
- Fall-run Chinook Salmon
Eliminating pressure from exotic species may be among the things that we can get started on immediately. Installing proper fish screens at the outtakes and upgrading decades-old sewage plants will also help.
A National Research Council science committee, in its preliminary report, essentially said that there are a lot of different problems, and no one knows which is the most important, so we should probably try everything. Peter Moyle, a fisheries biologist at UC Davis, places the blame for the decline of native fish species on changes to the hydrology of the Delta. From the CC Times article:
The growing volume of water shipped out of the Delta changed its character. It became less of an estuary that could support salmon, smelt and striped bass and more of a freshwater system that favors largemouth bass, toxic blue-green algae, Brazilian water weed and exotic clams.
The change is largely due, indirectly, to the pumps that divert water to Kern County and elsewhere, Moyle said.
“The whole system has had a major shift,” Moyle said. “The ones that depend on the estuary — none of them are doing well.”
But none of these solve the problem until we begin to restore more of the natural volume and patterns of flow to the Delta. This graph shows how much freshwater flows into the Delta (from a presentation by the Bay Institute). In 2009, only 32% of runoff made its way to the Delta. The remainder was captured upstream for export to cities and farms around the state.
