The decline of the Striped Bass in the Central Valley
by Tom Cannon / thomascannon0@gmail.com
Striped bass are one of the most popular gamefish in California because of their large size, abundance, eating quality, wariness, fighting ability and voracity in taking lures and bait. Like the salmon and steelhead, striped bass numbers in California have declined sharply over the past 50 years. Despite these parallel declines, the striped bass have become the red herring of California’s water wars.
The decline of striped bass is generally associated with the startup of the State Water Project in the mid- 1970s in concert with the 1976-77 drought and a subsequent general acceleration of drought frequency. Adult striped bass population numbers fell from several million in the 1960s and 1970s to several hundred thousand in the 1980s; they eventually received protection and enhancement under the Central Valley Project Improvement Act (CVPIA) in 1992 and State Water Board water quality standards issued in 1978 (D-1485) and 1999 (D-1641).
D-1641, which was adopted by the SWRCB December 29, 1999 and revised on March 15, 2000, is the implementation plan for the 1995 Bay-Delta Plan, with respect to the operation of water projects within the Delta watershed. D-1641 includes water right permit terms and conditions to implement water quality objectives to protect Municipal and Industrial (M&I) beneficial uses in the Delta, as well as water quality objectives to protect Fish and Wildlife beneficial uses. D-1641 contains flow and water quality objectives that must be measured at various compliance monitoring stations throughout the Delta. (Mavens Notebook)
Striped bass became the “canary in the coal mine” for the Bay-Delta ecosystem, a harbinger of general decline driven by the exploitation of Bay-Delta water resources over the course of 70 years. The real problems started when the Central Valley Project’s Tracy Pumping Plant (TPP) began operating in the South Delta. South Delta exports were expanded (tripled from the 4,000 cfs transported by the TPP) in the 1970s when the State Water Project’s Byron Pumping Plant came online. Millions of juvenile striped bass were salvaged at the pumping plants each year through the mid-1970s; that continued until the State Water Board’s restrictions on exports began in 1978. The U.S. Army Corps of Engineer’s restrictions to minimize the pumping effect on Delta levees also helped to limit the SWP pumping capacity from 12,000 cfs to 8,000 cfs. Due to these restrictions, summer-fall exports were generally limited to 11,400 cfs from a capacity of almost 15,000 cfs. Winter-spring exports were increasingly restricted to protect listed salmon and steelhead, developments that also benefitted striped bass. Restrictions on exports and releases of millions of hatchery-raised striped bass helped to restore the striped bass population to approximately one million adults around the turn of the century. However, over the past two decades the population has again declined (additional details follow in this chapter).
Striped bass have also been blamed for the declines in salmon and steelhead populations1. Because of their popularity – and reputation for voracity – striped bass remain a key factor in Central Valley water politics.
