Anadromous Fish Restoration
Anadromous fish are freshwater fish that migrate to sea then return to spawn in freshwater.
In California, anadromous fish include coho salmon, Chinook salmon and steelhead. Those in the Central Valley have experienced significant declines from historical populations.
Of particular importance is the Chinook salmon as the species supports commercial fishing and related jobs and economic activities at fish hatcheries. The decline in salmon numbers is attributed to a variety of manmade and natural factors including drought, habitat destruction, water diversions, migratory obstacles created by local, state and federal water projects, over-fishing, unfavorable ocean conditions, pollution and introduced predator species. Wetlands have also been drained and diked; dams have blocked salmon and other anadromous fish from reaching historic spawning grounds.
Anadromous Fish Restoration
The Anadromous Fish Restoration Program, a part of the Central Valley Project Improvement Act, aims to double the natural production of fish that migrate between fresh water and salt water. The goal is to boost the numbers of salmon, steelhead, striped bass, American shad, white sturgeon and green sturgeon to at least twice the average levels attained during the period of 1967-1991.
Since 1995, AFRP has implemented more than 195 projects through funding by Congressional appropriations and a surcharge imposed on Central Valley Project water and power contractors.
Due to financial restraints, the AFRP has also developed priorities based on the watershed’s capacity to increase fish production. These priorities include:
- improving habitat by removing artificial barriers to migration
- installing or upgrading fish ladders
- expanding and improving the quality of spawning grounds
- acquiring permanent easements in floodplains and riparian corridors
Even so, anadromous fish populations continue to struggle for survival. Most notably, the West Coast salmon fishery collapsed in 2008. With the fish plummeting to record low numbers, federal officials closed all commercial and sport fishing off the coast of California and most of Oregon for a time, though recent good years have reopened such fishing.
In 2016 the National Marine Fisheries Service (NMFS) included the winter-run Chinook salmon as one of eight “Species in the Spotlight” among the most at risk for extinction in the near future. A five-year action plan states that “the survival and recovery of winter-run Chinook salmon cannot be achieved without establishing additional populations.”
Elsewhere for the endangered winter-run Chinook, such as along the Sacramento River and Battle Creek in Shasta County, improvement of fish passage and management of instream flows are needed to help to restore salmon and steelhead habitat. These efforts can help the anadromous fish navigate such migratory barriers as natural waterfalls, hydroelectric diversion dams, and weirs.
Habitat restoration is part of the Northern California Water Association’s suite of actions designed to help fish populations through its Sacramento Valley Salmon Recovery Program, a document founded on a 2011 report called Insights into the Problems, Progress and Potential Solutions for Sacramento River Basin Native Anadromous Fish Restoration.
“Instream habitat complexity is extremely important for fry and juvenile Chinook salmon and steelhead,” said the report, authored by fisheries scientist Dave Vogel. “Habitat complexity provided by instream structure such as large wood debris and large rocks or boulders provides young salmonids areas to rear and protection from predatory fish.”
In the future, climate change could impact habitat as water temperatures increase, water flows are decreased and flows altered. As a result, conditions necessary for anadromous fish survival will be more tenuous.