These three key strategies will help hatcheries deal with modern-day problems impacting salmon survival.
By Tim Scully, Special to CalMatters
Tim Scully is a graduate student specializing in California salmon restoration policy at the University of California, Santa Cruz, in the Coastal Science & Policy program.
We can no longer ignore that Central Valley Chinook salmon are on the edge of collapse.
Habitat loss and degradation, primarily from low river levels, make it necessary for hatcheries to support the vulnerable Chinook salmon population. State and federal hatcheries supply millions of baby salmon for release into the Central Valley and Sacramento-San Joaquin Delta to support commercial and recreational fisheries ranging from the Central Coast of California to the coast of Southern Oregon.
Restoration of in-river flows and salmon habitat is the long-term solution for returning salmon to their former glory. Still, hatcheries remain necessary until significant shifts in water and land management take place. Hatchery releases stave off the extinction of Chinook salmon and allow some of the West Coast’s most iconic fisheries to continue into the future.
The Central Valley’s hatcheries are essential in bolstering dwindling California salmon, but their aging infrastructure is ill-equipped to deal with modern-day problems impacting salmon survival. When state and federal hatcheries were first designed, the engineers did not consider the hatcheries’ adaptability to present-day stressors of climate change.
Additionally, Central Valley hatcheries were built to compensate for the loss of hundreds of miles of spawning habitat blocked by some of California’s largest dams, such as Shasta Dam and Oroville Dam. Central Valley hatcheries in the tributaries of the Delta are now also increasingly called upon to deal with problems downstream of the dams; a task for which they were never designed to address.
In our drought-stricken state, Central Valley hatcheries have resorted to transporting millions of baby salmon for release into San Francisco Bay, San Pablo Bay, Half Moon Bay and Monterey Bay to avoid treacherous conditions in the Delta and its tributaries. Bay releases are a lifeline to the ocean-based commercial and recreational fisheries, but they are also a testament to the severity of freshwater conditions upstream.
Fisheries rely upon hatcheries to continue these practices without additional resources or updated infrastructure, which is simply unsustainable.
Our hatcheries can adopt three key tools: genetic-based tagging, supplementation and trap-and-haul programs.
The success of these tools is evidenced by the Nez Perce Tribe and the Idaho Department of Fish and Game, which have utilized these tools to restore salmon-runs to their historical abundance and decrease negative influences of hatchery genetics on wild salmon populations.
Central Valley hatcheries should adopt genetic-based tagging, also known as parentage-based tagging, as an alternative to the often inefficient coded-wire tags that are currently used to keep track of salmon that originate in the Central Valley. Parentage-based tagging better informs salmon management decisions by providing extensive data on harvest estimates and genetic influence of hatchery salmon.
Supplementation involves imprinting and releasing baby salmon on prime spawning grounds so that they will return to these same grounds as adults instead of returning to their birth hatcheries. Supplementation increases natural reproduction, taking pressure off of the hatcheries to supply fish to the ecosystem. Supplementation requires parentage-based tagging to monitor its effectiveness.
Trap-and-haul programs, primarily used in the Pacific Northwest, involve transporting spawning adults around large dams, opening up hundreds of miles of historic spawning habitat that is currently blocked. This process also involves transporting out-migrating baby salmon to circumnavigate the dams on their way to the ocean.
The bottom line: Hatcheries in the Central Valley require increased funding and resources to adopt parentage-based tagging, supplementation and trap-and-haul programs to save salmon during our current drought and protect future populations from the droughts that are sure to follow.