Principles of Salmonid Habitat Restoration
Several factors are critical to the recovery of endangered salmonids:
- Habitat protection – which includes such things as the preservation of intact stream corridors, or the conservation of vegetative cover in upslope areas.
- Effective watershed management – examples of which might involve the maintenance of natural fluvial-geomorphic processes, beneficial modifications to in-stream flows, or changes in the timing and quantity of water diversions.
- Education – including community and
policymaker outreach regarding the values of salmonids, requirements
for survival, and options for engaging in effective land stewardship.
- Habitat restoration – a relatively
new concept that has been defined in a variety of ways. The
Federal Interagency Stream Working Group (2000) defines restoration
as follows: Ecological restoration is the process of returning
an ecosystem as closely as possible to pre-disturbance conditions
and functions. Implicit in this definition is that ecosystems
are naturally dynamic... The restoration process reestablishes
the general structure, function, and dynamic but self-sustaining
behavior of the ecosystem.
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A native plant nursery in Santa Cruz County. Installation of genetically appropriate native plants is important for successful restoration projects.
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Effective restoration of salmon habitat requires rigorous multi-disciplinary
assessment and planning, and an adaptive approach to restoration
management. A distinguishing attribute of sustainable riparian
corridors in stream systems is the dynamic interaction between
hydro-geomorphic and biological processes
(see the Watersheds section of this Web site for more information).
Many alluvial stream reaches historically included a broad floodplain
gallery forest with backwater sloughs, oxbow lakes and floodplain
wetlands – all
of which contributed to the maintenance of water quality and
the sustainability of aquatic organisms, including salmonids.
The dynamic physical processes that created these features – such
as flooding and meandering – are the foundation for riparian
biodiversity and stream function. Therefore, the development
of criteria for sustainable riparian corridor protection, management,
restoration, and monitoring must include the documentation and
analysis of the hydro-geomorphic as well as the ecological processes
in a given watershed.
Because human and natural impacts can affect individual habitat
features as well as landscape scale processes, it is imperative
that restoration efforts be planned at the appropriate spatial
and temporal scale. In some cases, for example, relatively rapid
and site-specific habitat improvements – such as removing
a passage barrier or re-establishing riparian cover over the
stream – may be the extent of the restoration effort. In
other cases, the disruption of landscape scale processes is so
profound that site-specific habitat restoration efforts will
not be successful unless the underlying cause of the disturbance
is addressed – often a large scale, long term, prospect.
According to the Puget Sound Technical Recovery Team and Shared
Strategy Group (2000), "strategies
that emphasize the role of habitat forming processes and their
interconnections are most likely to result in the persistence
of aquatic habitat conditions necessary to sustain a salmonid
population."
In addition to taking place at multiple temporal and spatial
scales, restoration must account for the entire life history
of the target species, and address habitat improvements, habitat
diversification, and connectivity in the freshwater, estuarine,
and ocean environments.
The National Research Council (1992) outlines the following
steps for effective watershed restoration:
- Restore the natural sediment and water regime. Regime refers to at least two time scales; the daily-to-seasonal variation in water and sediment loads, and the annual to decadal patterns of flood and droughts.
- Restore the natural channel geometry, if restoration of the water and sediment regime alone does not.
- Restore the natural riparian plant community, which becomes a functioning part of the channel geometry and floodplain/riparian hydrology. This step is necessary only if the plant community does not restore (if not achieved via steps above).
- Restore native aquatic plants and animals, if they do not re-colonize on their own.
For detailed methods on implementing these steps, see the Implementation
of Restoration Projects section.
References
Federal Interagency Stream Restoration Working Group (FISRWG).
1998. "Stream Corridor Restoration: Principles, Processes,
and Practices." Federal Interagency Stream Restoration Working
Group (FISRWG). GPO Item No. 0120-A; SuDocs No. A 57.6/2:EN 3/PT.653.
ISBN-0-934213-59-3. View
on-line document.
National Research Council (NRC). 1992. "Restoration of
Aquatic Ecosystems: Science, Technology and Public Policy." Committee
on Restoration of Aquatic Systems. National Academy Press. View
on-line source.
Puget Sound Technical Recovery Team and Shared Strategy Staff
Group. 2002. "Puget Sound technical recovery planning for
listed salmon: Technical guidance for watershed groups in Puget
Sound (draft)."
Additional Resources
California
Department of Fish and Game's "California
Salmonid Stream Habitat Restoration Manual" Version 3,
1998.
Trout
Unlimited's "West Coast Salmon and Steelhead Protection
and Restoration Action Plan" 1997.
Other Relevant Links
Institute for Fisheries Resources
NOAA
Restoration Center
Pacific States Marine Fisheries Commission
Salmonid Restoration Federation
Society for Ecological Restoration
Trout
Unlimited – California
Watershed Management Council
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