Aquatic Habitat Conservation

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A vital Habitat - An Iconic Species 

In the nineteenth century, the Columbia River was known as one of the greatest salmon producing rivers in the world with annual runs of 10 million to 16 million salmon. Today, 13 stocks of Pacific salmon and steelhead that traverse the lower Columbia River are considered threatened or endangered. Interior sloughs and the Mainland and Tenasillahe Island units could play a critical role in the survival and recovery of these listed stocks. These refuge units could provide food, refuge, and habitat for juvenile salmon during their transition, called smoltification, from fresh water to salt water. Improved quality and diversity of interior slough habitat in the estuary can directly influence the abundance and diversity of salmon populations that use the area. The lower Columbia River estuary has lost over 70 percent of its historical salmon habitat (50 percent since 1950), due primarily to construction of agricultural levees in floodplain habitat and to floodplain development. The importance of estuary sloughs in the life cycle of the Pacific salmon— the region’s iconic species—is well documented. Protection and restoration of sloughs is vital to the recovery of the region’s salmon and steelhead. Because these interior sloughs are managed by the refuge, the refuge can have a greater role in the assessment, monitoring, and management actions affecting aquatic habitat in the refuge’s sloughs.

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Scientific Data Leads the Way 

The Refuge, and its partners, assess, manage, and monitor aquatic habitat conditions and distribution of fish species, including biological characteristics; develop management activities to protect and restore habitats; and assess effects of implementing aquatic habitat management activities at the Mainland and Tenasillahe Island units and other areas where applicable. Including:

  • Conduct aquatic habitat and fish species surveys.
  • Modify existing tidegates to improve connectivity between the Columbia River and regulated sloughs.
  • Protect existing conditions of well-connected sloughs with high quality aquatic habitats for salmonids and other native species.
  • Eliminate barriers to fish passage within interconnected ditches and sloughs of the Mainland Unit.
  • Within small watersheds that cross the Mainland Unit develop agreements with landowners and local governments to conduct appropriate habitat restoration actions and improvements to fish passage.
  • Analyze data concerning physical habitats, riparian areas, and fish assemblages, to assess efficacy of aquatic habitat management activities especially relative to appropriate reference sites, and generate information to improve management actions and develop additional actions.

Learn more about science in the Refuge...