Home	Overview	<Habitat>	Water Quality	Sedimentation	Flooding

 

	Habitat Loss Tillamook Bay and it's watershed have experienced habitat loss, degradation, and simplification that threaten anadromous salmonidpopulations. In past times, Tillamook Bay and the five rivers of its watershed supported large runs of salmon and steelhead trout. Of the five species once abundant in Tillamook waters, only fall chinook salmon populations are considered to be healthy and stable today (TBNEP 1998). Steelhead trout, sea-run cutthroat trout, coho salmon, and chum salmon have decreased dramatically since the turn of the century (TBNEP 2000). What Makes Healthy Salmonid Habitat? Healthy freshwater habitats for salmon are characterized by cool, clean well-oxygenated water; unobstructed access to spawning grounds; clean, stable spawning gravel; complex stream channels with riffles, glides, and deep pools; adequate large woody debris; abundant food supply; and diverse well-established riparian communities. In the Tillamook Bay estuary, plentiful salt marsh, tidal channel, and eelgrass habitats are needed to provide young salmonids with protection and food. Oceanic habitat also plays a role in salmonid survival. Since anadromous individuals reach sexual maturity and gain roughly 95 percent of their weight in the marine environment, a healthy marine food web is needed. We're All Part of the Problem No single factor is responsible for Tillamook's degraded salmonid habitats. Many productive human activities in the bay and watershed over time have altered, degraded, or converted the riparian, instream, wetland, estuary, and tidal habitats that salmonid species need. In fact, all human activities in the watershed potentially affect salmonid habitat! Timber cutting may remove shade and large logs that would have fallen into a stream. Poor logging, agricultural, and development practices can degrade riparian areas. Without riparian vegetation, erosion is likely to increase, carrying bacterial or chemical pollutants and excess sediment that clogs gravel needed for spawning. Reduced shade raises stream temperatures. The construction that typically accompanies human development—dikes, roads, culverts, and dams—can block fish passage and alter water flow. Dams can slow the force of the river's flow, preventing it from cleansing sediment from its gravel beds. Confining streams to straight channels and reclaiming wetlands may seem convenient for human purposes, but these actions are detrimental to salmon populations. Removing meanders and filling wetlands eliminates feeding and slow-water areas needed by young coho and other salmon for protection from predators or swift water currents. These practices can also increase the frequency and severity of major flood events, which are likely to restructure stream channels, damage riparian buffers, and export woody debris. Image and Data Credits What's Next? See what we're doing to improve habitat.