Pacific Northwest Coastal Rivers & Streams - A Global Ecoregion
Distinguished by large-scale migrations of anadromous fish
Snapshot: Ecoregion 176
Size:
290,000 sq. km (110,000 sq. miles)
Habitat type:
Small Rivers
Geographic Location:
North America: California, Oregon, and Washington
Conservation Status:
Critical/Endangered
Quiz Time!
Are Salmon well adapted to fast-flowing waters?
Answer:
Salmon are not the biggest fish in the world, but they may be among the most robust. In spring, young salmon swim for hundreds of miles downstream through rushing rapids, over waterfalls, through industrial and agricultural pollution, and (if lucky) past the spinning turbines of dams. After growing up at sea, many of these salmon find their way back to the exact place where they were hatched. And once they deposit eggs in rocky nests and fertilise them, the adults die.
Answer:
Salmon are not the biggest fish in the world, but they may be among the most robust. In spring, young salmon swim for hundreds of miles downstream through rushing rapids, over waterfalls, through industrial and agricultural pollution, and (if lucky) past the spinning turbines of dams. After growing up at sea, many of these salmon find their way back to the exact place where they were hatched. And once they deposit eggs in rocky nests and fertilise them, the adults die.
About the Area
The rivers and streams of northwestern United States, specifically the Sacramento/San Joaquin River basin in the Central Valley of California, the Klamath River basin, and coastal streams and rivers of Oregon, contain many endemic species.
These rivers support large numbers of migratory fish that ascend from the ocean to freshwater environments to spawn.Important not only as a spectacular natural phenomenon, this migration also helps the transfer of nutrients from marine to freshwater environments.
However, introduced species threaten native fish and invertebrates; of the present-day fish fauna in the region, nearly 40 per cent may be introduced species, most from eastern North America.
Local Species
The most prominent migrating species are salmon, including Pink (Oncorhynchus gorbuscha), Chum (O. keta), Chinook (O. tshawytscha), Coho (O. kisutch), and Sockeye (O. nerka). Other migrating fish include multiple species of trout, lamprey, sturgeon, sculpin, and stickleback.
Some of the endemic fish species are Pit-Klamath brook lamprey (Lampetra lethophaga), Western brook lamprey (L. richardsoni), White sturgeon (Acipenser transmontanus), Sacramento blackfish (Orthodon microlepidontus), Klamath smallscale sucker (Catostomus rimiculus), and Sacramento squawfish (Ptychocheilus grandis). Endemic invertebrates include Shasta crayfish (Pacifastacus fortis) and endemic syncarid shrimp species (Syncaris spp.).
Threats
Logging, introduced species, water diversion, and impoundments have resulted in serious problems like siltation, increased water temperatures, altered flow regimes, and disruption of fish migration routes. In addition, there is growing concern that warming ocean temperatures may adversely affect migrating salmonids during the oceanic portion of their life cycle.
Anadromous fish (those that migrate from freshwater to the ocean and back to freshwater) have suffered great losses in the face of huge changes to their habitats over the last 100 years. For example, coho salmon in California are at less than 5 percent of their historic numbers.
Resources
• NationalGeographic.com
