Lake Washington, a freshwater body spanning approximately 22,000 acres between Seattle and Bellevue, is a significant natural resource in the Pacific Northwest. Its ecosystem supports a diverse array of aquatic life.
Native Fish Species
Lake Washington is home to various native fish species. Several salmonid species are found here, including Coastal Cutthroat Trout, which maintain a healthy, naturally sustaining population. These trout typically measure between 7 and 9 inches, though some grow larger, and are identifiable by red slashes under their jaws and small teeth on their tongues. Chinook Salmon, a threatened species, are also present, with two distinct populations associated with the Cedar River and Sammamish River systems. Juvenile Chinook utilize shallow-water habitats within the lake before migrating to Puget Sound.
Sockeye Salmon, particularly the landlocked form known as Kokanee, were once abundant in Lake Washington, but their populations have declined, with most now found in Lake Sammamish. Coho Salmon are another salmonid, with schools often concentrating in the northern parts of the lake. Other native salmonids include Steelhead Trout and Rainbow Trout, which are the same species, with rainbow trout remaining in freshwater. The lake also supports native char species like Bull Trout and Dolly Varden Trout; Bull Trout are considered threatened. Beyond salmonids, Lake Washington hosts other native fish such as Peamouths, known to spawn in areas like Andrews Bay and Kelsey Creek. Primitive, jawless fish like the Pacific Lamprey, River Lamprey, and Western Brook Lamprey are native to the watershed and face threats to their existence.
Non-Native Fish Species
Lake Washington’s fish community includes several non-native species. Smallmouth Bass were introduced in 1925 for sport fishing. These fish prefer rocky or gravel substrates, aquatic vegetation, and artificial structures like docks, with abundance peaking in littoral zones during warmer months. Largemouth Bass are also present, though less common than Smallmouth Bass, often found in lily pads over muddy bottoms, particularly in the lake’s northern end. Both bass species prey on juvenile salmon, posing a management challenge.
Yellow Perch are an abundant non-native species, known for their prolific populations in Lake Washington, to the extent that there is currently no catch limit. These fish typically range from 4 to 10 inches and school around weedy areas, rocky shallows, and docks. Brown Bullhead, a type of catfish, prefer muddy bottoms and tolerate low oxygen conditions. They are opportunistic bottom feeders, characterized by eight barbels around the mouth and lack of scales. Other introduced species include Common Carp and Black Crappie, found around underwater structures. Northern Pike, an invasive and aggressive predator, have been illegally introduced, prompting active removal efforts by the Washington Department of Fish and Wildlife due to their potential to consume native fish, including salmon and trout.
Conservation and Management Efforts
Managing Lake Washington’s fish populations is important for its ecological health and biodiversity. Various agencies, including the Washington Department of Fish and Wildlife (WDFW), the US Fish and Wildlife Service, and local tribal entities such as the Muckleshoot Indian Tribe, collaborate on these efforts. A significant focus is on habitat restoration, involving increasing overhanging vegetation, reducing bank hardening, and restoring shallow-water habitats, particularly beneficial for juvenile Chinook Salmon. Examples of such restoration sites include Seward Park and Chinook Beach.
Monitoring programs track fish populations, with methods like night snorkeling used to count salmon. Management also addresses non-native species, especially those that prey on young salmon. The WDFW actively removes Northern Pike, bass, and other non-native predatory fish. Recommendations exist to reclassify some non-native predatory fish, like bass and walleye, as invasive to facilitate their removal by eliminating catch limits. Efforts also improve fish passage by removing barriers such as culverts and address stormwater runoff to enhance water quality. These initiatives are supported through various funding sources and partnerships, aiming to maintain a balanced and healthy aquatic ecosystem.