Aquatic invasive species pose an ongoing threat to Washington's environment and economy. Anyone who uses Washington's waters – for work or play – can help stop the spread of these non-native species.
Invasive species, such as zebra and quagga mussels, European green crab and New Zealand mudsnails, are often spread by boats, trailers and other means of transportation. Once non-native species become established in a new environment, where their natural enemies are missing, these invaders can spread rapidly.
Invasive species can damage irrigation and water systems, clog hydroelectric dam intakes, disrupt efforts to recover endangered salmon stocks, and out-compete native and commercially grown species. Non-native species also affect recreation, potentially reducing fish populations for anglers and forcing the closure of waterbodies for boaters and others who enjoy Washington's waters.
Both marine and freshwater can harbor invasive species. One of the most well-known invasive species are zebra and quagga mussels. Zebra and quagga mussels have caused billions of dollars in economic and ecological damage to the Great Lakes, and have spread throughout North America. Quagga mussels are present in Lake Mead (Nev. and Ariz.) and Lake Havasu, Calif., which greatly increases the risk of introduction into Washington state.
Readily observed examples of aquatic invasive species in the inland marine waters of Puget Sound include tunicates, oyster drills, varnish or dark mahogany clams, and cordgrasses.
Freshwater invasive species in Washington include New Zealand mudsnails, Asian clams, Red Swamp crayfish, and Eurasian water milfoil.
Preventing the introduction and spread of aquatic invasive species in Washington is challenging and unpredictable. Discovery and continued findings of potentially invasive species on Japanese tsunami marine debris is a good example of a new threat to the state's coastal waters. The Washington Department of Fish and Wildlife (WDFW) asks anyone who visits state waters to take simple steps to prevent the spread of aquatic invasive species. Penalties for transporting aquatic invasive species in Washington include up to one year in jail and a maximum fine of $5,000.
Questions or comments regarding the state’s Ballast Water Management Program may be directed to: