Invasive mussel interception demonstrates crucial need for prevention
WDFW removed a record-setting 21 gallons of invasive mussels from a single vessel intercepted by staff at the Spokane watercraft inspection station in early January. Samples that WDFW staff collected during removal confirmed the vessel was infested with zebra mussels, though photos may also indicate the presence of quagga mussels. Critically, analysis revealed that some of the intercepted mussels may have still been alive — highlighting how crucial it is to stop invasive mussels at the state’s borders.
Unlike native mussels, quagga and zebra mussels have thread-like ropes called byssal threads that allow them to attach to surfaces like rocks, water intake pipes, watercraft, and even native mussels. They can survive out of the water for 30 days depending on environmental moisture and temperature and up to 7 days in freezing temperatures, allowing them to hitch a ride on mobile aquatic equipment for long distances.
If infested equipment moves to a new waterbody, attached invasive mussels can start to reproduce with a single mussel producing over 1 million eggs per year. Quagga and zebra mussel larvae are microscopic and free-floating, using water currents to carry them to new areas to infest. As they age, they gain the ability to swim and settle as juveniles wherever their byssal threads can attach.
Free from predators existing in their native Caspian Sea, quagga and zebra mussels quickly take over critical habitats for native species like steelhead and salmon, threatening billions in investments in salmon recovery in the Columbia River Basin, freshwater ecosystems, and fish and wildlife resources. Habitat destruction and impacts to native species have broader implications statewide. Decreasing salmon populations due to habitat loss means less food for the endangered Southern Resident killer whale population, which relies on Chinook salmon.
Decreasing populations of fish also impact recreation with more than a quarter of outdoor recreation taking place on Washington’s public waters generating $5 billion annually. Recreational fishing activities alone generate more than $1.5 billion in economic activity annually in Washington state. Domestic commercial fisheries create nearly 23,000 jobs in Washington and salmon harvest is worth nearly $14 million annually.
Economic impacts aren’t limited to fisheries. Due to their unique ability to attach to solid surfaces using their byssal threads, quagga and zebra mussels can damage critical infrastructure including water intake pipes, utilities, locks, and dams putting billions of dollars in industry and trade at risk. Management and mitigation costs are expected to exceed $100 million each year.
Three-quarters of Washington’s agriculture is irrigated, relying on a variety of water sources. While groundwater withdrawals supply irrigation water to many areas, a majority of water used for irrigated agriculture is diverted from streams and rivers, relying on water intake pipes and infrastructure at risk of becoming clogged by quagga and zebra mussels. An industry worth $9.6 billion to our economy, disruptions to irrigated agriculture will increase food production costs, resulting in higher prices and greater food insecurity statewide.
Clogged water intake pipes will also have an impact on the cost and availability of drinking water and increased water pollution caused habitat destruction requires additional efforts to clean.
In 2022, the Columbia Snake River System, a key U.S. trade gateway, handled $31.2 billion in national and global trade. As the leading wheat export gateway, second for soy and corn, additional costs for managing and mitigating the impacts of quagga and zebra mussels along trade routes may also contribute to higher food prices and food insecurity.
If unchecked, invasive mussels will lead to catastrophic consequences for Washington’s environment, economy, and human health — to our way of life. While WDFW works to intercept invasive mussels at the state’s borders, it’s crucial that anyone who works or recreates on the water remember to clean, drain, and dry all your gear and equipment after every use — especially if you’re headed to another waterbody. It’s illegal to transport aquatic invasive species from one waterbody to another and can cost you up to $5,000 or a year in jail. Keeping our waters safe from invasive mussel infestation depends on all of us.
Learn more about aquatic invasive species prevention and threats by visiting the WDFW’s AIS webpage.
