Lake associations and property owners can be a major influence in curbing the spread of zebra and quagga mussels. Utilizing best management practices and identifying invasive mussel populations in their early stages may prevent lakes from becoming fully infested. If you believe you have identified zebra or quagga mussels in your waters, check with your state’s or province’s aquatic invasive species program to ensure proper reporting. Avoid taking samples or removing any mussels from the water until you have contacted your state’s or province’s aquatic invasive species program and received guidance or instruction; possession and/or transport of zebra and quagga mussels is prohibited in many jurisdictions.
Identifying Invasive Mussels
The most obvious identifying feature of zebra and quagga mussels are their byssal threads. Zebra and quagga mussels are the only freshwater mussels that are able to anchor themselves to hard substrates, such as docks and watercraft. Byssal threads allow invasive mussels to adhere themselves to firm surfaces and avoid being swept away by water movement.
Other identifying features:
- Shells are “D” shaped, and typically have dark and light stripes.
- Zebra and quagga mussels are generally small, and may be up to 2 inches in length. However, most zebra mussels are less than 1 inch long.
- Mussels tend to grow in clusters, which may be easier to spot than individual mussels.
- Zebra mussels are triangular, while quagga mussels have a more oval shape.
Developing a prevention plan for your body of water can be a helpful tool in preventing the introduction or establishment of zebra and quagga mussels. Consider how you may determine the potential for introduction of invasive species, and contact your jurisdiction’s aquatic invasive species program for information about how to monitor for invasive species. See the California Department of Fish and Wildlife’s Guidance for Developing a Dreissenid Mussel Prevention Program for more specific guidance on developing a prevention plan. Remember to always consult your local and state/provincial agencies before undertaking any activities related to invasive mussels. Different jurisdictions may have specific recommendations and guidance for specific types of activities, and local, state, provincial, and federal authority must be followed at all times. Some important points for consideration within a prevention plan include:
- Who uses my body of water? How many people typically visit my body of water per week? How knowledgeable may these people be about invasive mussels?
- During which month(s)/season(s) is my water body open for use? How many days per week is my water body open for use? How many hours per day is my body of water open for use?
- How do people typically use my water body for recreational purposes? What types of vessels are allowed in the water? Are motorized watercraft launched into my water body? Are watercraft other than boats (e.g. jet skis) used in my body of water? What types of gear are used in the water (e.g. for fishing)? Are any watercraft or gear left in the water overnight, or for an extended period of time during the season?
- Are there any programs (e.g. boat launch inspections) currently in place to prevent the introduction of invasive species into my water body?
- Who should I contact in my state or province if I think zebra mussels or other invasive species are present in my water body?
For more information about developing prevention programs for private reservoirs, see the California Department of Fish and Wildlife’s page for Dreissenid Mussel Prevention Program Development.