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Stop Aquatic Hitchhikers!

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The quality of our waters is extremely valuable, both as a natural and economic resource. In addition to providing essential aquatic habitat, New Hampshire’s waters annually provide 14.7 million visitor days for boating, fishing and swimming —popular family-oriented recreational activities that generate more than $1 billion to the state’s economy each year. Your help is needed to protect these resources. It’s up to boaters and anglers to keep nuisance species from invading N.H.’s waters!

New Hampshire’s waters are threatened by several non-native aquatic invasive plants and animals. They can easily be transported to new waters by boats, motors, trailers, fishing equipment, live-wells, bait buckets, diving gear and other aquatic recreational equipment. Check your boat and equipment and remove any plants or other materials—milfoil and other invasives can easily adhere to propellers and many other catch points.

Invasives can also be put into our waters by individuals who are not aware of the environmental and economic damages these nuisance plants and animals can cause. Never release plants, fish or animals into a body of water unless they came out of that body of water. It’s the law!

Invasive Plants

It is illegal to transport, import, purchase, propagate, sell or distribute 14 species of non-native aquatic plants in N.H. Among the 14 species, variable milfoil is the most abundant and problematic invasive aquatic plant in N.H.

An invasive algae threatening our waters is “didymo” or “rock snot,” which is present in the Connecticut River and several tributaries. If you fish, boat or swim in this river, disinfect all of your gear before using elsewhere.

Invasive Animals

Nonnative invasive animals are also a growing concern in New Hampshire. Zebra mussels and quagga mussels can attach to boat hulls and clog water intake systems. They are not here yet—it is extremely important to keep them out of New Hampshire waters.

Asian clams are already present in the lower Merrimack River and several ponds; they compete with native mussels for space and food.

The Chinese mystery snail is also here, present in lakes and ponds in southeastern New Hampshire. Rusty crayfish have been found in Vermont. The spiny water flea is present in the Great Lakes. These invaders compete with native species for zooplankton, impacting the entire food chain.

Learn More

For more information, contact the N.H. Department of Environmental Services Exotic Species Program at 603-271-2248,; N.H. Fish and Game at 603-271-2501,; or visit

Regulations in red are new this year.

Purple text indicates an important note.

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