Variable Milfoil Discovered in Naticook Lake

The New Hampshire Department of Environmental Services and New Hampshire Fish and Game are asking people to check their watercraft for "aquatic hitchhikers," in an effort to reduce the spread of milfoil and other invasive species around the state.

Last week, Naticook Lake was one of two water bodies in the state to be discovered to play host to a strain of variable milfoil, an exotic aquatic plant. Both infestations were well-established when found and appear to have been present for at least two to three years before being reported.  The other infestation was newly documented at Otter Lake in Greenfield.

"Freshwater exotic aquatic plants are those that are not naturally found in New Hampshire’s lakes, ponds and rivers, and because they are not naturally found here, they have no predators or diseases that keep them in check, allowing them to grow quickly," according to a press release from the DES. "These exotic plants dominate the shallows of freshwater systems, to the detriment of native plants, fish, aquatic insects and other aquatic life. Exotic aquatic plants lead to water quality impairments, can reduce shorefront property values, and can be problematic to the aesthetic and recreational values of waterbodies."

DES said the two new additions bump the list of infested waterbodies in the state to 78 – 67 lakes and ponds and 11 river systems in the state.

Most contain a variable milfoil as the primary invasive plant. Other invasive plants known to local experts in New Hampshire's water bodies include water chestnut and Didymo (also known as rock snot, an invasive algae), among other common species.

According to DES, the milfoil found in Merrimack and Greenfield was found in waterbodies that don't have any sort of programs for prevention and early detection, allowing them to go unnoticed until they covered large areas. Infestations of the magnitude of those found in Naticook Lake and Otter Lake  are more difficult to manage, and eradication is not often feasible.

"The early ice out this year, along with warmer than average temperatures have contributed to more pronounced and rapid growth of exotic species," the DES press release says. "The DES urges lake and river residents and transient boaters to routinely monitor for exotic aquatic plants and report new infestations. Look for plants that appear to be dominating an area of a lake or river bed, that are brighter green in color, and that appear to be spreading quickly. Maps of existing infestations, as well as information, photographs and descriptions on exotic and prohibited plants in New Hampshire can be found on the Exotic Species Program page at www.des.nh.gov."

Two days after the announcement from DES of these discoveries New Hampshire Fish and Game sent out a press release with information about how to stop these aquatic hitchhikers from spreading. Invasive species love to travel from water body to water body attached to the likes of boats, motors, trailers, fishing equipment, bait buckets, diving gear and other recreational equipment.

"Even just a small piece of the plant, just 2-3 inches in length, is enough to cause a new infestation, so good old-fashioned visual inspection is an important precaution for boaters and anglers," says Scott Decker, Fisheries Program Supervisor at Fish and Game.

Some 500 "Lake Host" volunteers are stationed at 92 boat launches across New Hampshire lakes to provide a courtesy inspection and educate boaters on how to prevent the spread of exotic species, Fish and Game says. 

In 2011, a group of around 500 volunteers at 92 boat launches across the state, provided courtesy instpections of boats and equipment and recorded  68,158 courtesy boat and trailer inspections between mid-May and mid-October. Through that, 39 exotic species "saves" were managed at 17 waterbodies, 11 of which are currently free from exotic infestations. This year the program has already documented 36 saves. 

"There are not enough Lake Host volunteers to cover all our lakes and rivers, so we rely on boaters and anglers to be responsible and carefully check their own equipment," says Decker.

Follow these tips from Fish and Game to help prevent the spread of these invasive species:

• LOOK for "Warning Signs" for aquatic nuisance species near boat launch sites.
• HAND-REMOVE all materials (plant or animal) from equipment. Don't throw the material back into the water! Dispose of it far away from the water. Pay special attention to the bunks or rollers where the boat is seated on the trailer.
• WASH AND DRY all equipment before reuse. Hose off the boat, diving gear or trailer.
• DRAIN AND FLUSH the engine cooling system and live wells of your boat, your bait buckets and the buoyancy control device from diving equipment that's been in contact with an infested waterbody (to protect against the spread of zebra mussels).

For a list of exotic aquatic plants that are prohibited within New Hampshire, visit the N.H. Department of Environmental Services Exotic Species website. To find out more about the Weed Watcher Program and how you can get involved, visit the DES website.

For more information on what you can do to help prevent the spread of invasive aquatic plants and animals, visit http://www.ProtectYourWaters.net/nh. You’ll find the latest news about this problem, detailed procedures to prevent the transport of nuisance species, impacts caused by these species, facts about some of the more common "hitchhikers," and resources and ideas for you or your club to get involved with prevention efforts.

For more information or to report a potential new infestation, please contact the Exotic Species Program Coordinator at 603-271-2248.