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Aquatic Nuisance Species

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Examples of Some Aquatic Nuisance Species in Vermont Waters

ALEWIFE: Invasive baitfish species first found in Lake St. Catherine in 1997 and Lake Champlain in 2004. May displace smelt and other native forage fish through competition for food and space resources. Trout and salmon that feed extensively on alewives may also suffer reproductive failure. Alewives may not be used as bait in Vermont except for on Lake Champlain, and only as dead bait. Please see the complete Vermont baitfish regulations on General Regulations & Prohibitions for complete details.

DIDYMO: An invasive freshwater microscopic algae documented in several rivers in the Lake Champlain basin, Connecticut River watershed and the Batten Kill. M ay form extensive ‘blooms’ on the bottoms of rocky river beds.

EURASIAN WATERMILFOIL: Prolific invasive aquatic plant found in Lake Champlain and many inland lakes in Vermont. May interfere with boating and swimming, and can displace native aquatic plant species. Easily spread when plant fragments are caught and moved on boat trailers, propellers, anchors, and other equipment.

MUTE SWAN: Very large white bird with orange bill, observed annually in Vermont since 1993. Highly aggressive during the nesting season and may drive away or kill native waterfowl. May also attack humans and negatively impact aquatic habitats.

SEA LAMPREY: Parasitic aquatic nuisance fish found in Lake Champlain and a number of its tributaries. Preys on salmon, trout, sturgeon and other fish, causing substantial economic impact to the lake’s fisheries. Anadromous sea lampreys in the Connecticut River watershed are not parasitic when they migrate upriver to spawn and are not a nuisance species.

SPINY WATER FLEA: Tiny invasive crustacean that first appeared in Lake Champlain in 2014. Alters native plankton populations, clogs fishing rod guides, fouls fishing line, and alters native plankton populations. Spread by hitchhiking on boating or fishing gear that isn’t cleaned, or in bilge water, bait buckets or livewells that aren’t drained before moving to a different waterbody.

VARIABLE-LEAVED WATERMILFOIL: Invasive aquatic plant recently discovered in Halls Lake, Newbury, VT as well as South Bay and Missisquoi Bay, Lake Champlain. Easily spread by fragments with impacts similar to the closely related Eurasian watermilfoil, but may be even more aggressive and difficult to control.

WATER CHESTNUT: Prolific invasive annual plant found in southern Lake Champlain and a few inland lakes. Interferes with boating, hunting and fishing, and displaces native aquatic plant species. Spreads by seeds or parts of plants caught on boats and equipment.

ZEBRA MUSSEL: Tiny D-shaped invasive mollusks, well established in Lake Champlain and Lake Bomoseen. Clogs water intake pipes, damages boat engines, obscures historic shipwrecks, and may alter native plankton populations. Adult zebra mussels can attach to and be moved on boat hulls, engines and other equipment. Microscopic larva can get trapped and moved in water of boat engines, bilges, bait buckets, and live wells.


Transporting any aquatic plant or aquatic plant part, zebra mussel or quagga mussel on the outside of a vehicle, boat, personal watercraft, trailer or other equipment is illegal. Violators are subject to a penalty of up to $1000. The use of felt-soled boots or waders in Vermont waters is prohibited. Violators are subject to a penalty of up to $1000. Visit for more information.

Regulations in red are new this year.

Purple text indicates an important note.

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