“Least wanted” AIS list

he Great Lakes and St. Lawrence Governors and Premiers have identified the “least wanted” aquatic invasive species (AIS) that present an Timminent threat to the Great Lakes-St. Lawrence River region. In 2013, the Governors and Premiers committed to take priority action on the transfer of these species to and within the region. Since then, the states and provinces have taken more than 50 separate actions to restrict these high-risk AIS, and the US federal government has similarly restricted four of the species. The list includes:

Bighead carp Silver carp Grass carp Black Carp Hypophthalmichthys nobilis Hypophthalmichthys molitrix Ctenopharyngodon idella Mylopharyngodon piceus Bighead carp feed on plankton, Similar to bighead carp in their Grass carp eat aquatic Black carp consume up to 20% a primary food for many native feeding habits, silver carp pose vegetation and degrade aquatic of their body weight per day fish including walleye, yellow additional threats to boating and habitats. They contribute to eating mussels and snails. If they perch, lake whitefish and all tourism throughout the Great Lakes. algal blooms, damage wetland become established in the Great juvenile fish. They pose a risk to The fish also are prone to leap out of ecosystems, and jeopardize Lakes, black carp could pose a the $7 billion fishing industry in the water, posing a threat to boaters waterfowl habitat. major threat to native mussels the Great Lakes. and the region’s $16 billion dollar and snails, and compete with boating industry. native fish.

Northern snakehead Stone moroko Zander Wels catfish Channa argus Pseudorasbora parva Sander lucioperca Silurus glanis Northern snakehead may Stone moroko, one of Europe’s Zander can force native Wels catfish is a very large, compete with and consume most invasive species, compete fish, including perch, out of voracious predator and a serious native fish species. They can with fish species for food, its preferred habitat. Direct threat to the populations of survive in waters with low oxygen consume native juvenile fishes, competition with native walleye, native fish and other vertebrates. levels, giving them a competitive act as a vector for infectious one of the prized species in the They can transmit parasites and advantage over native species. fish diseases, and contribute to Great Lakes, would be likely. The pathogens, and can negatively eutrophic conditions. high climate match of this species impact water quality. in the Great Lakes indicates the potential risk of invasion.

Tench Tinca tinca Tench have been documented in 38 states. They can survive in low oxygen, degraded waters, but it is unclear whether they cause these conditions or are simply filling a niche that native species cannot. Killer shrimp Yabby (crayfish) Golden mussel Marmorkreb (marbled Dikerogammarus villosus Cherax destructor Limnoperna fortunei crayfish) Killer shrimp is capable of Yabby has a rapid growth Golden mussel has the potential Procambarus fallax forma consuming a variety of prey rate, high spawning frequency, to affect the diversity of native virginalis and outcompeting other extended breeding period with mollusk communities and disrupt Marmorkreb are reported species. Shortly after invading multiple spawning events. They food webs through prolific to tolerate a broad range of a new area, it can eliminate a reach maturity at age one, colonization and extremely environmental conditions. As an wide range of species from the which helps facilitate rapid high filter feeding rates. Dead omnivore, it can use a diverse ecosystem. Killer shrimp have the establishment in and destruction mussels clog small water pipes at range of food sources, and potential to be transported to the of a new habitat. industrial facilities. native predators are unlikely to Great Lakes via untreated ballast be able to control their rapidly- water discharges. reproducing populations.

New Zealand mud snail Hydrilla Brazilian elodea Water soldier Potamopyrgus antipodarum Hydrilla verticillata Egeria densa Stratiotes aloides The New Zealand mud snail Hydrilla is perhaps the worst Populations of Brazilian elodea Water soldier crowds out native can reproduce rapidly and aquatic weed in the United dominate the environment by vegetation resulting in decreased create massive colonies. It may States. Plants form large, dense vigorous growth. The spread plant biodiversity. Dense floating outcompete or displace native populations which displace of this plant is most likely the mats hinder boating, angling snails, mussels, and aquatic native species, restrict flow, and result of human activity since it and swimming, and sharp insects which native fish species impair small boat navigation and is perhaps the most universally serrated leaf edges can cut depend on for food. other recreational uses. Hydrilla available aquarium plant. swimmers. can be transported to new waters by recreational boats and is already present in the Midwest.

European water Parrot feather Yellow floating heart European frogbit chestnut Myriophyllum aquaticum Nymphoides peltata Hydrocharis morsus-ranae Trapa natans Parrot feather is dense and Yellow floating heart can create Mats of European frogbit can Water chestnut forms dense can completely colonize small dense mats that shade out grow so thick that they impede floating mats that severely limit ponds and impede water flow in native aquatic plants, decrease boat traffic and movement of light, reduce oxygen levels, and drainage ditches and irrigation oxygen levels, increase mosquito large fish and diving ducks. compete with native species. canals. It may also outcompete breeding habitat, and impede Large mats prevent nutrients and Water chestnut also limits and replace native species that boating activity, fishing, and light from reaching submerged recreational activities and, if are more important to fish and swimming. vegetation. stepped on, can cause painful wildlife. Parrot feather poses a wounds. threat through water garden or aquarium trade, and may be dumped into local waters.