Aquatic Invasive Species Update

Mike Hoff, an AIS coordinator with the US Fish and Wildlife Service gave a preview on the highly impactful AIS plants and animals that we could likely see in Minnesota and by extension, Lake Minnewashta. These species include:

Spiny waterfleas – this invasive animal is very small, but does significant damage to the zooplankton in the water. In fact, the spiny waterfleas do more damage to the lowest level of the fish food chain than zebra mussels. This species is already in Minnesota and is in Lake Mille Lacs, Lake Superior, and many rivers and lakes in the northern Minnesota counties of Cook and St. Louis

Hydrilla – This plant is commonly referred to as “milfoil on steroids”. It is coming up from the southern US and is already as far north as Indiana. Hydrilla grows aggressively and competitively, spreading through shallower areas and forming thick mats in surface waters that block sunlight penetration to native plants below. Its heavy growth may obstruct boating, swimming and fishing in lakes.

Quagga mussels – The larger cousin of the zebra mussel does more damage to the zooplankton than the zebra mussel. It is widely found in the easternmost Great Lakes and and is having a significant impact on Lake Mead, Lake Powell and the Colorado River in the western US. As of now it is only found locally in the Duluth-Superior harbor area of Lake Superior.

Viral hemorrhagic septicemia (VHS) – This virus affects fish and is currently established in Lake Superior. The virus may have limited affect on some fish, but others may become hyperactive and display nervous symptoms. In its most severe form, fish become lethargic and dark, with bulging eyes as well as liver and kidney abnormalities. They also have bleeding in their eyes, skin, gills, fin bases, skeletal muscles, and internal organs. This form of the disease almost always kills the infected fish.

Starry stonewort – A fast growing algae, found in Minnesota only in Lake Koronis (near Paynesville), but prevalent in New York, Indiana, and Michigan. It forms dense mats from the lake bottom to the surface reaching heights of 10-12 feet. The dense mats directly impact the habitat used by native fish for spawning. It is difficult to mechanically remove from an inland lake because of the large amounts of biomass. Additionally, it is typically the first to reestablish in the disturbed area because it is such an aggressive and efficient recolonized.

Supporting and using the pre-launch inspection at all accesses to the lake is important to prevent any of these invasives from entering our lake.

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