Eurasian Ruffe - An Aquatic Invasive Species Threatening The Great Lakes Kristin Mantzoris

Classification Chart for the Eurasian Ruffe

Physical / Structural and Behavioural Characteristics

Physical Characteristics: The Eurasian Ruffe is a relatively small fish reaching up tp 10 inches in length, is olive-brown to golden-brown on its back with yellowish white undersides. It is typically slimy when handled. A ruffe produces an abundance of eggs and reaches maturity very quickly.

Structural Characteristics: A few characteristics of the Eurasian Ruffe include, rows of dark spots between spines, a sharp spiny fin, a soft fin, two very sharp spines, one sharp spine, a gill cover with many sharp spines, a small down-turned mouth and glassy eyes.

Diagram depicting structural characteristics of a Eurasion ruffe

Behavioural Characteristics: Eurasian Ruffe are capable of adapting to a wide range of environmental conditions and habitats, including fresh or brackish water with low or high nutrients, and a wide range of depths and temperatures. Ruffe feed from the bottom of the food chain, and will compete with native and introduced species dependent on the same fauna.

Natural Habitat(s) and Ecosystems it Invades

The ruffe appear to be closely associated with the bottom. They are found in the deepest channels (8 to 10 meters deep) at ice-out, move into the shallows to spawn, mainly remain in water 1 to 3 meters deep throughout the summer and return to the deeper channels in September and October.

( Map of where the Eurasian Ruffe is found )

How Eurasian Ruffe Migrate

The Eurasian Ruffe is originally from northern Europe and Asia. It was introduced to Canada and the United States unintentionally through the ballast waters of a ship crossing the ocean. It now invades the Great Lakes such as lake Superior, Huron, and Michigan.

Picture of ballast waters of a ship

Invasive Impacts

Unfortunately, there aren’t positive invasive impacts attributed to the Eurasian Ruffe. Ruffe consume a variety of different food and have very few predators because the sharp spines on their fins make it difficult for other organisms to eat it. They mature quickly (2-3 years) and have an average lifespan of 7 years. This species has the potential to affect ecosystems in the following ways:

• They can seriously damage native sportfish populations, such as, yellow perch by directly competing for food, habitat or through heavy predation of native sportfish eggs.

• Ruffe can very quickly become the most dominant fish in local areas because of their rapid reproductive and growth rates. This puts pressure on native species and contributes to their decline.

• Given time, they have the potential to spread to all of the Great Lakes and many inland waters as well.

Efforts to Control the Eurasian Ruffe

There are many different ways to control the Eurasian Ruffe. A few ways to control it are:

  • Do not use it as bait when you are fishing.
  • Clean all aquatic plants, animals and mud from watercraft, trailers, docks, lifts, anchors and other recreational equipment before leaving access. Dry for at least 5 days.
  • Drain water-related equipment (boat, ballast tanks, portable bait containers, motor) and drain bilge, livewell and baitwell by removing drain plugs before leaving water access. Keep drain plugs out while transporting watercraft.
  • Dispose of unwanted bait, worms and fish parts in the trash.
  • Do not release fish from one body of water into another.
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Kristin Mantzoris

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