Fish Invaders

Lake Champlain’s Invasive Fish Species

 

Let’s begin with a look at some of the invasive fish species that are threatening Lake Champlain and its native ecosystem. .

 

Round goby: (Neogobius melanostomus) Native to the Caspian and Black Sea regions, Gobies were probably introduced to the Great Lakes from a ship’s discharged ballast water in the 1980’s. They are bottom-dwellers perching on rocks and substrate. They grow up to ten inches long and have large heads, soft bodies and dorsal fins lacking spines. Often confused with sculpins, the round goby is distinguished by its fused pelvic (bottom) fin which forms a suction disk that allows them to anchor to the bottom. No native North American fish has this feature.

Round gobies are predators of many native fish such as darters, sculpins, and logperch; this has led to serious declines in populations of some of these native species in other areas. Gobies also eat eggs and fry of lake trout, and eggs of lake sturgeon. They have been implicated in major bird die-offs in the Great Lakes because they can harbor the bacterium that causes avian botulism; this bacteria is then transmitted to the birds that have eaten the Gobies.

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The Eurasian Ruffe: (Gymnocephalus cernuus) is a nonnative nuisance fish threatening the ecosystem and sport fish population of Lake Champlain. First found in Lake Superior in 1986, the ruffe has since expanded its population and range considerably. It is a perch-like fish native to Eurasia that usually grows no bigger than six inches.

Ruffe impact native species and sport fish populations by eating their eggs and competing for food and habitat.  Since they mature quickly, they are highly competitive, have high reproductive potential, and are adaptable to a wide variety of habitats.

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Alewife (Alosa pseudoharengus) were confirmed in Lake Champlain in 2003. In 2008, widespread alewife die-offs occurred in the Lake, confirming that large numbers are now present. Although alewives do undergo periodic mass mortality events, the specific cause of the Lake Champlain die-off is unclear.

The alewife is a marine fish species from the herring family. Native populations of this fish inhabit the Atlantic Ocean. Each spring, adult alewives migrate into freshwater rivers to spawn. The young hatch in the rivers, reside there for the summer, and then migrate out to sea in early fall where they mature as adults. Alewives can, however, survive in freshwater. Alewife populations have become established in Great Lakes and many landlocked lakes in New York, Maine, Connecticut, and other New England states.

Alewife threaten the native species of Lake Champlain by altering zooplankton communities, competing with other fish for food, and feeding on native fish eggs and larvae. They also pose a threat to Lake Trout and Atlantic salmon who can experience reproductive failure when feeding on an alewife diet due to a severe vitamin B deficiency. Biologists are concerned that the establishment of this exotic fish species in the Lake and other Basin waters could prove to be a major threat to native forage and game fish populations.

 

Tench: (Tinca tinca), originally from Germany, was first caught and identified on the Great Chazy in New York in May 2002. Similar to carp, tench live on lake or river bottoms. They are a slimy, slow moving carnivorous member of the minnow family that prefer shallow water and weedy areas where they feed on invertebrates. It is not known how the tench found its way to the Great Chazy, although the Richelieu River already has a viable tench population.

The tench has a tendency to cloud the water where it lives by stirring up the bottom sediments. These fine sediments can suffocate the eggs and newly hatched fish of native species such as pike, perch or crappie.

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White Perch: (Morone americana)  are a relatively new non-native invasive species of increasing concern in the Lake. In 2003, Quebec researchers found that white perch far outnumber native perch in Missisquoi Bay and are now that Bay’s most abundant fish. They may displace native perch by feeding on their larvae and compete for zooplankton which can lead to an increase in algal growth. White perch are also known to prey on walleye eggs along with white crappy, which has contributed to the significant decline in the walleye population.

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Next we’ll look at some of the invasive invertebrates trying to ‘mussel’ and claw their way into Lake Champlain.

Next: Invasive Invertebrate Threats to Lake Champlain ( Next >> )

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