Location and Impact of the European Ruffe



     http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=7

http://en.wikipedia.org/wiki/Ruffe

     The Eurasian Ruffe is a freshwater fish native to the temperate regions in Europe and Northern Asia.  It has been introduced into the Great Lakes region of the United States with many unfortunate results.  The ruffe was first collected in 1986 from the St. Louis River at the border of Minnesota and Wisconsin. It subsequently spread into Duluth Harbor in Lake Superior and several tributaries of the lake.  It is found in the Amnicon, Flag, Iron, Middle, Raspberry, and Bad Rivers, Chequamegon Bay, and Apostle Islands National Lakeshore in Wisconsin.   It was found in Saxon Harbor, Wisconsin, and in the upper peninsula of Michigan at the mouths of the Black and Ontonagon rivers.  In the lower Peninsula of Michigan along Lake Huron, the first three specimens were caught at the mouth of the Thunder Bay River in August 1995.  This species has also been collected in Michigan in Lake Michigan, Lake Superior, Torch Lake, Little Bay de Noc in Escanaba, Big Bay de Noc, Misery River, Ontonagon River, Thunder Bay, and Sturgeon River Sloughs.  The ruffe has been collected in Lake Superior at Thunder Bay Harbour, Ontario, Canada.  The ruffe was probably introduced via ship ballast water discharged from a vessel arriving from a Eurasian port, possibly as early as 1982-1983.  Recent genetic research has indicated that the origin of ruffe introduced to the Great Lakes was southern Europe, not the Baltic Sea as previously believed. 

Impact:
      -The ruffe has affected fish populations in other areas where introduced. In Scotland, native perch populations declined, and in Russia whitefish numbers have declined because of egg predation by ruffe.

      -Ruffe exhibit rapid growth and high reproductive output, and adapt to a wide range of habitat types therefore the species may pose a threat to native North American fish.
      -Yellow perch, emerald shiners, and trout-perch have all declined since the introduction of the ruffe.
      -There is much concern that ruffe may have a detrimental effect on more desirable species in Lake Superior, such as yellow perch and walleye, by feeding on the young of these species or by competing.
      -Findings indicated that the species prey heavily on benthic insects thereby suggesting that ruffe compete for food with yellow perch, trout-perch, and other native benthic-feeding fishes.
      -Ruffe hold an advantage over native perch in their ability to better select moving objects under relatively dim light conditions or at high turbidity.
      -Ruffe have a very sensitive lateral line system and night adapted vision, and are more adapted to foraging under poor light conditions that yellow perch.
      -In a study of ruffe predation by native pike, bass, bullhead, walleye, and perch found that though ruffe comprised 71-88% of prey species biomass, all five of the selected predators ate ruffe at lower proportions, preferentially selecting native fish species.

       

The Origin and Distribution of Rusty Crayfish



http://www.seagrant.umn.edu/ais/rustycrayfish_invader

     Rusty crayfish were not found in Wisconsin in a 1932 survey, but populations have rapidly expanded throughout Wisconsin lakes and streams since their introduction around 1960.  Rusty crayfish have been observed in 430 Wisconsin lakes and streams and the occurrence of rusty crayfish in sites that support crayfish has increased from 3% in the 1970s to approximately 50% in 2007.

     The first observation of rusty crayfish in Minnesota was in 1967 at Otter Creek in southern Minnesota. Since then, their range has expanded to approximately 50 different lakes and streams spanning 13 counties.  Rusty crayfish from east central Minnesota  may have resulted from the natural dispersal of introduced populations from Wisconsin. People most likely spread rusty crayfish to the other waters of Minnesota where they are currently found.

     Presumably people can spread crayfish in several ways. Anglers using crayfish as bait are thought to be the primary means of spread. While crayfish never were a significant component of Minnesota live bait sales, they are popular in other states and may have been brought to Minnesota by non-resident anglers.  Rusty crayfish are also sold to schools by biological supply houses. Even though a warning not to release rusty crayfish into the wild accompanies these crayfish, such warnings may be forgotten, or live crayfish may be given away to students. Crayfish from schools or collected from the wild and placed in home aquariums may eventually be released.  Developing a viable commercial harvest of rusty crayfish from natural lakes could be incentive for unscrupulous trappers to plant them into other waters. In fact, this may have contributed to the spread of rusty crayfish in Wisconsin.  The harvest of rusty crayfish for food and bait may provide the only beneficial use for this exotic. Harvest for bait has been going on for over 40 years in Wisconsin. Commercial harvest for food is more recent and varies from year to year in Wisconsin and Minnesota. Regulations in both states make it illegal to introduce rusty crayfish into any waters. In Minnesota, it is illegal to sell live crayfish as bait or as aquarium pets.

    

Locations and Impacts of 4 Invasive Carp Species

Grass Carp



http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=514

Grass carp populations have been recorded in 45 states including the Great Lakes region of the United States (Lake Huron and Lake Ontario).  The only states that these carp haven't been introduced to are Alaska, Maine, Montana, Rhode Island, and Vermont.  

     -Negative effects involving grass carp included interspecific competition for food with invertebrates (e.g., crayfish) and other fishes, significant changes in the composition of macrophyte, phytoplankton, and invertebrate communities, interference with the reproduction of other fishes, decreases in refugia for other fishes, and so on.

     -Grass carp seem to affect other animal species by modifying preferred habitat, an indirect effect.

     -Grass carp may directly influence other animals through either predation or competition when plant food is scarce.  Grass carp have significantly altered the food web and trophic structure of aquatic systems by inducing changes in plant, invertebrate, and fish communities.

     -Large populations of grass carp decreases the density and composition of aquatic plant communities.

     -Organisms requiring limnetic habitats and food webs based on phytoplankton tend to benefit from the presence of grass carp.

     -Declines have occurred in the diversity and density of organisms that require structured littoral habitats and food chains based on plant detritus, macrophytes, and attached algae.

     -Removal of vegetation can have negative effects on native fish, such as elimination of food sources, shelter, and spawning locations.

     -Although grass carp are often used to control selected aquatic weeds, these fish sometimes feed on preferred rather than on target plant species.

     - Increases in phytoplankton populations is a secondary effect of grass carp presence.

     -A single grass carp can digest only about half of the plant material that it consumes each day. The remaining material is expelled into the water, enriching it and promoting algal blooms.  These blooms can reduce water clarity and decrease oxygen levels in the water.

     -Grass carp may carry several parasites and diseases known to be transmissible or potentially transmissible to native fishes.

      Black Carp

http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=573

The black carp has been reported in Arkansas, Illinois, Mississippi, and Missouri.  There appears to be no existing, economically feasible method to completely eliminate black carp populations once they escape into large river systems. 

     -There is high potential that the black carp would negatively impact native aquatic communities by feeding on, and reducing, populations of native mussels and snails, many of which are considered endangered or threatened.

     -Given their size and diet preferences, black carp have the potential to restructure benthic communities by direct predation and removal of algae-grazing snails.

     -Based on the fact that black carp attain a large size (well over 3 feet long), both juvenile and adult mussels and snails of many species would be vulnerable to predation by this fish.

     -The effectiveness of black carp in significantly reducing snail populations in aquaculture ponds indicates that any black carp occurring in the wild may cause significant declines in certain native mollusk populations in North American streams and lakes.

Bighead Carp

http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=551

This species has been recorded from within, or along the borders of, at least 18 states. There is evidence of reproducing populations in the middle and lower Mississippi and Missouri rivers and the species is apparently firmly established in the states of Illinois and Missouri.

     -These carp have the potential to deplete zooplankton populations.  A decline in the availability of plankton can lead to reductions in populations of native species that rely on plankton for food, including all larval fishes, some adult fishes, and native mussels.  



Silver Carp

http://nas.er.usgs.gov/queries/speciesmap.aspx?SpeciesID=549

Populations of silver carp have been recorded in 12 states.

     -In numbers, the silver carp has the potential to cause enormous damage to native species because it feeds on plankton required by larval fish and native mussels.

     -This species would also be a potential competitor with adults of some native fishes, for instance, gizzard shad, that also rely on plankton for food.

     -Silver carp also have the potential to impact certain regions such as the Great Lakes region economically.