Apostle Islands celebrates century of National Park Service
What's going on in your neighborhood this month? Meet other people and learn together at recreational and educational events! Our new dynamic calendar is updated daily with current educational events.
4 | More familiar species...and some foreign transplants
Lake Herring (Coregonus artedii)
Lake Whitefish (Coregonus clupeaformis)
Muskellunge, or muskie/musky (Esox masquinongy)
Northern Pike (Esox lucius)
Pumpkinseed (Lepomis gibbosus)
Related site: The bluegill sunfish: A cross dressing fish!
Rock Bass (Ambloplites rupestris)
Walleye (Stizostedion vitreum)
Yellow Perch (Perca flavescens)
Non-native and endangered speciesInvasive species and their impacts on the native fishery
Many commonly known Great Lakes fish, including chinook and coho salmon and rainbow trout, are actually non-native species that have been introduced to the lakes, either accidentally or intentionally.
When a species is introduced into a new habitat it lacks natural controls on its population; predators, and competitors are absent and prey don't know how to avoid them. Without these natural controls, populations of introduced species often explode. Examples of such introduced aquatic species in the Great Lakes include carp, zebra mussels, sea lamprey, goby and ruffe.
Perhaps one of the most notable accidental introductions was that of the sea lamprey (Petromyzon marinus) to the majority of the Great Lakes, between 1936 and 1946. This large, parasitic lamprey feeds on commercially important species such as whitefish and lake trout. Lamprey victims either die, or are no longer valuable because of the ugly scars left behind by the lamprey's "suction-like" mouth. The sea lamprey continues to be a problem in the Great Lakes and is the focus of much research.Related sites:
Sea Lamprey control, Great Lakes Fishery Commission
GLIN Sea Lamprey in the Great Lakes Region
The Sea Lamprey: No bones about it!
The most serious problems that introduced, non-native species cause are competition and hybridization. Competition for food and habitat is difficult to prove, but is believed to be the cause of population declines of native fish in some situations. Hybridization results when an introduced species mates with a native species producing hybrid offspring. If native species are rare, they are more likely to encounter, mate and reproduce with the invading species than with their own species. This can ultimately lead to the extinction of the native species.
Related TEACH module:
At risk species...
The once common lake sturgeon is also very rare today. The lake sturgeon was once so abundant in the Great Lakes that it was considered a nuisance. However, advances in the smoking and processing industries created a market for smoked sturgeon meat and caviar. Sturgeon were then overfished, and by 1900 populations could no longer support a commercial fishery. Today, these immense fish -- sometimes up to 6 feet (1.8 meters) in length -- are very rare in deep waters of the Great Lakes.Related sites:
About the Lake Sturgeon
Great Lakes Lake Sturgeon Page
Threats to species are everywhere. In the United States alone, 37 percent of freshwater fish species are threatened or have become extinct.
The Committee on the Status of Endangered Wildlife (COSEWIC) in Canada and the Fish and Wildlife Service in the United States determine the status of species, subspecies and separate populations suspected of being at risk from extinction. Species are categorized as follows:
These species no longer exist on Earth!
Formerly found in lakes Erie and Ontario
Declared extinct in 1983
Deepwater cisco (Coregonus johannae)
Harelip sucker (Lagochila lacera)
Longjaw cisco (Coregonus alpenae)
Shortnose cisco (Coregonus reighardi)
Graphics: Bass, muskie, pike and walleye, copyright ŠJoseph Tomelleri; Dr. Nancy Auer and lake sturgeon researchers, Michigan Technological University, Houghton, Mich.