Lake whitefish

Lake whitefish
Conservation status
Secure(NatureServe)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Salmoniformes
Family:	Salmonidae
Genus:	Coregonus
Species:	C. clupeaformis
Binomial name
Coregonus clupeaformis (Mitchill,1818)
Range ofC. clupeaformis
Synonyms
List Coregonus albusLesueur, 1818 Coregonus atikamegBajkov, 1933 Coregonus clupeaformissubsp.dustiniKoelz, 1931 Coregonus clupeaformissubsp.gulliveriKoelz, 1931 Coregonus clupeaformissubsp.latusKoelz, 1931 Coregonus clupeaformissubsp.medoraeKoelz, 1931 Coregonus clupeiformis(Mitchill, 1818) Coregonus labradoricus(Richardson, 1836) Coregonus latiorAgassiz, 1850 Coregonus neohantoniensisPrescott, 1851 Coregonus odonoghueiBajkov, 1929 Coregonus sapidissimusAgassiz, 1850 Salmo clupeaformisMitchill, 1818 Salmo labradoricusRichardson, 1836 Salmo otsegoClinton, 1822

Thelake whitefish(Coregonus clupeaformis) is a species offreshwater whitefishfrom North America. Lake whitefish are found throughout much ofCanadaand parts of the northernUnited States,including all of theGreat Lakes.The lake whitefish is sometimes referred to as a "humpback" fish due to the small size of the head in relation to the length of the body.It is a valuable commercial fish, and also occasionally taken by sport fishermen. Smoked, refrigerated, vacuum-packed lake whitefish fillets are available in North American grocery stores. Other vernacular names used for this fish include Otsego bass, Sault whitefish, gizzard fish, common whitefish, eastern whitefish, Great Lakes whitefish, humpback whitefish, inland whitefish and whitefish.

Etymology

The scientific genus nameCoregonus(co-regg'-on-us) means "angle eye" in Greek, and the species nameclupeaformismeans "herring-shaped "in Latin.

Description

Lake whitefish are similar in appearance to other whitefishes in theCoregoninaesubfamily of the salmon familySalmonidae,such as thenorthern cisco(Coregonus artedi). As with all salmonids, they have anadipose fin.To the distinction fromcisco,the lake whitefish has a snout which overhangs the short lower jaw, so that the mouth opens in a slightly inferior position. Thus the fish can feed on the bottom of lake beds or grab food particulates out of the water or from the surface of a water body. The cisco in turn has a short snout with a lower jaw that extends beyond the snout. Both the cisco and lake whitefish are discernible from themooneyedue to the small posterior dorsaladipose fin.In early life stages however, the cisco and lake whitefish are indistinguishable based on morphological characters alone with genetic analyses being necessary to reliably identify species.Another notable feature of the lake whitefish is the presence of two small flaps in each nostril.Their coloration is typically silver to white with an olive to pale-green or brown dorsal hues. The ventral fins are white and the tail has a dark posterior edge.

Lake whitefish from inland lakes can reach a weight upwards of 5 pounds (2,300 g); the largest Lake Whitefish caught on rod and reel weighted 15 pounds 6 oz, from Clear Lake Ontario Canada on May 21, 1983, by Chris T. D. Webster according to the Fresh Water Fishing Hall of Fame, in Hayward Wisconsin.On average, the lake whitefish weighs only 4 pounds. They can grow to 31 inches (79 cm) and commonly reach 20 inches (51 cm).

Life history

Habitat

Lake whitefish are cool water fish. They are found in a large number of inland lakes, and they have been known to enter brackish waters. The lake whitefish is distributed fromAlaskaand western Canada to the Atlantic coastal drainage ofMaineand inNew Brunswicknorth toLabrador.

Reproduction

Lake whitefish spawn from September through January in water two to four metres in depth during the night. In the autumn, mature lake whitefish enter the shallows to lay their eggs on shoals of rubble and gravel. There is no parental care of the young. In the following spring the young will hatch.In northwestern Canada, a large spawning migration enters theAthabasca Deltain late summer, moving upstream in theAthabasca River.The longest single movement of a tagged whitefish ever recorded was 388 km (241 mi), fromFort McMurrayto the north shore ofLake AthabascainAlberta,Canada.

Diet

Fish oflarvaland postlarval stages feed on plankton. Once the larvae reach 3–4 inches (76–102 mm) they switch to feeding on bottom-dwelling animals (snail,insectlarvae,zebra mussels,andfingernail clams) which they will consume for the remainder of their lives.In late June and July, some inland lake populations of ciscoes and lake whitefish leave the deep, cool waters to feast on emergingmayfliesandmidges.The lake whitefish's natural predators includeburbot,lake trout,andnorthern pike.

Fishing

Commercial fishing

Lake whitefish is one of the most important species for commercial inland fisheries in North America. The total annual catch in 1999 from Canada was 8 328 t and USA 5 353 t reported by theFAO.

Lake whitefish is the prime commercial species of the upper Great Lakes fishery, because this delicately flavored fresh fish has high local consumer acceptance. An average of 11 million pounds was harvested from the Great Lakes annually from 1981 to 1999. Although the harvest has declined from 9.5 to 8 million pounds in recent years, prices have not increased. Instead, the price for Great Lakes lake whitefish, which once reached as high as $1.04/lb., currently averages $.75/lb. and has dropped to as low as $.40/lb during periods of high production.

Sports fishing

Many amateur anglers also enjoy hooking this fish in the months of June, July and early August. A simple line and jig system is enough to catch the fish as they feast on mayflies and midges. In winter months, catching whitefish through the ice is very popular, particularly in northern Wisconsin, with many fishing guides specializing in this species. Successful icefishing techniques include using a jigging spoon, with at least one "slider hook" above and separated from the spoon with a barrel swivel, and all hooks tipped with wax worms.Commercial fishinghas allowed for the spread of this fish into many different markets, restaurants, and grocery store shelves.

Conservation

A major threat to the lake whitefish is aninvasiveparasite species, thesea lamprey.It is one of a number of species (in addition to thelake troutandlake herring) aggressively attacked by sea lamprey. In Lake Michigan the sea lamprey began to decimate indigenous fish populations in the 1930s and 1940s. It may have entered theGreat Lakes regionthrough theErie Canalwhich opened in 1825.and spread even further in 1919 with improvements to theWelland CanalfromLake OntariotoLake Erie,Lake Michigan,Lake Huron,andLake Superior.

Evolution

Since the end of thelast glaciation(about 12,000 years ago), whitefish have re-colonized many North American lakes, from different directions, fromrefugiathat represent genetically diverged stocks or races. After the invasions, the whitefish have also diversified into different populations locally, such that now in many lakes two mainecotypesare recognized within the species: a normal and a dwarf ecotype. These normal and dwarf ecotypes are mainly differentiated by thebenthicandpelagiczone they occupy, respectively. Normal whitefish also grow much bigger and live much longer than the dwarf ecotype.

Many of these populations live insympatry,yet are reproductively isolated. The fact that they are young species makes them prime candidate to study the evolutionary forces driving their ecological divergence and reproductive isolation.

External links

• "Coregonus clupeaformis".Integrated Taxonomic Information System.Retrieved18 April2006.
• Lake Whitefish (Coregonus clupeaformis)Government of Alberta, Sustainable Resources Department.