Lake whitefish average 457 mm in length, although there is large variation in size in local populations. They are covered in scales that range from pea green or almost brown dorsally to silvery white ventrally. The sides have a bluish hue and the fins are nearly transparent. There are two dorsal fins, including an adipose fin which is sometimes larger in males. Dorsal and anal fin rays are usually 11 (range 10-12), pectoral fin rays are from 14 to 17. The nose is blunt, with a small, subterminal mouth. Lake whitefish are long and laterally compressed, as are most salmonids. Males and females have breeding tubercles on the head and body. The maximum recorded weight was 19 kg (Lake Superior, 1918), although lake whitefish are considered very large at 9 kg. Average weight is more like 1.8 kg. The maximum recorded length was 100 cm, all individuals longer than 467 mm are considered mature adults.
Range mass: 19 (high) kg.
Average mass: 1.8 kg.
Range length: 1000 (high) mm.
Average length: 457 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes shaped differently
Lake whitefish eggs are eaten by a host of other fish, including yellow perch, ciscoes, and other whitefish. Juvenile lake whitefish are also eaten by a host of larger, predatory fish, including lake trout, northern pike, burbot, and walleye. Adult lake whitefish are largely preyed on by humans.
Known Predators:
Anti-predator Adaptations: cryptic
Most mortality of lake whitefish occurs at the egg and larval stages. Only about 13% of eggs survive to become larvae and larvae are heavily preyed on by larger fish. The maximum recorded age of a lake whitefish was 50 years old, although maximum ages of 25 years are more typical.
Range lifespan
Status: wild: 50 (high) years.
Typical lifespan
Status: wild: 25 (high) years.
Lake whitefish are found mainly in large, cold, freshwater lakes and their drainage basins. They may occasionally enter brackish water. They make small, seasonal migrations between different water depths. They are found in deeper water in summer and winter, returning to shallower water in spring and then again in fall or early winter to spawn over rocky shoals and reefs along lakeshores. They can be found at water depths from 5 to 128 meters or deeper, although ranges of 15 to 37 meters are more typical.
Range depth: 5 to 110 m.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: lakes and ponds; rivers and streams
Lake whitefish are found throughout northern North America. They are found in cold waters from the Great Lakes north through almost all of Canada and into Alaska.
Biogeographic Regions: nearctic (Native )
Lake whitefish have small mouths and eat mainly small prey, including aquatic insects (Diptera larvae, Trichoptera larvae, Chironomidae larvae, Hexagenia nymphs, Corixidae), amphipods (mainly Pontoporeia and Mysis), mollusks (Sphaerium and Amnicola especially), and fish eggs and fry. They have been recorded eating small alewives and sculpin. They forage mainly on or near the lake bottom.
Animal Foods: fish; eggs; insects; mollusks; aquatic crustaceans
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods, Molluscivore )
Lake whitefish have long formed the basis for important subsistence and commercial fisheries. They are not commonly sought as gamefish, although more anglers are beginning to seek them out. They are difficult to catch with hooks because of the deep water they sometimes inhabit and small mouths. Lake whitefish flesh is considered delicate and delicious and the roe is valued for caviar.
Positive Impacts: food
Some researchers consider lake whitefish conspecific with Baltic whitefish (Coregonus lavaretus).
Like most fish, lake whitefish have a lateral line system that allows them to detect water movement. They also have good vision and sense of smell. In mating, tactile cues may be important as males and females coordinate to release eggs and sperm.
Communication Channels: tactile
Perception Channels: visual ; tactile ; vibrations ; chemical
Overfishing and environmental degradation caused a near collapse of lake whitefish fisheries in the Great Lakes during the early part of the 20th century. Water quality improvement and fishery management has improved populations since then, although local populations remain threatened and the health of lake whitefish stocks has not fully recovered under continuing commercial fishing pressure.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Lake whitefish spawn over shallow water shoals. Spawning occurs in fall and early winter and the eggs are broadcast over the shoals, where they settle to the bottom. Eggs hatch in March or early April, taking about 133 days to hatch in waters averaging 1.7 degrees Celsius. Time to hatching increases with decreasing water temperature. In laboratory settings, optimum water temperature for incubation is 3.2 to 8.1 degrees Celsius. Hatching took only 41.7 days in water at 10 degrees Celsius, and 182 days at 0.5 degrees Celsius. Larvae average 13.25 mm in length at hatching and grow about 25 mm per month in their first season. There is little known about lake whitefish development between the larval and adult stages.
There are no adverse effects of lake whitefish on humans.
Lake whitefish are both important prey, as eggs and young, for many other fish species, and important predators of aquatic insects, mollusks, and crustaceans. Lake whitefish are parasitized by introduced sea lampreys.
Lake whitefish spawn in large groups over shallow water shoals in fall and early winter. Spawning occurs at night. Females repeatedly rise to the water's surface while releasing eggs. They are accompanied by either one or two males who simultaneously release their milt onto the eggs. Spawning is accompanied by a lot of jumping and surface activity.
Mating System: polygynandrous (promiscuous)
Lake whitefish spawn in the fall or early winter and eggs hatch in the early spring. Females release thousands of eggs when they spawn, the number of eggs depends on body size. One female that weighed 907 g had 25,000 eggs and another female that weighed 5.9 kg had 130,000 eggs. Males mature at a minimum length of 368 mm, females at 419 mm.
Breeding interval: Lake whitefish breed once yearly.
Breeding season: Spawning occurs in fall or early winter.
Average gestation period: 133 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Lake whitefish males and females do not care for their young after the eggs have been fertilized.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)
The lake whitefish (Coregonus clupeaformis) is a species of freshwater whitefish from North America. Lake whitefish are found throughout much of Canada and parts of the northern United States, including all of the Great 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.[3] 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.[4]
The scientific genus name Coregonus (co-regg'-on-us) means "angle eye" in Greek and the species name clupeaformis means "herring-shaped" in Latin.[3]
Lake whitefish are similar in appearance to other whitefishes in the Coregoninae subfamily of the salmon family Salmonidae, such as the northern cisco (Coregonus artedi). As with all salmonids, they have an adipose fin.[5] To the distinction from cisco, 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 the mooneye due to the small posterior dorsal adipose fin.[6] Another notable feature of the lake whitefish is the presence of two small flaps in each nostril.[7] 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.[3] The tail fin of the lake whitefish is severely forked, making it a fast swimmer.
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.[8] On average, the lake whitefish weighs only 4 pounds. They can grow to 31 inches (79 cm) and commonly reach 20 inches (51 cm).[7]
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 from Alaska and western Canada to the Atlantic coastal drainage of Maine and in New Brunswick north to Labrador.[7]
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.[7] In northwestern Canada, a large spawning migration enters the Athabasca Delta in late summer, moving upstream in the Athabasca River. The longest single movement of a tagged whitefish ever recorded was 388 km (241 mi), from Fort McMurray to the north shore of Lake Athabasca in Alberta, Canada.
Fish of larval and postlarval stages feed on plankton. Once the larvae reach 3–4 inches (76–102 mm) they switch to feeding on bottom-dwelling animals (snail, insect larvae, zebra mussels, and fingernail clams) which they will consume for the remainder of their lives.[8] In late June and July, some inland lake populations of ciscoes and lake whitefish leave the deep, cool waters to feast on emerging mayflies and midges.[7] The lake whitefish's natural predators include burbot, lake trout, and northern pike.
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 the FAO.[9]
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 1981-1999. 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.
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 fishing has allowed for the spread of this fish into many different markets, restaurants, and grocery store shelves. [7]
A major threat to the lake whitefish is an invasive parasite species, the sea lamprey. It is one of a number of species (in addition to the lake trout and lake 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 the Great Lakes region through the Erie Canal which opened in 1825.[10] and spread even further in 1919 with improvements to the Welland Canal from Lake Ontario to Lake Erie, Lake Michigan, Lake Huron, and Lake Superior.
Since the end of the last glaciation (about 12,000 years ago), whitefish have re-colonized many North American lakes, from different directions, from refugia that 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 main ecotypes are recognized within the species: a normal and a dwarf ecotype. These normal and dwarf ecotypes are mainly differentiated by the benthic and pelagic zone they occupy, respectively. Normal whitefish also grow much bigger and live much longer than the dwarf ecotype.
Many of these populations live in sympatry, 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.
The lake whitefish (Coregonus clupeaformis) is a species of freshwater whitefish from North America. Lake whitefish are found throughout much of Canada and parts of the northern United States, including all of the Great 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.
