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. (Becker, 1983; Luna, 2008; Michigan Department of Natural Resources, 2008)
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. (Becker, 1983; Luna, 2008; Michigan Department of Natural Resources, 2008)
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. (Becker, 1983)
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. (Becker, 1983)
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. (Becker, 1983)
Lake whitefish males and females do not care for their young after the eggs have been fertilized.
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. (Becker, 1983; Luna, 2008)
Lake whitefish are fairly sedentary in the Great Lakes, although they make seasonal movements between deep and shallow water. They typically make 4 short, seasonal migrations: from deep to shallow water in the spring, back to deep water in summer as water temperatures rise, to spawning areas in shallow water in the fall and early winter, and back to deep water in the winter. Lake whitefish are social and are always found in schools. (Luna, 2008; Michigan Department of Natural Resources, 2008)
Total distances traveled during migrations have been recorded at 8 to 242 km, but the vast majority of fish do not travel more than 40 km. Schools of lake whitefish seem to remain fairly local in their movements. (Becker, 1983)
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.
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. (Becker, 1983; Luna, 2008; Michigan Department of Natural Resources, 2008)
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. (Michigan Department of Natural Resources, 2008)
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. (Michigan Department of Natural Resources, 2008)
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. (Luna, 2008; Michigan Department of Natural Resources, 2008)
There are no adverse effects of lake whitefish on humans.
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. (Becker, 1983; Michigan Department of Natural Resources, 2008)
Tanya Dewey (author), Animal Diversity Web.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
Becker, G. 1983. Fishes of Wisconsin. Madison, Wisconsin: The University of Wisconsin Press.
Luna, S. 2008. "Coregonus clupeaformis" (On-line). fishbase.org. Accessed December 11, 2008 at http://www.fishbase.org/Summary/SpeciesSummary.php?id=234.
Michigan Department of Natural Resources, 2008. "Lake Whitefish, Coregonus clupeaformis" (On-line). Michigan Department of Natural Resources, Fish Identification. Accessed December 11, 2008 at ttp://www.michigan.gov/dnr/0,1607,7-153-10364_18958-45680--,00.html.