Coregonus kiyi
Kiyi

Kiyi, Coregonus kiyi, are found only in the Great Lakes between the United States and Canada. They are commonly found in Lake Superior but are rare in Lake Huron and Lake Ontario and endangered in Lake Michigan. None are found in Lake Erie. COSEWIC considers this species as extirpated in all Great Lakes except Lake Superior. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005; Eakins, 2011; Froese, et al., 2011)

Found only in the Laurentian Great Lakes of North America, kiyi require a freshwater climate and reside at depths of 35 to 200 m. Although they are occasionally found in shallower waters, kiyi prefer waters of at least 108 m in depth. They are found in water of temperatures ranging from 3.7 to 4.6 ˚C. Kiyi live in clear, dark water and have been collected over bottoms of clay and mud substrate. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005; Carlander, 1969; Eakins, 2011; Froese, et al., 2011)

Kiyi are long, thin, elliptically shaped, and laterally compressed fish. They are covered in large silvery scales. Although coloration varies, they are generally dark on the top, silvery on the side, and white on the underside. Purple and pink iridescence is noticeable. Kiyi average 25 cm in length and can range from 12 to 35 cm in length. The head comprises roughly a quarter of the length. They have large eyes, and the lower jaw may protrude beyond the upper jaw or be terminal. Gill rakers are of medium to long length and number from 40 to 45. The spine is comprised of 55 to 58 vertebrae, and their lateral line has 71 to 91 scales. Kiyi have 9 to 11 dorsal soft rays, 9 to 16 anal soft rays, 15 to 18 pectoral soft rays, 11 to 12 pelvic soft rays, and a forked caudal fin. Kiyi weigh between 0.4 and 0.16 kg. Kiyi are similiar in appearance to other species of ciscos, but are easily distinguished by their large eyes and paired fins.

Pictures can be seen at the Wisconsin Department of Natural Resources website. (Froese, et al., 2011; Hubbs and Lagler, 2004; "Kiyi (Upper Great Lakes Population)", 2008; "Kiyi (Coregonus kiyi)", 2009a)

Coregonus kiyi is split into two subspecies: upper Great Lakes kiyi, Coregonus kiyi kiyi, located in Lake Superior and Coregonus kiyi orientalis, once located in Lake Ontario. Upper Great Lakes kiyi have fewer gill-rakers, a longer head, and longer paired fins. In May 2005, Coregonus kiyi orientalis was declared extinct due to predation, competition, and over-harvest from commercial fishing. ("Kiyi (Upper Great Lakes Population)", 2008)

Little information is avaiable regarding the development of kiyi. However, development is likely similiar to that of other members of the genus, such as lake whitefish. Female lake whitefish gain weight faster and are heavier than males, though they are generally the same length. Lake whitefish eggs incubate for 120 to 140 days and hatch in March or April. Hatchlings reach a length of 13 mm by 3 weeks of age. Mortality of lake whitefish fry is 87%. Growth is initially relatively slow and increases from June to the end of July. In laboratory tests, lake whitefish eggs did not survive at temperatures below 0˚C or above 12˚C. Egg mortality increased with increasing temperature. Incubation time decreased with increasing temperature. (Carlander, 1969)

Kiyi are lithopelagophils, meaning they spawn over open gravelly areas. They practice external fertilization, and eggs are scattered across the substrate. Little information is otherwise available regarding the mating systems of kiyi, however, they are likely similiar to that of other members of the genus. Lake whitefish males have pronounced breeding tubercles, and they precede females to spawning areas. Spawning is promiscuous and most commonly occurs at night. Eggs and sperm are released near the surface of the water after a display of upward movement. Female lake whitefish release eggs in small batches over a period of ten days. Eggs are described as semi buoyant, non-adhesive, 2 to 3 mm in diameter, and number 53,000 per fluid quart (Carlander 1969). Natural fertilization is about 80%. (Carlander, 1969; Eakins, 2011)

Kiyi generally spawn in the fall. In Lake Superior, spawning occurs from November to December at depths around 128 m. When kiyi populated other lakes, spawning was known to occur from September to January at depths of 106 to 165 m depending on the lake. They practice external fertilization, scattering their eggs across a gravelly substrate. At the time of spawning females are generally heavier than males of the same length. Females loose about 6.2 to 14.4 % (mean 11.8%) of their weight while males lose 0 to 7.4 % (mean 1.6%). Eggs hatch in 120 to 140 days. Kiyi reach maturity at an age of 2 to 3 years, generally at a length of at least 132 mm. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005; Carlander, 1969)

Kiyi do not guard their eggs after spawning, and they are not known to provide parental care after their offspring hatch. (Carlander, 1969; Eakins, 2011)

The lifespan of kiyi is 7 to 8 years for males and 9 to 10 years for females. Females have been known to live more than 10 years. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005; Eakins, 2011)

Little information is available regarding behavior of kiyi. Lake whitefish, also deep cold water fish in the genus, are typically sedentary and spend most of their time in loosely aggregated schools. (Dewey, 2008; Tomelleri and Eberle, 1990)

The movement and home range of kiyi have not been well studied. Lake whitefish, however, have been tagged and their movements monitored. In Lake Erie, individual lake whitefish migrate between deep water and spawning grounds at a distance of 280 km. In Lake Michigan, some individuals traveled farther than 40 km with a maximum distance of 115 km in a year. (Carlander, 1969)

Kiyi have large eyes that are uniquely adapted for their deepwater habitat. Because of their lateral line, they can also sense movement in the surrounding water. Communication among near relatives lake whitefish is tactile. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005; Dewey, 2008)

Kiyi predominantly prey on small freshwater shrimps and may also prey on opossum shrimp, amphipods, mayfly nymphs, mollusks, zooplankton, benthos, and chironomids. More specifically, prey include Pontoporeia, Mysis including Mysis relicta, and Diporeia hoyi. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005; "Lake Superior Food Web", 2009; Carlander, 1969; Hubbs and Lagler, 2004)

Kiyi are preyed upon by burbot and lake trout. Other potential predators include sea lamprey, rainbow smelt, and alewife. Kiyi are also preyed upon by humans. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005)

Kiyi prey upon a variety of zooplankton and macroinvertebrates and also serve as prey for piscivores. ("Lake Superior Food Web", 2009)

Kiyi were once very important commercial fish in the Great Lakes and were heavily fished. Deep-water cisco fishing, commonly referred to as chub fishing, is no longer practiced in the American portion of Lake Superior but still occurs in Canadian waters. Quotas remain well below the mean exploitable biomass and are only roughly one-tenth the estimated present population size. Whitefishes in general make up the largest commercial fishery in the Great Lakes. However, kiyi have low marketability and the demand is generally low. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005; "Coregonus kiyi — kiyi", 2000)

There are no known adverse effects of kiyi on humans. (Froese, et al., 2011)

Kiyi are listed as vulnerable by the IUCN and are considered of special concern by the US Fish and Wildlife service, the states of Michigan, Indiana, Minnesota, Wisconsin, New York, and the Ontario Ministry of Natural Resources.

Overfishing contributed greatly to the extirpation of kiyi in lakes Huron, Michigan and Ontario. Although they are not currently a targeted species, kiyi are occasionally taken as by-catch for other commercial fisheries. Other threats to this species include loss of cold deep-water habitat as well as habitat degradation due to contaminants and sedimentation. This species is particularly vulnerable to these processes as they are endemic to a single lake. Competition with and predation by exotic species such as alewife, smelt, pacific salmon, and sea lamprey are the greatest threat to existing populations of kiyi.

Conservation efforts should focus on the control of exotic species in Lake Superior, and regulation of commercial fisheries that negatively affect kiyi. Additionally, more information is required regarding the abundance of this species.

Reestablishment of this species in Lake Huron and Lake Michigan may be possible using populations from Lake Superior, although this has not yet occurred. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005; "Coregonus kiyi — kiyi", 2000; "Kiyi (Coregonus kiyi)", 2009a; "Kiyi (Coregonus kiyi)", 2009b)

In 1927, kiyi made up roughly 52.8% of all ciscoes caught in experimental gill nets in Lake Ontario. By 1942 they comprised only 0.01%, and only 1 individual was caught in 1964. This was the last recorded presence of kiyi in Lake Ontario. ("Assessment and Update Status Report on the Lake Ontario Kiyi and Upper Great Lakes Kiyi", 2005)