Kiyi
Encyclopedia
The kiyi is a species
of freshwater whitefish
, a deepwater cisco
, endemic to the Great Lakes
of North America. It previously inhabited Lake Superior
, Lake Michigan
, Lake Huron
and Lake Ontario
, but is now believed to persist only in Lake Superior where it is common. The various deepwater ciscos are also called chub
s (not to be confused with the various species of Cyprinidae also called chubs). The kiyi is part of the large group of related northern ciscos known as the Coregonus artedi complex.
of kiyi have been recognised based on morphological characteristics and distribution. The nominate subspecies Coregonus kiyi kiyi, or the Upper Great Lakes kiyi, was found in Lakes Superior, Huron and Michigan. The Lake Ontario kiyi, C. kiyi orientalis, was only found in Lake Ontario. However, recent examination of the ciscos as a group using genetic techniques has suggested that some recognized species are not genetically distinct form others, and it has been suggested that the deepwater ciscos in general may be forms of the northern cisco C. artedi adapted to life in different ecological niches. The distinction between the subspecies of kiyi has been rendered academic, however, by the extinction of the Lake Ontario form, which has not been seen since the 1960s and has been extinct since 2005. The subspecies was driven to extinction by commercial exploitation, predation and competition by introduced species.
Females are known to grow larger and live longer (10 years) than males (8 years). Age at maturity is believed to be 2 to 3 years. The minimum size at maturity is reported as 132 millimetres (5.2 in) in Lake Superior. Spawning takes place in autumn or early winter, and has been reported in depths of 106 –. Ciscoes are known to exhibit large fluctuations in reproductive success and will produce several years of strong year classes followed by several years of poor reproductive success.
Although not the preferred chub species owing to their relatively small size, kiyi were a substantial component of the Great Lakes chub fisheries at one time, particularly in Lake Ontario. They, along with other deepwater chubs, have been negatively affected by a combination of factors, including the invasion of the Great Lakes by several non-native species that prey on various life stages of the chubs or compete with them. Parasitic sea lamprey
(Petromyzon marinus, alewife
(Alosa pseudoharengus) and rainbow smelt
(Osmerus mordax), in particular, have been implicated in their demise, and are believed to have stressed populations to the extent that previously sustainable levels of exploitation became unsustainable.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of freshwater whitefish
Freshwater whitefish
The freshwater whitefish are fish of the subfamily Coregoninae in the salmon family Salmonidae. Along with the freshwater whitefish, the Salmonidae includes the freshwater and anadromous trout and salmon species as well as graylings...
, a deepwater cisco
Cisco (fish)
The ciscoes are salmonid fish of the genus Coregonus that differ from other members of the genus in having upper and lower jaws of approximately equal length and high gillraker counts...
, endemic to the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
of North America. It previously inhabited Lake Superior
Lake Superior
Lake Superior is the largest of the five traditionally-demarcated Great Lakes of North America. It is bounded to the north by the Canadian province of Ontario and the U.S. state of Minnesota, and to the south by the U.S. states of Wisconsin and Michigan. It is the largest freshwater lake in the...
, Lake Michigan
Lake Michigan
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
, Lake Huron
Lake Huron
Lake Huron is one of the five Great Lakes of North America. Hydrologically, it comprises the larger portion of Lake Michigan-Huron. It is bounded on the east by the Canadian province of Ontario and on the west by the state of Michigan in the United States...
and Lake Ontario
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
, but is now believed to persist only in Lake Superior where it is common. The various deepwater ciscos are also called chub
Chub
The European chub , sometimes called the round chub, fat chub, chevin, pollard or simply "the" chub, is a freshwater fish of the family Cyprinidae...
s (not to be confused with the various species of Cyprinidae also called chubs). The kiyi is part of the large group of related northern ciscos known as the Coregonus artedi complex.
Description
The kiyi is one of the smaller ciscos. Adult kiyi average approximately 250 millimetres (9.8 in) in total length and 170 grams (6 oz) in weight. Individuals can reach more than 280 millimetres (11 in). They are silvery pink or purple iridescence, darker on the back and white on the belly. They may have a dark tip on the lower jaw. They have a large head and a conspicuous, large eye.Subspecies
Two subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of kiyi have been recognised based on morphological characteristics and distribution. The nominate subspecies Coregonus kiyi kiyi, or the Upper Great Lakes kiyi, was found in Lakes Superior, Huron and Michigan. The Lake Ontario kiyi, C. kiyi orientalis, was only found in Lake Ontario. However, recent examination of the ciscos as a group using genetic techniques has suggested that some recognized species are not genetically distinct form others, and it has been suggested that the deepwater ciscos in general may be forms of the northern cisco C. artedi adapted to life in different ecological niches. The distinction between the subspecies of kiyi has been rendered academic, however, by the extinction of the Lake Ontario form, which has not been seen since the 1960s and has been extinct since 2005. The subspecies was driven to extinction by commercial exploitation, predation and competition by introduced species.
Ecology and behavior
The kiyi is reportedly most abundant at depths greater than 80 metres (262.5 ft) over its range, with Lake Superior kiyi said to be abundant at depths of 180 metres (590.6 ft).Females are known to grow larger and live longer (10 years) than males (8 years). Age at maturity is believed to be 2 to 3 years. The minimum size at maturity is reported as 132 millimetres (5.2 in) in Lake Superior. Spawning takes place in autumn or early winter, and has been reported in depths of 106 –. Ciscoes are known to exhibit large fluctuations in reproductive success and will produce several years of strong year classes followed by several years of poor reproductive success.
Although not the preferred chub species owing to their relatively small size, kiyi were a substantial component of the Great Lakes chub fisheries at one time, particularly in Lake Ontario. They, along with other deepwater chubs, have been negatively affected by a combination of factors, including the invasion of the Great Lakes by several non-native species that prey on various life stages of the chubs or compete with them. Parasitic sea lamprey
Sea lamprey
The sea lamprey is a parasitic lamprey found on the Atlantic coasts of Europe and North America, in the western Mediterranean Sea, and in the Great Lakes. It is brown, gray, or black on its back and white or gray on the underside and can grow up to 90 cm long. Sea lampreys prey on a wide...
(Petromyzon marinus, alewife
Alewife
The alewife is a species of herring. There are anadromous and landlocked forms. The landlocked form is also called a sawbelly or mooneye...
(Alosa pseudoharengus) and rainbow smelt
Rainbow smelt
The rainbow smelt, Osmerus mordax, is an anadromous species of fish of the family Osmeridae. The distribution of Osmerus mordax is circumpolar. The rainbow smelt was introduced to the Great Lakes, and from there has made its way to various other places. Walleye, trout, and other larger fish prey on...
(Osmerus mordax), in particular, have been implicated in their demise, and are believed to have stressed populations to the extent that previously sustainable levels of exploitation became unsustainable.