Pollan | |
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VU (Irish Red List) [2] | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Salmoniformes |
Family: | Salmonidae |
Genus: | Coregonus |
Species: | C. pollan |
Binomial name | |
Coregonus pollan W. Thompson, 1835 | |
Synonyms | |
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The pollan [4] or Irish pollan [3] (Coregonus pollan [3] or Coregonus autumnalis [4] ) is a freshwater whitefish known only from five Irish lakes, Lough Neagh, Lower Lough Erne, Lough Ree, Lough Derg and Lough Allen. The pollan faces competition from introduced species such as pike, roach and zebra mussel, and the populations rely on restocking for survival.
The pollan populations are threatened by ecosystem changes such as eutrophication and increases in species, including pike, roach and zebra mussel. [5] Only the population of Lough Neagh in Northern Ireland remains abundant and supports a small commercial fishery. The other Northern Irish population in Lough Erne has severely declined. [5] The Lough Allen population was only confirmed for the first time in 2006. [6] Other populations rely on stocking for their survival. [1]
The Irish pollan and other members of the Coregonus genus are very like herrings in appearance but the presence of an adipose fin distinguishes them. The mouth is relatively small and the teeth are deciduous and very small. The scales are of moderate size, the dorsal fin is of moderate length and the tail fin deeply forked. The different species are difficult to tell apart unless the lake from which they originated is known. This species grows to an average length of 9 to 10 in (22.9 to 25.4 cm) and a weight of 6 ounces (170 g). [7]
The Irish pollan is a shoaling species. The diet consists small crustaceans and insect larvae. Breeding takes place in November and December, with spawning taking place over hard ground in deep water. [7]
In scientific literature and national biodiversity and conservation assessments, the Irish pollan are usually classified within the species Coregonus autumnalis . That is a widespread anadromous whitefish which inhabits coastal waters and rivers of Arctic Siberia, Alaska, and Canada and is there known as the Arctic cisco or Siberian omul. [4] [6] [8] [9] C. autumnalis is not distributed elsewhere in northwestern Europe, and the pollan are often given a status of subspecies as Coregonus autumnalis pollan. [5] [10] These classifications are based on the close genetic similarity of the Arctic and Irish whitefish populations. [11] [12] [13] By IUCN and in the FishBase, the Irish pollan is, however, listed as a distinct fish species Coregonus pollan. [1] [3]
Unlike its Arctic relatives, the Irish pollan does not migrate to the sea. [7]
Coregonus is a diverse genus of fish in the salmon family (Salmonidae). The Coregonus species are known as whitefishes. The genus contains at least 68 described extant taxa, but the true number of species is a matter of debate. The type species of the genus is Coregonus lavaretus.
Coregonus lavaretus is a species of freshwater whitefish, in the family Salmonidae. It is the type species of its genus Coregonus.
The zebra mussel is a small freshwater mussel, an aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally introduced to numerous other areas and has become an invasive species in many countries worldwide. Since the 1980s, the species has invaded the Great Lakes, Hudson River, Lake Travis, Finger Lakes, Lake Bonaparte, and Lake Simcoe. The adverse effects of dreissenid mussels on freshwater systems have led to their ranking as one of the world's most invasive aquatic species.
The ciscoes are salmonid fish that differ from other members of the genus Coregonus in having upper and lower jaws of approximately equal length and high gill raker counts. These species have been the focus of much study recently, as researchers have sought to determine the relationships among species that appear to have evolved very recently. Cisco is also specifically used for the North American species Coregonus artedi, also known as lake herring.
The powan is a kind of freshwater whitefish endemic to two lochs in Scotland, Loch Lomond and Loch Eck. It has been successfully introduced in two other sites, Loch Sloy and the Carron Valley Reservoir.
The omul, Coregonus migratorius, also known as Baikal omul, is a whitefish species of the salmon family endemic to Lake Baikal in Siberia, Russia. It is considered a delicacy and is the object of one of the largest commercial fisheries on Lake Baikal. In 2004, it was listed by an unknown group in Russia as an endangered species.
Coregonus albula, known as the vendace or as the European cisco, is a species of freshwater whitefish in the family Salmonidae. It is found in lakes in northern Europe, especially Finland, Latvia, Lithuania, Sweden, Russia and Estonia, and in some lakes of Norway, the United Kingdom, northern Germany, and Poland. It is also found in diluted brackish water in the Gulfs of Finland and Bothnia, both of which are in the Baltic Sea.
The Arctic cisco, also known as Arctic omul, is an anadromous species of freshwater whitefish that inhabits the Arctic parts of Siberia especially Yenisey Gulf. It can also be found in Alaska and Canada. It has a close freshwater relative in several lakes of Ireland, known as the pollan, alternatively regarded as conspecific with it, or as a distinct species.
The broad whitefish is a freshwater whitefish species. Dark silvery in colour, and like a herring in its shape. Its distinctive features includes: a convex head, short gill rakers, and a mild overbite. It is found in the Arctic-draining streams, lakes, and rivers of far eastern Russia and North America. Its prey includes larval insects, snails, and shellfish. It is eaten by humans and brown bears.
Coregonus sardinella, known as the least cisco or the sardine cisco, is a fresh- and brackishwater salmonid fish that inhabits rivers, estuaries and coastal waters of the marginal seas of the Arctic Basin, as well as some large lakes of those areas.
The round whitefish is a freshwater species of fish that is found in North American drainages from Alaska to New England, including the Great Lakes except for Lake Erie, and in Arctic tributaries of northeast Asia, as well as northern Kamchatka Peninsula and the northern coasts of the Sea of Okhotsk. It has an olive-brown back with light silvery sides and underside and its length is generally between 9 and 19 inches. They are bottom feeders, feeding mostly on invertebrates, such as crustaceans, insect larvae, and fish eggs. Some other fish species, like white sucker in turn eat their eggs. Lake trout, northern pike and burbot are natural predators. Other common names of the round whitefish are Menominee, pilot fish, frost fish, round-fish, and Menominee whitefish. The common name "round whitefish" is also sometimes used to describe Coregonus huntsmani, a salmonid more commonly known as the Atlantic whitefish.
The freshwater whitefish are fishes of the subfamily Coregoninae, which contains whitefishes and ciscoes, and is one of three subfamilies in the salmon family Salmonidae. Apart from the subfamily Coregoninae, the family Salmonidae includes the salmon, trout, and char species of the subfamily Salmoninae, and grayling species of the subfamily Thymallinae. Freshwater whitefish are distributed mainly in relatively cool waters throughout the northern parts of the Northern Hemisphere.
The Bering cisco or Lauretta whitefish is a freshwater whitefish found in Alaska and part of Russia. It is often considered to be the same species as the more common Arctic cisco.
The lake whitefish 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.
Garadice Lough (Irish: Loch Guth Ard Deas, also known as Garadice Lake or Lough Garadice, is a freshwater lake in County Leitrim, Ireland. It is located in the south of the county and now forms part of the Shannon–Erne Waterway.
St. John's Lough, also known as St. John's Lake, is an irregularly shaped freshwater lake located in south County Leitrim, in northwest of Ireland. The lake forms part of the wider Shannon–Erne Waterway tourist attraction. The ecology of John's Lough, and the Shannon-system, is threatened by pollution and invasive species such as curly waterweed, zebra mussel, and freshwater clam.
Carrickaport lough is a freshwater lake in Kiltubrid parish, south County Leitrim, Ireland. Drumcong village, and Lough Scur, lie nearby. Carrickaport lough is known for quality bream and pike fishing. The ecology of Carrickaport lough, and other county waterways, is threatened by curly waterweed, zebra mussel, and freshwater clam invasive species.
Keshcarrigan Lough is a mesotrophic freshwater lake near Keshcarrigan in County Leitrim, Ireland. Known for quality coarse fishing, the lake allows bank fishing from concrete stands on the northern shore, two with wheelchair access. The ecology of Keshcarrigan Lough, and other county waterways, is threatened by curly waterweed, zebra mussel, and freshwater clam invasive species.
Lough Conway is a very small freshwater lake in northwest Ireland.