The pollan or Irish pollan (''Coregonus pollan'' or ''Coregonus autumnalis''
IFI Inland Fisheries Ireland (accessed 1 June 2015)) is a freshwater whitefish known only from five

Irish Irish may refer to: Common meanings * Someone or something of, from, or related to: ** Ireland, an island situated off the north-western coast of continental Europe ***Éire, Irish language name for the isle ** Northern Ireland, a constituent unit ...

lakes,

Lough Neagh Lough Neagh ( ) is a freshwater lake in Northern Ireland and is the largest lake in the island of Ireland, the United Kingdom and the British Isles. It has a surface area of and supplies 40% of Northern Ireland's water. Its main inflows come ...

, Lower

Lough Erne Lough Erne ( , ) is the name of two connected lakes in County Fermanagh, Northern Ireland. It is the second-biggest lake system in Northern Ireland and Ulster, and the fourth biggest in Ireland. The lakes are widened sections of the River Erne, ...

Lough Ree Lough Ree () is a lake in the midlands of Ireland, the second of the three major lakes on the River Shannon. Lough Ree is the second largest lake on the Shannon after Lough Derg. The other two major lakes are Lough Allen to the north, and Lou ...

, Lough Derg and

Lough Allen Lough Allen () is a lake on the River Shannon in northeastern Connacht, Ireland. Most of the lake is in County Leitrim, with a smaller part in County Roscommon. The lake lies to the south of the River Shannon's source, near the Iron Mountains, ...

. The pollan faces competition from introduced species such as

pike Pike, Pikes or The Pike may refer to: Fish * Blue pike or blue walleye, an extinct color morph of the yellow walleye ''Sander vitreus'' * Ctenoluciidae, the "pike characins", some species of which are commonly known as pikes * ''Esox'', genus o ...

, roach and

zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel. 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 ma ...

, and the populations rely on restocking for survival.

Conservation status

The pollan populations are threatened by ecosystem changes such as

eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...

and increases in species, including

, roach and

. Only the population of Lough Neagh in

Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label=Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. North ...

remains abundant and supports a small commercial fishery. The other Northern Irish population in Lough Erne has severely declined. The Lough Allen population was only confirmed for the first time in 2006.Harrison, A.J., Kelly, F.L., Rosell, R.S., Champ, T.W.S., Connor, L. and Girvan, J.R. (2010
First record and initial hydroacoustic stock assessment of pollan ''Coregonus autumnalis'' Pallas in Lough Allen, Ireland.
Biology and Environment: Proceedings of the Royal Irish Academy 110B, 69-74. Other populations rely on stocking for their survival.Freyhof, J. & Kottelat, M. (2008
''Coregonus pollan''
IUCN Red List of Threatened Species. Version 2010.1. Downloaded 25 April 2010.

Description

The Irish pollan and other members of the ''

Coregonus ''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 ty ...

'' genus are very like

herring Herring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Ocea ...

s 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 and a weight of .

Ecology

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.

Classification

In scientific literature and national biodiversity and conservation assessments, the Irish pollan are usually classified within the species ''

Coregonus autumnalis Arctic cisco (''Coregonus autumnalis''), also known as omul russian: Омуль, is an anadromous species of freshwater whitefish that inhabits the Arctic parts of Siberia, Alaska and Canada. It has a close freshwater relative in several lakes of ...

''. That is a widespread

anadromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousan ...

whitefish which inhabits coastal waters and rivers of Arctic

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part o ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...

, and

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

and is there known as the

Arctic cisco Arctic cisco (''Coregonus autumnalis''), also known as omul russian: Омуль, is an anadromous species of freshwater whitefish that inhabits the Arctic parts of Siberia, Alaska and Canada. It has a close freshwater relative in several lakes of ...

or Siberian omul. ''C. autumnalis'' is not distributed elsewhere in northwestern Europe, and the pollan are often given a status of subspecies as ''Coregonus autumnalis pollan''.Ferguson, A
Northern Ireland Priority Species: ''Coregonus autumnalis pollan'' – Pollan
habitats.org.uk (read April 2010) These classifications are based on the close genetic similarity of the Arctic and Irish whitefish populations.Politov, D.V., Gordon, N.Y., & Makhrov, A.A. (2002). Genetic identification and taxonomic relationships of six Siberian species of Coregonus. Archiv für Hydrobiologie: Special Issues Advances in Limnology 57, 21-34. By IUCN and in the

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

, the Irish pollan is, however, listed as a distinct fish species ''Coregonus pollan''. Unlike its Arctic relatives, the Irish pollan does not migrate to the sea.

References

External links

* * {{Taxonbar, from=Q3757988 Coregonus Endemic fauna of Ireland Fish described in 1835