The pollan or Irish pollan (Coregonus pollan) is a freshwater whitefish

Coregonus

Coregonus is a diverse genus of fish in the salmon family . The type species is the common whitefish . The Coregonus species are known as whitefishes...

 that is known only from five Irish

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 lakes, Lough Neagh

Lough Neagh

Lough Neagh, sometimes Loch Neagh, is a large freshwater lake in Northern Ireland. Its name comes .-Geography:With an area of , it is the largest lake in the British Isles and ranks among the forty largest lakes of Europe. Located twenty miles to the west of Belfast, it is approximately twenty...

, Lower Lough Erne

Lough Erne

Lough Erne, sometimes Loch Erne , is the name of two connected lakes in County Fermanagh, Northern Ireland. The lakes are widened sections of the River Erne. The river begins by flowing north, and then curves west into the Atlantic. The southern lake is further up the river and so is named Upper...

, Lough Ree

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 Lough Derg to the south, there are also several minor lakes...

, Lough Derg and Lough Allen

Lough Allen

Lough Allen is a lake situated on the River Shannon, in the north-central part of Ireland, near Ireland's border region. Most of the lake is in County Leitrim, with a smaller portion in County Roscommon. The lake lies to the south of the river's source, near the Iron Mountains, and is the...

.

The pollan populations are threatened by ecosystem changes such as eutrophication and increases in introduced species including pike

Northern Pike

The northern pike , is a species of carnivorous fish of the genus Esox...

, roach

Rutilus

Rutilus is a genus of fishes in the family Cyprinidae, commonly called roaches. Locally, the name "roach" without any further qualifiers is also used for particular species, particularly the Common Roach Rutilus (Latin for "shining, red, golden, auburn") is a genus of fishes in the family...

 and zebra mussel

Zebra mussel

The zebra mussel, Dreissena polymorpha, is a small freshwater mussel. This species was originally native to the lakes of southeast Russia being first described in 1769 by a German zoologist Peter Simon Pallas in the Ural, Volga and Dnieper rivers. They are still found nearby, as Pontic and Caspian...

. Only the population of Lough Neagh in Northern Ireland

Northern Ireland

Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...

 remains abundant and supports a small commercial fishery. The other UK population in Lough Erne has severely declined. The Lough Allen population was only confirmed for the first time in 2006. Other populations rely on stocking for their survival.

In scientific literature and in 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

Siberia

Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...

, Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

, and Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 and is there known as the Arctic cisco

Arctic Cisco

Arctic cisco is an anadromous species of freshwater whitefish that inhabits the Arctic parts of Siberia, Alaska and Canada. It also 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...

 or Siberian omul. C. autumnalis is not distributed elsewhere in northwestern Europe, and the pollan are sometimes given a subspecies status as Coregonus autumnalis pollan. These classifications are based on the close genetic similarity of the Arctic and Irish whitefish populations. By IUCN , the Irish pollan is however listed as a distinct fish species Coregonus pollan, whereas FishBase

FishBase

FishBase is a comprehensive database of information about fish species . It is the largest and most extensively accessed online database on adult finfish on the web...

refers to it alternatively as a species or as part of the Arctic C. autumnalis.

Unlike its Arctic relatives, the Irish pollan does not migrate to the sea.