FIRST RECORD AND INITIAL HYDROACOUSTIC STOCK ASSESSMENT OF POLLAN COREGONUS AUTUMNALIS PALLAS IN LOUGH ALLEN, IRELAND

The Irish Pollan Coregonus autumnalis Pallas is unique in western Europe, with its current known distribution being limited to four lakes in Ireland; Lough Neagh and Lower Lough Erne in Northern Ireland and Lough Ree and Lough Derg in the Republic of Ireland. In this paper we report the first authenticated record of pollan in a fifth Irish lake—Lough Allen, County Leitrim. Using hydroacoustic technology, combined with a ground-truth gill netting survey, abundance estimates show that the population is relatively small, numbering in the region of several thousand individuals. Captured fish ranged in age from 1+ to 4+, indicating reproductive success in each year over the previous four years. Threats to sensitive species such as pollan include eutrophication, competition with introduced species, land drainage and the resulting siltation of downstream lakes. Further detailed investigations on the status of this newly discovered population, including location of spawning sites, recruitment success and genetic relationship with other Irish populations, are crucial in informing management decisions with a view to protecting this unique and threatened fish species.