Current status of pollan <i>Coregonus autumnalis</i> pollan in Lough Ree, Ireland

Abstract

The Irish pollan Coregonus autumnalis pollan is a unique and threatened freshwater fish species endemic to the island of Ireland, with its current known distribution limited to five lakes; Lough Neagh, Lower Lough Erne, Lough Allen, Lough Ree and Lough Derg. The Lough Neagh pollan are still relatively abundant, contributing approximately 25% of the total fish abundance. However, populations in Lower Lough Erne and the three Shannon lakes contribute B1% of total fish abundance. As a result, pollan are listed as ‘Endangered’ in the Irish Red Data Book and the IUCN Red List of Threatened Species. Empirical data on pollan population size in Irish lakes is lacking, with current estimates based mainly on expert opinion. The current work combines new hydroacoustic data with an extensive gill netting survey, suggesting an abundance estimate for pollan greater than 10cm in length in Lough Ree to be in excess of 6000 individuals. The age classes 1� and 2� were captured and the hydroacoustic data displayed a strong cohort of 0� fish, indicating reproductive success in the previous three years. This new abundance data contributes significantly to the knowledge of the Lough Ree pollan stock. Future and ongoing monitoring of population size, along with the identification of spawning locations, will help to inform management decisions aimed at protecting this unique and endangered fish species.