Evidence of the winter occurrence of the whitefish Coregonus pollan Thompson, 1835 in the Shannon River, Ireland

Abstract

Coregonus pollan Thompson, 1835 is an Irish endemic whitefish with five known lake populations. Lough Derg has the most downstream population of three lakes in the Shannon catchment. We report on the occurrence of recently hatched larvae from a river section captured above Lough Derg during March 2011. This is the first indication of a downstream movement of larval pollan to a lake, which could have important implications for conservation of this red-listed teleost. This finding is consistent with earlier reports of adult pollan, in spawning condition, captured in fyke nets upstream of Lough Derg. There are also accounts of pollan spawning in the river section below Lough Derg during the 1960s, when they were once common.