Some observations on the behaviour of lake-dwelling brown trout in Lower Lough Erne

Abstract

Acoustic telemetry was utilised to track a sample of 80 adult wild brown trout across an extensive array of 30 receivers in Lower Lough Erne during 2016 and 2017. The mean detection duration across the array was 142 days, and the majority of tagged fish were detected consistently in the northern basin of the lake. One year after tagging, c.40% of larger fish (>45cm LF) were still actively detected, while only 5-10% of smaller fish (<45cm LF) were detected on the array. In total, nine trout were recaptured by anglers between 2 and 1,152 days post-tagging, with a mean liberty time of 152 days, and a minimum angling exploitation rate of 11.25%. A high proportion of surviving tagged trout (>50%) did not undertake spawning migrations into an influent tributary and remained active within the lake during the reproductive period in November. In total, fourteen tagged trout undertook spawning migrations into a range of tributaries; the mean spawning sojourn was 54 days, and five fish (36%) did not return to the lake post spawning.