Juvenile recruitment and smolt output of brown trout ( Salmo trutta L.) and Atlantic salmon ( Salmo salar L.) from a lacustrine system in western Ireland

Abstract

A combination of electrofishing of feeder streams and shore seine netting of two lakes in a salmonid fishery in Burrishoole, western Ireland provided evidence of extensive use of lacustrine habitat by juvenile Atlantic salmon and brown trout. Mean densities of 0.024 trout and 0.002 salmon m −2 were recorded in L. Bunaveela (46ha), and 0.010 trout m −2 and 0.010 salmon m −2 in L. Feeagh (410 ha). Appearance of 0 + salmon and trout in summer seine net catches indicated early downstream movement of fry from inlet streams to lake inshore areas which also provided nursery habitat for older age classes. Total trap records of salmon and sea trout smolts migrating from Burrishoole catchment since 1970 were used to provide one of the first published estimates of smolt production from a lacustrine catchment in temperate Europe. Trout and salmon smolt output from Burrishoole was shown to have declined by about 50% since records began. Current levels of production are estimated at about 4 sea trout smolts ha −1 (0.4kg ha −1) and about 13 salmon smolts ha −1 (0.3 kg ha −1).