§ Mr. OnslowTo ask the Secretary of State for Scotland what research his Department has commissioned into the decline of sea trout stocks in Scottish waters.
§ Mr. Michael ForsythStudies of sea trout by scientists from the DAFS freshwater fisheries laboratory at Pitlochry have concentrated on areas in the north-west of Scotland where catches of sea trout appear to have fallen sharply in 1989. Work so far has included detailed sampling of sea trout fisheries in Loch Hope, Loch Maree, Achiltibuie, Loch Shiel, Loch Morar, Loch Eilt and a group of lochs in Skye with analysis of the size, age, sex composition of the catches and, where possible, of mature fish in the spawning burns. Surveys of juvenile distribution and abundance, including the physical and chemical evaluation of habitats, have also been undertaken in burns flowing into Lochs Hope, Maree and Eilt.
The preliminary results of this work suggest that, as in the west of Ireland, growth and survival rates in fresh water are within the normal range. This points to lower survival rates at sea as the primary reason for the lower number of returning adult sea trout.
The reasons for apparently poorer marine survival are not yet clear. Sea trout at sea, or returning to estuaries, are now being sampled to evaluate their overall condition, diet and status in terms of disease and parasites. It is too early yet to draw any conclusions from this work or the other continuing studies in north-west Scotland.
326WDAFS scientists are also undertaking long-term studies of the dynamics of migratory trout populations in eastern Scotland and analysis of the sea trout catch statistics collected for Scotland as a whole.