Sea Trout Sampling (Annual to 2026)

As part of AFT's monitoring of the health of migratory salmonids in the Argyll and the Isles region of Scotland's aquaculture zone, annual monitoring of sea trout and their parasite burdens are undertaken at several sites from May to July each year.

In 2025, AFT undertook a total of 96 surveys at 20 sites sampling 941 sea trout which include sites in Loch Linnhe, Loch Creran, Loch Etive, Loch Na Keal (Mull), Sound of Shuna, West Loch Tarbert, Loch Fyne, Kyles of Bute, Kilbrannan Sound, Isle of Arran and the Clyde estuary. The surveys were carried out using a seine net which is deployed from a motorboat.

Hauling the seine net back to shore in Loch Creran

Any sea trout caught are then measured for length, weighed and the number of the different life stages of any sea lice are counted and recorded before the fish are returned to the water. In 2026, AFT will also be PIT tagging some of the sampled trout to better understand the potential for recapture of individual fish.

Measuring the weight and length of a post-smolt sea trout

The information from different sampling sites is used to inform aquaculture companies and regulatory agency, SEPA about the health of wild fish. AFT are also collecting information on signs of lice grazing, predator damage and other disease present on the fish.

Some trout have sea lice and fin damage caused by grazing

Some of the data (and sea lice) collected by these surveys is also informing other projects such as the Scottish Association of Marine Science's Loch Etive Sea Lice Project. AFT will also be taking some genetic surveys as part of an academic study of sea trout populations on the west coast. We thank the volunteers that help us with some of the surveys.