There have been several studies undertaken to monitor sea lice, in addition to the post-smolt sampling. These were carried out in conjunction with different groups and add to the information from sea trout surveys.
Undertaken in conjunction with the Association of West Coast Fisheries Trusts, this project ran for 6 years. Up to 30 sea trout are collected from estuaries throughout the west coast and the Islands during June and examined for sea lice. Within the WSFT area the Rivers Hope, Laxford and Inver were surveyed.
The results for 1997 - 2000 have been produced in a report and also published in a scientific journal:
Butler, J.R.A., Marshall, S., Watt, J., Kettlewhite, A., Bull, C., Bilsby, M., Bilsby, H., Ribbens, J., Sinclair, C., Stoddart, R., & Crompton, D. (2001). Patterns of sea lice infestations on Scottish west coast sea trout: survey results, 1997 - 2000. Copies available from the Biologist
Butler, J.R.A. (2002). Wild salmonids and sea louse infestations on the west coast of Scotland: sources of infection and implications for the management of marine salmon farms. Pest Management Science 58: 595 - 608.
This showed:
Sites on the periphery of the salmon farming zone had generally low infestations and an absence of prematurely returning fish.
Heavy settlements of chalimus caused tissue damage to dorsal fins.
Inter-year variations in infestations were related to salmon farm production cycles in the local hydrographic area.
In areas of single year class production, lice abundance fluctuated from low, background, levels in the first spring of production to high levels in the second spring.
In areas of mixed production lice levels showed fluctuations generally above background levels.
Undertaken as a joint AWCFT/Fisheries Research Service project, this project ran from 2002. It follows the a small scale study during 2001 by FRS at their Sheildaig Centre, Wester Ross, and involves taking plankton samples from a 50 m stretch near the shore each week at high tide. The project ran from March to August, with the samples being examined by FRS staff at Sheildaig.
Laxford Bay was included from the WSFT area, with samples taken from the same area as the sea trout samples. While the survey was undertaken for 2 years throughout Scotland, as a result of the unique operating pattern of Loch Duart Ltd, this was extended for a further year in the Laxford. To view the report on the Laxford, click here.
This was an MSc project, carried out in conjunction with Heriot-Watt University and undertaken by Tim Wilkinson. Inshore samples are taken from 5 sites within Laxford Bay and analysed for lice. A sample has also been taken from the area of the neighbouring fish farm for comparison and from a range of sites in Laxford Bay and Loch Laxford.
Thanks must be given to Reay Forest Estate, in particular Ian Morrison, for taking us out in the boat to get samples.