During the monthly post-smolt tagging in the Laxford and Polla estuaries it was noted that the growth rates in the two areas were significantly different. Speculation as to the reason for this led to the development of a project to look at the prey availability within the two estuaries, and to try and establish any differences in the fish and invertebrate populations of the two sea lochs.
Three sites per sea loch were selected for monthly trawling, starting in May 2005, and the catch analysed. The abundance of invertebrates is recorded, while the fish are measured in more detail, giving length, weight, age (where possible) and stomach contents determined. This will help to build a picture of the populations in the two lochs and hopefully allow a comparison of the available prey within the two lochs.
Boats have been provided by Loch Duart Ltd (Laxford) and Rispond Estate (Eriboll), while the trawl was kindly donated by the Fisheries Research Services. Additional funding has been provided by Highlands & Islands Enterprise, for the first year of the project. Without all of this assistance, the project could not proceed.
Bringing in the trawl, Laxford (M. McFadden)
In addition to the trawling surveys, staff from the neighbouring fish farms are recording the species observed from the cages. By noting the plankton, jellyfish, fish, birds and cetaceans seen on a weekly basis, together with notes on the weather conditions for the week, we can build up a picture of the productivity of the lochs.
This is similar to the surveys being undertaken by Wester Ross Salmon, Loch Broom, and will allow a comparison over a larger part of Scotland.