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Sea trout scale reading workshop

Posted: Friday 18 February, 2011 @ 16:25:59

Dr Andy Walker and Ben Rushbrooke examining a sea trout scale.

The life history of trout and salmon can often be interpreted via the examination under magnification of scales from respective fish. Scale reading provides information such as 'smolt age' (the number of years the fish spent in freshwater prior to migrating to sea), 'age at spawning', and growth rates.

Notable studies of sea trout from the River Ewe system, based on scale reading, include that of Nall (1926) and Walker (1980). Both these studies were based on examination of scale samples from over 1000 fish, including samples from sea trout of up to 10lb.

On 17th February 2011, WRFT held a sea trout scale reading workshop. Dr Andy Walker provided training and assisted with the reading of samples of sea trout scales collected as part of the WRFT sea trout sampling programme.

Samples of scales from the sweep netting sea trout sampling programme were compared with those from other sea trout and other 'trout' collected within Wester Ross in recent years. As an initial output from the workshop, an online trout scale catalogue is being developed. Please click here or visit the 'Sea Trout Scale Catalogue' on the downloads page to access examples.

Thank you to Dr Andy Walker for supporting this workshop. The workshop was funded by the Scottish Government via the Tripartite Working Group.


Nall, G.H. (1926) The Sea Trout of the River Ewe and Loch Maree. Fisheries Board for Scotland, Salmon Fisheries Report No. 1.

Walker, A.F. (1980) A Report on the Growth Rate, Size and Age Composition of Sea Trout Caught by Anglers Fishing Lochs Maree, Clair and Coulin in 1980. Freshwater Fisheries Laboratory report, Scottish Office