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Brown trout and sea trout (Salmo trutta)

Trout spawn in small streams that flow into Loch Maree in October or November. During their first two or three years after hatching, all trout look much the same. However, after 3 or 4 years in freshwater, some trout turn silver and go to sea, leaving their siblings to remain as brown trout within the loch. 'Finnock' (small sea trout) return to freshwater after a few months of feeding in coastal waters. Larger sea trout may return to spawn several times during their lives - formerly reaching 80 cm or more in length. The Loch Maree sea trout population collapsed at the end of the 1980s and has yet to recover. Sea trout were affected by sea lice epizootics in Loch Ewe, most recently in 2001, 2003 and 2007. Sea trout populations elsewhere in the WRFT area have also been affected by sea lice and other factors.

There are several forms of brown trout in Loch Maree including ferox. Ferox are large brown trout that eat other fish especially charr. Ferox are much like other trout when they are small, feeding mainly on insects around the shores of the loch. However, when they reach about 30 cm in length and 5 years old, their diet is almost entirely of charr and small trout. By age 10 years, ferox may be over 60cm long. There are also numerous isolated wild brown trout populations in Wester Ross in streams and hill lochs above waterfalls that are inaccessible to sea trout and salmon.

A Fionn Loch trout         [Close]
Finnock and sea lice         [Close]
Gairloch hill loch trout         [Close]
Gairloch hill loch separated from Loch Maree (behind) by waterfalls         [Close]
Garbhaig falls trout (Steve Kett)         [Close]

Trout Gallery

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  • Dang, Vu H. (2013) Preliminary investigation of Aquatic Macro-Invertebrate Biodiversity in the Gairloch Hill Lochs, Wester-Ross Shire
    This thesis by Middlesex University student Vu Dang investigates the aquatic macro-invertebrates biodiversity of lochs at varying altitudes, located in the Gairloch district, Wester Ross Shire, Scotland.  Posted: 13/12/2013 (2.35MB)
  • Estuarine trout, Kerry Bay 7 June 2010
    This trout, the largest taken in the sea by the WRFT sea lice monitoring team, was taken in the sweep net; and the file shows photographs of scales from which the age has been assessed.  Posted: 07/06/2010 (508KB)
  • Ferox trout 700m Loch Maree 25 October 2011
    This is one of the largest trout recorded in the River Ewe - Loch Maree systems in the past 10 years. It was temporarily removed from a spawning stream. Scale reading suggests it is a 'ferox' trout with growth rate that increased when aged 7 or 8 as its diet changed.  Posted: 10/11/2011 (425KB)
  • Loch Torridon Sea trout report 2015
    This report presents some of the results of investigations to gather information about sea trout around the Loch Torridon area in 2015 following reports of exceptionally high concentrations of parasitic sea lice (Lepeophtheirus salmonis) on salmon farms within the area during the first six months of 2015 . Sea trout were sampled by Wester Ross Fisheries Trust during the period May-July 2015 using sweep netting, rod and line and electro-fishing. In October and early November 2015 a fyke net trap was operated in a tributary of the River Torridon to learn more about the spawning population of trout within that river system.  Posted: 05/01/2016 (7.75MB)
  • Mamo, Sara (2013) Trophic Status and Ontogeny: An Analysis of Brown Trout (Salmo trutta, L.1758) Growth and Diet in Wester Ross, Scotland
    This thesis by Middlesex University student Sara Mamo investigates the diet and growth of brown trout in Loch Coire na h-Airigh and Loch Feur, Wester Ross.  Posted: 13/12/2013 (1.17MB)
  • Problems for Sea trout in Wester Ross
    This presentation has been tidied up from one given at the sea trout and sea lice management workshop at Aultbea Village hall on 20th February 2014. Data for sea lice and other factors affecting sea trout in Wester Ross are summarised. The presentation concludes with an outline for a Scottish Sea Trout Project aimed at improving our understanding of how different factors affect sea trout in different parts of Scotland.  Posted: 21/02/2014 (6.57MB)
  • Recaptured male Gairloch sea trout 2012
    This wild sea trout, named 'Squaretail', has been caught 5 times in Loch Gairloch by the WRFT sweep netting team, providing further useful information about growth and migration of sea trout within the coastal waters of Wester Ross.  Posted: 28/09/2012 (972KB)
  • The Wild Trout of a Coastal Stream System in Wester Ross
    Poster showing some of the wild trout and their prey and predators found in a coastal stream system in Wester Ross.  Posted: 24/05/2011 (1.05MB)
  • Wester Ross Sea Trout Scale Catalogue April 2011
    The document provides links to photographs of sea trout and their scales from the sea and river estuaries of Wester Ross. The catalogue will be updated in response to comments received.  Posted: 05/04/2011 (989KB)
  • WRFT Sea trout Monitoring review 2012
    This report presents the results of sea trout and sea lice monitoring in 2012 within the WRFT area, and considers the occurrence of larger sea trout in Wester Ross and other parts of the West of Scotland.  Posted: 12/04/2013 (6.05MB)
  • WRFT Wild Trout Project Report 2006-07
    Posted: 24/06/2008 (1.24MB)