Scientists Probe "Mysterious" Trout's Behaviour –

Scientists Probe “Mysterious” Trout’s Behaviour Fish Farming Today Published:  21 July, 2003

TAGGING studies by scientists from Fisheries Research Services (FRS) on ferox trout have provided the first insight into the behaviour of this mysterious fish, laying the preliminary foundations for the development of a possible conservation strategy.

Ferox trout (Salmo trutta) are the top fish predators in many of the large, deep Scottish lochs feeding principally on smaller trout and Arctic charr (Salvelinus alpinus). Although once considered a separate species, the Scottish populations of ferox trout are in fact brown trout that have switched from a diet consisting of mainly invertebrates, to one almost exclusively of fish.

This change of diet to fish – the trigger for which is still unknown –not only boosts growth (the current UK rod record weight is 14.4kg), but also adds to longevity, with the oldest confirmed UK ferox being 23 years old. The large size of ferox trout means that they may have an important role in the population dynamics of trout, given that large female fish could not only have the advantage of spawning many more times than the smaller, shorter lived brown trout, but potentially lay more, larger eggs which could result in better survival.

Over the last few years, scientists from FRS have investigated the spatial and diurnal movements of ferox trout in Loch Garry (Perthshire) using radio and acoustic tags. Although the number of fish examined was small, they do provide an initial indication of behaviour.