Rainbow Trout - A Biology

[Old Smoothound]

THE RAINBOW TROUT

By Old Smoothound

Description and Colour

The Rainbow Trout (Oncorhynchus mykiss) is the native trout of North America.
As its name suggests, the back is usually an Olive green, through to a roseate or violet band running the length of its flank to a paler underside. The colours deepen towards the winter spawning. The spots that freckle the back and flanks are smaller than those of the Brown Trout and lack the pale rings. Unlike the Brown’s, the rainbow’s spots are carried through to the tail fin.

Distribution

Oncorhynchus mykiss is a native of the brawling rivers of the west coast of America and of rivers of the Bering Strait in the north down to the Mexican rivers of the Gulf of California. Across the Bering Strait the same species runs the rivers of Russia as far as the south of China.

BIOLOGY

Rainbow Trout spawn in November and December through to the spring, the fry emerging to feed and grow faster than young brown’s. Diet will also affect colour. Where the trout’s diet is high in crustaceans containing the pigment carotene the trout will, in general, have a bright pink flesh. Rainbow trout are migratory in their natural habitat and run the turbulent rivers to get to the sea to feed and then return to their native rivers to spawn; these are named Steelheads, and are similar in behaviour to the Atlantic Salmon. The rainbow is a veracious feeder and will go off in search of food. The Rainbow has a life expectancy of around 6 years.

DIET

Now that we know where they are to be found how can we catch them? Well let's first take a quick look at what they eat'. As you might expect feeding intensity is closely related to water temperature - and feeding is at its lowest in February and March when water temperatures are at their lowest, and at a peak in the late spring and early summer - but it is generally high throughout most of the year. Rainbow Trout consume both a large variety and a large quantity of food organisms.

TROUT RISE FORMS

A straightforward rise: circles fan outwards when a trout takes a fly from the surface of the water, though the size length and shape will vary in different water types and conditions.
A trout sees a dry fly only from beneath, which is why it is a waste of time tying a pattern with elaborate wing detail on the upper side. However, the wet fly or nymph may be seen from any angle including above.


This is a piece from my course work for the title of S.T.A.N.I.C. Instructor as given by the Salmon and Trout Association after many months of hard work. This material is copyright of Old Smoothound and may not be re-produced without express permission by the copyright holder.

[Norfolkboy]

Lovely read

[Miles]

Thanks Smoothy, nice piece. Good point about the wing detail on a dry.

Is there any biological reason why a rainbow is more likely to chase a gaudy lure than a brown is ?

[Old Smoothound]

Rainbows tend to chase lures as they are more agressive in defending their patch so to speak. But at the right time of year, the Brown will chase a lure especially if they look similar to fry.

I used to fish Grafham Water for Big Browns, and woul only use lures, because these fish are canibal and carniverous by the time they get to 8lbs or more and they spend most of the time down deep waiting to ambush small fish.

[kiwimarty]

Thanks for another great read Shaun.

Kiwi.

[pingu]

totally agree with mart, excellant as usual mr smoothy

[eljeffo]

Very good but I'd be a little weary of that SATANIC instructor! j/k hehe! :P

[..::Pike Pirate::..]

nice post there, great informative read!

[Twiddler]

Great read, lots of good info there