Brown Trout Diversity
Trout are to be found worldwide. The two species of most interest to the fly fisherman are rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta). These have the same ancestors but divided into two separate groups around 15 million years ago, Oncorhynchus becoming isolated in the North Pacific and Salmo in the North Atlantic. Rainbow trout and brown trout cannot interbreed in the wild. Brown trout are one of the most genetically diverse species, with many varieties identified, resulting in much debate about their genetic classification as separate species or sub-species.
Many brown trout types appear to exhibit distinct characteristics, in appearance, behaviour or location, which has led to attempts over the years to assign them to separate species. These include Loch Leven Trout, Gillaroo Trout, Sonaghen Trout, Lake Trout, Ferox Trout, Slob Trout, Bull Trout and Sea Trout. We now recognise these as various strains of one and the same genetic species of brown trout, which are capable of interbreeding.
Brown Trout Distribution
The native range of Brown Trout extends from Iceland in the north to the Atlas mountains in Africa and from Ireland in the west to the Ural mountains and Caspian sea. Brown trout are not native to North America or to the countries of the Southern Hemisphere, but, from the late nineteenth century, brown trout have been transported and introduced wordwide and are now found in every continent except the Arctic and Antarctica. They have become naturalised in countries including USA, Canada, Australia, New Zealand, India, Sri Lanka, Bhutan, South Africa, Kenya, Zimbabwe, Malawi, Chile, Argentina and the Falkland Islands.
The worldwide distribution by man of brown trout is due to its well known sporting qualities, often introduced through the 1800s into British colonial territories, such as India, Australia and New Zealand. Similarly, in more recent years, rainbow trout have been introduced from North America into Britain and other European countries for the same reason and are now bred here and stocked into club or commercial fisheries throughout the country, providing sport for anglers, particularly in areas of high population density which may not give easy access to wild trout fishing in the remoter parts of the country.
