Salmo Trutta.
Species description.
Salmo Trutta, brown trout or Atlantic trout is the most well-known native trout of Europe. It has three different life forms which are genetically the same. A form that lives their live in rivers Salmo Trutta morph Fario, a lake form Salmo Trutta morph Lacustris, and an anadromous form Salmo Trutta morph Trutta also known as sea trout. Sea trout can grow up to 120cm and 20kg and are the largest of the three forms, lake trout can reach about the same size and weight but the river form stays smaller with a maximum around 90cm and 10kg.
Behaviour.
When brown trout hatch, they feed in the stream for 1 to 3 years before some of them smolt this means they get ready for life at sea. if or when a fish smolts depends on genetics and environmental factors. After 5 years at sea hunting for fish and crustaceans, they swim up freshwater to reproduce. Unlike salmon they won’t always return to their birthing grounds and they reproduce multiple times. Reproduction occurs with sea trout and resident fish mixed. For fish that stay in fresh water they start their life eating aquatic insects, larva and other small insects. When they reach about 50cm they start to include fish as prey and larger fish even eat mice.
History.
Salmo Trutta is one of the first species to spread throughout Europe during the Pleistocene this happened with 5 different lineages the Atlantic, Danubian, Adriatic, Mediterranean and Duero. These lineages are the evolutionary parents of a lot of species found in Europe. Especially in the Mediterranean a lot of species evolved with in the brown trout complex. The Danubian lineage was known under the name Salmo Labrax until a study in 2018 concluded that this was biologically the same species with just enough difference to see it as a local variant. Throughout history brown trout have been stocked in a lot of water outside its native range like America and New Zealand. But also, different lineages have been stocked outside its native range like Danubian and Atlantic lineages being stocked in in the range of the Adriatic and Mediterranean lineages. Where it is a threat for hybridising with other species in the brown trout complex.
Threats.
Salmo Trutta is one of the widest spread species and has the status least concern. Even though it is still on the brink of extinction in some of its native habitat for example in the Netherlands. Damming and canals and lakes make it hard for smolts to reach the sea and populations are small even with the help of stocking. Rising water temperature and pollution and overfishing are other threats the species faces. And separate lineages mixing is a threat for unique populations.
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Distribution.
Within Europe the Salmo Trutta is found in every country but even though the different lineages combined once spread across the whole of Europe only the Danubian and Atlantic lineage are still considered Salmo Trutta. The other lineages evolved into new species and thus their habitat is no longer seen as native to Salmo Trutta. Countries where Salmo Trutta are native are: Iceland, Norway Sweden, Finland, Ireland, Scotland, England, Wales, North-Ireland, Denmark, Estonia, Latvia, Lithuania, The Netherlands, Germany, Poland, Belgium, France, Czech Republic, Slovakia, Switzerland, Austria, Hungary, Romania, Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro, Kosovo, Bulgaria, Spain, Portugal. North Macedonia and Italy both have a very small region which belong to the Danube basin and Italy has a very small part belonging to the Rhine basin. This means that Salmo Trutta is native their but only in a very small part of the country.
Impresion photo's from contenders
