Marble Trout

Names in dialect: marmorata, truta vecia, miaga, truta nostrana.

Marble trout present a distinctive grey, brown or green marble pattern on the back and sides, which extends to the gill cover but not to the fins. They have a slender, cylindrical-shaped body, large head, extremely large mouth with the jaw extending beyond the rear edge of the eye and strong teeth. The dorsal and caudal fins are dark grey; the pectoral, ventral and anal fins are light grey or yellowish. In their juvenile stage they can have small red spots on their body, like young brown trout. Their total length can exceed one metre and their body weight 15 kg.
Their favourite habitat is the medium to upper reaches of larger rivers, which provide plenty of refuge and deep potholes, downstream from brown trout areas. They are often found together with grayling, bullhead, rheophilic cyprinids (barbel, chub, dace), and also brown trout. They can move into lakes where they take on the colours, to a greater or lesser degree, of lake trout, known as trota miaga.
Young marble trout feed on insects and crustaceans that they find on the river and lakebeds. As they get bigger they start to prey on fish, mainly bullhead, minnows, brook barbel and even small trout.
The males reach sexual maturity in their 2nd or 3rd year and the females a year later. They swim up the rivers and tributaries to spawn on gravel beds with shallow waters (10-40 cm), usually at the bottom of potholes. Spawning takes place between November and December, in the same way as for brown trout, with which they can hybridise.
Endemic in the Padano-Veneto area up until forty years ago, marble trout was the typical trout species in the watercourses on the south side of the Alps, including those in Trentino. Today it has become rare almost everywhere and has disappeared from many areas due to the water being used to produce hydroelectric power, artificial river beds being built and the frequent repopulating of waters with trout “ready to be fished” purchased from fish farms, which reduce rivers to receptacles for farmed fish. It has been seen that when the introduction of fish is suspended in areas favourable to marble trout, these return spontaneously. A serious danger is posed by genetic pollution, caused by using farmed fish stocks to repopulate free waters.
Marble trout are an excellent food fish, highly prized by amateur fishermen. The main fishermen’s associations endeavour to support native marble trout populations by means of artificial fecundation in hatcheries down in the valleys.