Rhône Trout

Distinguished from all congeners in Europe by its unique body with 4 broad black bars, behind gill opening, under dorsal base, above anal fin origin and at posterior extremity of caudal peduncle ( bars clearly distinct in non-stressed individuals; some Balkan species may show similar bars, but only in very stressed situations; in other species only weakly marked when stressed). Differs further by the combination of the following characters: caudal fin truncate to slightly emarginate; usually lacking red spots on body; usually lacking red or orange dot on adipose; juveniles with 9-12 vertically elongated parr marks. The 4 bars are present in populations of Dourbie (upper Tarn system, France), which is distinguished by having red spots and dorsal, pelvic, and anal fins with white anterior margin. This represents possibly an introgression zone between Salmo rhodanensis and Salmo c.f. cettii (Ref. 59043).

Inhabits rivers and streams in clear, cold, well oxygenated water and with slow to fast current. Preys on invertebrates, fish and amphibians. Spawns in late December on gravel or coarse sand. Several populations represent a significant proportion of hybrids with Salmo truttaproduced in aquaculture and stocking. Attains a maximum size of up to about 80 cm SL (Ref. 59043).

Salmo rhodanensis, or the Rhône trout, is a salmonid fish, a putative species of trout resident in the Rhône river drainage in France and Switzerland. It was previously considered as belonging to Salmo trutta. Salmo rhodanensis is an exclusively freshwater fish, and is uniquely characterized by four broad black bars on its body: behind gill opening, under dorsal base, above anal fin origin, and at the base of the tail.

The species is currently threatened by hybridization with the actual Salmo trutta that has been introduced by stocking to the same drainage. Pure, non-introgressed populations of the Rhône trout are actually not known.