The objective is to study different factors of variations in the body shape
of trout (Salmo trutta) belonging to the Mediterranean lineage (indigenous trout) or
Atlantic lineage (introduced trout), and their hybrids. Using
thin plate-spline (TPS) method by pointing landmarks, it made possible to
provide a graphical representation of the characteristic conformation of the
individuals. The characteristics of form highlighted let appear – that the
male trout have a dorsal part more prominent than that of the female trout
and a larger head – the existence of a general curvature of the body related
to the size of trout, independently of the sex. In addition, characteristics
of form provide satisfactory results to distinguish the Mediterranean
lineage from the Atlantic lineage. The recognition of hybrid trout is more
random because very near to Mediterranean trout. The existence of a sexual
dimorphism could be established in spite of the absence of information on
the sex. Comparative with the sexual dimorphisms in spawning period reveals
morphological transformations during the reproduction, mainly for the males.
Independently of the genotypic and sexual dimorphisms, a general curvature
of the body related to the size was detected.