Morphometric characteristics as an indicator of the breeding process in carp

The study of the variability of exterior indicators in two-year-olds of three different strains of carp: the natural population of the Volga carp, the breed group of the Zagorsky carp and the butterfly carp breed. The research was carried out on the basis of the pond base of the experimental breeding farm of the VNIIPRH. It is shown that the introduction of the index of the relative size of the head to the total body surface into the analysis of a new breeding trait determines the significant discrepancy between the groups of the Volga carp and carp in the complex of morphotype features. It was found that the Volga carp is the most distant from the butterfly carp (the distance of the Mahalanobis is 13.18), as well as from the breed group of the Zagorsky carp (8,66). The breed groups of carp are located closer to each other (4.18). The greatest contribution to the separation of the studied groups of cyprinid fish is made by 7 morphotype features — body length, indices of pectoventral and antedorsal distance, length of snout, tail and dorsal fin, the ratio of head area to body area of fish. The relative head sizes of the carp breed groups are significantly higher than those of the Volga carp, which has not been selected in fish aquaculture. Thus, the head size of the Volga carp occupies 15.06%, and that of the carp after 7 generations of breeding — 15.93–16.82%. The Volga carp is characterized by higher values of body length and low values of relative head size, high back, fatness coefficient and body girth. It is shown that the relative size of the head can serve as an indicator of the difference in the breed groups of carp. An increase in the ratio of the head area to the surface of the entire fish is observed in the series: Volga carp — Zagorsky carp — butterfly. It is proposed to use this indicator as an additional characteristic of the breeding process and domestication of cyprinid fish.