Morphological and biochemico-genetic analysis of the silver carp [Hypophthalmichthys molitrix] and big head [Aristichthys nobilis] and their hybrids reared in Czechoslovakia
1990
Slechtova, V. | Valenta, M. | Do Doan, H. | Slechta, V. (Ceskoslovenska Akademie Ved, Libechov (CSFR). Ustav Fyziologie a Genetiky Hospodarskych Zvirat)
Six groups of fish from different localities and including more than seven hundred silver carps, big heads and hybrids, were subjected to morphological and biochemico-genetic analysis. It has been shown that besides the pure species of silver carp (Tb) and big head (Tp), Czechoslovak waters are also inhabited by hybrids (H) of both species (Tb x Tp or Tp x Tb) and mainly by hybrids of the F2 and subsequent generations, especially the H x H, Tp x H or H x Tp. It was demonstrated on the basis of the species-specific biochemical markers (Pa, Al, s-MDH, NSD, My III, Ck and Est II) that it was comparatively very easy to distinguish the Tb from these hybrids and that the known morphological markers would suffice for that. On the other hand, morphological differentiation of the H from the Tp is difficult, requiring as many specific biochemico-genetic markers as possible for accurate identification. When only one species-specific biochemical markers was used, almost one-third of the mixture of fish characterized morphologically as H which, in turn, biochemically corresponded to Tp. With the use of six or more independent biochemical traits, all the fish morphologically characterized as H really had species-specific biochemical markers corresponding to H and two-thirds of the fish morphologically identified as Tp were in fact H. The brood Tb of the Pohorelice Fish Farm always had morphological and biochemico-genetic markers corresponding to Tb and in the brood Tp stock a small part of the fish exhibited differences between the two methods of identification used, suggesting that H was present. Hence, when new brood Tp are to be picked, their species purity should have been verified on the basis of specific biochemico-genetic markers.
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