In our study, the general trend for GSI in hybrids was to be intermediate
between common carp and gibel carp. In spring, the gonads of
common carp and gibel carpwere highly different, suggesting some differences
in reproduction aspects. Generally, the reproduction times of
both species overlap. However, there are two aspects that could explain
the observed pattern of GSI and the presence of F1 hybridswith amaternal
origin in gibel carp. In spring, even though the males of both gibel