How the selective breeding in aquaculture programs can change the body shape of cyprinids; a case study on the native Cyprinus carpio and a cultured stock

Decades since restocking program of the vulnerable native Cyprinus carpio in the southern Caspian Sea, the cultured stocks in hatcheries have created new challenge to protect the native population. Releasing the cultured common carp in natural water-bodies caused an uncertainty about originality of the carp broodstocks within the restocking program. To clarify that how the selective breeding with aquaculture purpose could change the body shape with aiming to prepare an identification key for the indigenous and cultured stocks, a landmark based morphological characteristics of these stocks from the Anzali Wetland and a hatchery were analyzed. Univariate analysis of variance of 100 adult specimens collected during the non-reproductive season were observed in 62 morphometric characters out of 78 (P<0.05). Principle component analyze (PCA) of morphometric characteristic showed a high differentiation between these stocks. In morphometric traits, linear discriminate function analysis (DFA), the overall assignments of individuals into their original groups between stocks were 100%. The PCA and DFA showed a morphological segregation of the studied stocks based on the characters head shape, pre-dorsal, pre-pelvic and pre-anal distances, caudal peduncle depth, dorsal fin and ventral fin origins, body depth and caudal fin origin. The results showed stocks represent two distinct morphological forms of C. carpio that had high morphometric differentiation. The results can be useful as baseline information on the native stock for conservational policy. To protect the vulnerable population, using wild native broodstocks in the restocking program is strongly recommended.