Four natural cyprinid hybrids recorded from Lake Vansjø, SE Norway
1981
Per Pethon
An examination of a sub-sample of 356 cyprinid specimens collected in Lake Vansjø, SE Norway in June, Aug. and Oct. 1978 revealed 187 specimens of Abramis brama (L.) and 94 specimens of Blicca bjoerkna (L.) together with four natural cyprinid hybrids, i.e. Abramis brama (L.) x Blicca bjoerkna (L.) (n = 67), Rutilus rutilus (L.) x Abramis brama (L.) (n = 3), Rutilus rutilus (L.) x Blicca bjoerkna (L.) (n = 1), and Blicca bjoerkna (L.) x Scardinius erythropthalmus (L.) (n = 4). The identification of the Abramis x Blicca hybrid required a five character complex, i.e. rays in anal fin, lateral line scales, pharyngeal teeth, operculum shape, and age/growth pattern, while the other hybrids agreed with previous descriptions. All four hybrids show intermediacy of their parentals, but the range of variation in the Abramis x Blicca hybrid characters indicates involvement of more than just the F1 generation and thus suggests hybrid fertility. It is concluded that the cause of hybridization is due to overlap in spawning time in mutually shared spawning areas.
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