Preliminary observations on the induction of triploidy in Abramis brama by cold shock

Cold shock (2 degrees C) lasting for 45 or 60 min was applied to eggs from bream (Abramis brama), beginning at 2, 3, 4, 5, 6, 7 and 8 min after fertilization. The lowest survival rate was observed in those groups treated in which a cold shock started at 4 or 5 min after fertilization. Groups exposed to cold shock lasting for 60 min showed a higher percentage of triploids than in groups shocked for 45 min. The highest yield of triploid embryos was produced by the cold shock which started 8 min after egg fertilization and which lasted for 45 min.