Induction of Triploidy in White Crappie by Temperature Shock

Abstract

Abstract During two spawning seasons, triploidy was induced in white crappie Pomoxis annularis by temperature shock 5 min after artificial fertilization. Heat shocks of 36–40°C for 1–5 min resulted in 0–10% triploidy. Cold shocks of 5°C for 45 min and 60 min yielded 0–24% and 72–92% triploidy, respectively. Triploids were identified initially by chromosome counts in 1987, but examination of confirmed diploids and triploids indicated that they could be distinguished unambiguously on the basis of measurements of erythrocyte nuclear major axis. Erythrocyte nuclear minor axis and volume were substantially less reliable for identifying triploids. Flow cytometry was used to identify triploids in 1988. Limited data on juvenile fish revealed no significant size difference between diploids and triploids in most of the treatment groups.