Induction of triploidy in spotted sand bass (Paralabrax maculatofasciatus Steindachner, 1868) by cold shock

Abstract

Conditions for the induction of triploidy with cold shock of fertilized eggs of the spotted sand bass Paralabrax maculatofasciatus (Steindachner) were investigated. Different temperatures (12, 8 and 4 °C), timing of cold shock application (5, 10 and 15min after fertilization) and duration of the shock (5,10,15 and 20min) were tested. Triploidy was determined using flow cytometry at 12 h after larvae hatched. Triploids were produced only when the cold shock treatment was applied 5 min after fertilization. No signifiant difference was observed in the percentage of triploidy betweentemperature and the shock duration. At 8 and 4 °C, 100% triploidy was obtained at different durations of cold shock. Survivalwas significantly lower at12 or 4 °C thanat 8 °C. No significant difference was observed for shock duration at the temperature of 8 or 12 °C; however, at 4 °C, survival was signi¢cantly lower at longer durations. We recommend induction of triploidy by applying cold shock at 8 °C for a duration of 15-20 min starting at 5 min after fertilization, in the spotted sand bass