Abstract
Three experiments assessed the effects of cold-shock induced triploidy on (1) the incidence of abnormal cell cleavage during embryogenesis, (2) hatching success and the proportion of live yolk-sac larvae in normally cleaved versus abnormally cleaved embryos, and (3) survival of triploid larvae of spotted sand bass (Paralabrax maculatofasciatus). All spawns were obtained by hormonal induction (LHRHa). Triploidy was induced by cold shock shortly after fertilization. In experiment 1, the percentage of abnormal cell cleavage was significantly higher (P < 0.05) in the cold-shocked group than in the control group, while the hatching rate and the proportion of live yolk-sac larvae were significantly lower (P < 0.05). In experiment 2, when normally and abnormally cleaved embryos from the control and cold-shocked groups were incubated separately, normal cleaved embryos in the cold-shocked group showed a significantly higher hatching rate and proportion of live yolk-sac larvae than abnormally cleaved embryos in the same group. No difference was observed in the control group. In experiment 3, a significant decrease (P < 0.05) in the triploidy count was observed throughout the larval period. Final survival was drastically lower for triploid larvae compared to cold-shocked diploids and untreated eggs. Low triploidy percentages at the end of the larval period would seriously hinder the development of triploid sand bass culture.
Highlights
The spotted sand bass, Paralabrax maculatofasciatus, is a potential species for aquaculture along the northwest coast of Mexico
Higher mortality related to abnormal cleavage in cold-shocked spotted sand bass embryos was observed
Abnormal cell cleavages were observed in the control and cold-shocked groups; while the rate of abnormal cleavage was 25% in the control group, hatching success exceeded 90%
Summary
The spotted sand bass, Paralabrax maculatofasciatus, is a potential species for aquaculture along the northwest coast of Mexico. Paralabrax maculatofasciatus, es una especie potencial para la acuicultura a lo largo de la costa noroccidental de México. Sexual maturation occurs precociously, before commercial size is reached (unpublished data). This is considered a major problem because sexual maturation is accompanied, in many species, by a decrease in survival and growth rate (Felip et al 2001, Piferrer et al 2009)
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