Optimizing reproductive performance and embryonic development of red swamp crayfish Procambarus clarkii by manipulating water temperature

摘要

Aquaculture of red swamp crayfish, Procambarus clarkii (Girard, 1852), has developed rapidly worldwide in recent years with promising prospects. However, limited knowledge about temperature effects on reproductive performance and embryonic development has hindered the development of crayfish aquaculture. The two present studies were conducted to identify optimal water temperatures (17 degrees C, 21 degrees C, 25 degrees C, 29 degrees C and 33 degrees C) for reproductive performance (experiment 1) and embryonic development (experiment 2) of P. clarkii. Totally, there were 12 replicates, with 480 adults and embryos from 60 ovigerous crayfish selected for experiment 1 and 2, respectively. In the first experiment, the survival of adult crayfish was not significantly affected by the temperatures tested. However, significantly higher feeding rates, spawning rates, and fecundity were obtained at 21 degrees C and 25 degrees C when compared to those at 29 degrees C and 33 degrees C. Polynomial models and loess regression fitted to the experimental data showed that highest spawning rates and fecundity occurred at 21 degrees C while shortest duration from mating to spawning was found at 33 degrees C. In the second experiment, we found that optimal embryonic development was at 25 degrees C with shorter hatching time and no abnormalities observed. However, while embryos showed abnormalities and subsequently died at 29 degrees C and 33 degrees C. We further built a temperature-dependent developmental model for P. clarkii embryos: D (developmental time, days) = 3,140,837(T-2.03)(-3.76). Based on these results, the temperature range 21 degrees C - 25 degrees C was recommended for adult crayfish reproduction and 25 degrees C was recommended for embryonic development. This study indicates that manipulating water temperature is an effective alternative to current artificial reproduction techniques (e.g. eyestalk ablation and injection hormones) to induce spawning and embryonic development and thus provides mass production of juvenile P. clarkii for aquaculture.