The artificial incubation of crayfish eggs: review and report from an experimental study concerning the effects of offspring origin (maternal or artificial incubation) on the survival and growth of juvenile signal crayfish (Pacifastacus leniusculus, Astacidae)

Abstract

The development of artificial incubation techniques in astacid crayfish has attracted attention from scientists in many countries ever since the nineteenth century. It is only in the last few years that these techniques, along with studies on egg storage and transport, have provided reliable options for improving the reproductive phase in farming. The juveniles produced need to be reared until they reach a sufficient size both for restocking and for growing purposes. In view of the current level of knowledge of rearing juvenile astacids, two 80-day experiments were carried out under controlled conditions to compare the survival and growth of Stage 2 juvenile signal crayfish (Pacifastacus leniusculus) from two origins: maternal or artificial incubation. In the first experiment, three treatments were tested: juveniles from artificially incubated eggs with formaldehyde treatments, juveniles from maternal incubation and a mixture from both origins (50% each). Survival rates ranged from 87.8% to 93.3% with no significant differences among treatments. Crayfish from artificial incubation grew significantly faster (11.47 mm carapace length (CL), 373.80 mg weight) than crayfish from maternal incubation. In the second experiment, a bifactorial design included four treatments: the crayfish was derived from artificial or from maternal incubation and was fed once a day or twice a day. Final survival rates ranged from 68.89% to 77.78%, with no significant differences among treatments. Crayfish from artificial incubation grew significantly faster than crayfish from maternal incubation. The highest CL (14.54 mm) and weight (780.13 mg) were reached by the juveniles from artificial incubation that were fed once a day. No significant differences were found between the two feeding frequencies. Results showed that artificial incubation with formaldehyde treatments had no harmful effects and made it feasible to get a better performance from the juveniles obtained.

Muddied waters: suspended sediment impacts on gill structure and aerobic scope in an endangered native and an invasive freshwater crayfish

“…Survival in the study did not reflect SS treatment for either species, however, there was mortality in all treatments and the control, particularly for A. pallipes, inferring that a factor other than SS was responsible for the lower overall survivorship in this study than would be expected for crayfish maintained in aquarium facilities (Sáez-Royuela et al, 2002;Gonzalez et al, 2009). One explanation for this may be that the bubble stream within the experimental chambers impaired successful moulting as several crayfish were found dead during their moult, which for the juvenile life-stage used in this study, occurs 4-6 times per year (Pratten, 1980).…”

Effects of different bronopol treatments on final survival rates in the artificial incubation of crayfish eggs (Pacifastacus leniusculus, Astacidae)

“…Recent knowledge on artificial incubation techniques for crayfish eggs, along with studies on egg storage and transport, provides reliable options to intensify the reproductive phase of astacid culture (see review by González, Celada, García, González, Carral & Sáez-Royuela 2009).…”

The use of formaldehyde for the disinfection of maternally incubated eggs of noble crayfish (Astacus astacus)

“…It is clear that in Italy and in other European countries where crayfish farming is not very well developed and maternal incubation is still used, an environmental friendly method for disinfection could improve this sector. The introduction of artificial incubation is advisable for the future of crayfish farming in Italy, as highlighted by the Spanish experience (Celada et al 2004;González et al 2009). Finally, no apparently negative effect of the disinfection method was observed on the female crayfish, and considering that a formaldehyde concentration of 500 mg l -1 was found to be effective, this concentration can be recommended for future utilization in crayfish farming.…”