Survival of Early Stripped Eggs of the Noble Crayfish, Astacus astacus, and Effects of Saline Solution During Artificial Incubation
There is growing interest in using recirculating aquaculture systems (RAS) to produce juvenile noble crayfish, Astacus astacus (Linnaeus), a valuable and once plentiful food species in Europe, now a highly endangered species. The survival rates of early stripped eggs of A. astacus were compared across anti-fungal treatments in an artificial RAS incubation system based on a saline bath of approx. 20 – 22 mS cm-1 or 15 – 16 PSU over two different durations. Time from fertilisation to hatching was 54 days or 1220 degree-days. Low survival rates (live successfully hatched juveniles at end of experimental period) between 13.9 ± 2.5% and 25.4 ± 1.5% were obtained. Survival was significantly affected by the duration of egg bath within the saline solution with twice as high survival rates when eggs were saline-bathed once every two days for five minutes in comparison to eggs without treatment. Fungal rates were significantly affected by treating the eggs with a saline solution with infection rates decreasing from 3.7 ± 1.0% to 0.8 ± 0.5% in the ten minute saline bath treatment. Appropriately applied saline bathing can markedly improve survival of early-stripped noble crayfish eggs. However, further research is required to determine whether viable levels of hatching success can be obtained using early stripping and saline treatment.
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