Survival of Early Stripped Eggs of the Noble Crayfish, <i>Astacus astacu</i>, 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 82 days or 1191 degreedays. Low survival rates (live successfully hatched juveniles at end of experimental period) between 11.0 ± 9.5% and 26.6 ± 3.7% 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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