Effects of management on survival and growth of Stage 2 juvenile freshwater signal crayfish ( Pacifastacus leniusculus Dana) under laboratory conditions

Abstract

Four experiments were carried out in order to evaluate survival and growth rates of Stage 2 juvenile Pacifastacus leniusculus under different management conditions: effects of offspring origin (artificial incubation, maternal incubation under laboratory conditions and maternal incubation under natural conditions), of different shelter availability, of water circulation systems (partially re-circulated and full flow-through), and effects of certain flow rates. Juveniles kept singly, rather than in groups, had higher survival rates. However, when juveniles were in groups, they showed faster growth. Offspring from artificial incubation did not show significant differences in survival and growth rates from those from maternal incubation. The addition of pebbles as shelter did not improve survival rates. The use of a full flow-through system allowed significantly higher survival and growth rates. A flow rate of 1 l/min improved the survival rate in comparison with 6 l/min, but not growth. In general, the highest mortality occurred during the first 40–60 days of the experiments, although a great variation in the final results was observed.