Reproductive efficiency of Austropotamobius pallipes complex in experimental rearing centers, in relation to some individual measurements, to their original watercourses and to the reproduction year

Our research aimed to collect data about fertility of Austropotamobius pallipes in order to evaluate its reproduction effi ciency. From 2008 to 2012 two rearing centers formed by outdoor pools were used as experimental farms and young crayfi shes produced were used for reintroduction according to LIFE project CRAINat (LIFE08NAT/ IT/000352). Between September and October we caught 407 reproductive females (activated glair glands). They originated from 17 watercourses of the Lombardy pre-alpine zone. We have measured all the animals as concerns total length (from the tip of the rostrum to the end of telson; average 77.07±8.38 mm) and weight (average 13.15±4.26 g). They were individually marked. The whole rearing cycle (mating, egg-bearing, hatching of juveniles) was conducted in semi-natural conditions in the outdoor pools. In all the months of May we checked the egg-berried females. In the fi ve years period we have obtained 40.8% of berried females. We tested if reproductive effi ciency varied between females, rearing centers, the original watercourses and the rearing years. To do this, we used a GLMM (generalized linear mixed model) with binomial error in which the present or absent of egg-berried was the response variable, the total length and the original watercourses were the fi xed component, while the rearing years are the random one. The rearing year was the only variable signifi cantly affecting the reproductive effi ciency of females (LR-χ² = 6.543, df = 1, P = 0.010; σ² = 0.23±0.48), since the probability to produce fertile eggs resulted higher in 2008 and 2011 while the lowest occurred in 2009