Impact of dietary protein content on growth of the white-clawed crayfish Austropotamobius pallipes (Lereboullet, 1858) (Decapoda, Astacidae) in captive rearing for conservation

Abstract

The white-clawed crayfish, Austropotamobius pallipes is endangered throughout its entire biogeographic range in Europe due to infection with Aphanomyces astaci (crayfish plague) and habitat deterioration. Ex situ propagation is of increasing importance to safeguard genetic resources and enable restocking measures after the pathogen’s disappearance. This study aimed to quantify the impact of crude protein content on growth response and survival of white-clawed crayfish as optimal growth efficiency of white-clawed crayfish captive rearing has remained largely unexplored. Three separate 80 day feeding trials were conducted: juvenile monosex and juvenile mixed sex crayfish fed medium and high protein diets, and mixed sex adult crayfish fed low and high protein diets. Survival, weight gain and carapace length gain were measured bi-weekly during the trials. Growth response as the relative gain in cephalothorax length in juvenile mixed sex assemblages was significantly higher for the medium protein diet (Mdn = 19.4) than for the high protein diet (Mdn = 15.2, , ) with an average carapace length increase of 18.3% compared to 16.1% for the medium and high protein diet, respectively. However, there was no significant difference in the relative weight gain of juvenile mixed sex assemblages. All data for weight gain and carapace length gain for the juvenile monosex assemblages and adult mixed sex assemblages were not significant in response to diets. Thus, there was no obvious advantage of a high protein diet in the captive rearing of A. pallipes and in the case of the juvenile mixed sex assemblage the higher protein content can reduce growth in terms of size.