Evaluation of the influence of light conditions on crayfish welfare in intensive aquaculture

During the last years, evidence has arisen for the ability of crustaceans to suffer from stress and noxious situations. This has led to an increasing public concern for crustacean welfare. Due to the interest in intensification of crayfish aquaculture, the question arises whether artificial culture conditions may impact these crustaceans’ welfare. We evaluated the effect of six light conditions on noble crayfish (Astacus astacus) behaviour in a recirculating aquaculture system. Crayfish were cultured under cool (5,500 K), neutral (3,800 K) or warm (2,600 K) white light, using bright (761 lux) and weak (38 lux) intensity. The crayfish’s dark-light preferences were evaluated by observing their behaviour in a plus maze. Animals kept under 38 lux spent 27.94±8.95% of their time in the light arms of the maze, while those kept under 761 lux only spent 20.06±9.98% in the light arms. Thus, crayfish from bright light showed a slight trend to avoid the light arms of the maze (P=0.098), an indication of anxious behaviour. The light spectrum had no influence. Following earlier preliminary signs of pain perception and neophobia in A. astacus these new observations invite to investigate further indications of a more intensive mental life in crustaceans. Human activities such as the catching, rearing, shipping and cooking of crustaceans may have a considerable impact on the welfare of these animals if these results are confirmed. We argue there are good ethical reasons to re-evaluate the omission of non-cephalopod invertebrates from European animal welfare legislation.No ISSNstatus: publishe