Limited holding space reduces growth and behavioural performance in juvenile European lobsters

Conservation aquaculture offers important tools to secure sustainable animal supplies for human use. However, intensive aquaculture practices are increasingly raising concerns about the welfare conditions of farmed animals, which typically face high mortality rates due to diseases, cannibalism, and aggression. Here we focus on the European lobster (Homarus gammarus), an economically and ecologically important decapod species that has been subjected to conservation programs for decades. While standard husbandry procedures typically result into large numbers of juvenile lobsters produced and released, it remains poorly known whether such standard settings alter the development of behavioural and life-history traits of ecological importance for the animals to survive in the wild. Here, we investigate whether the size of the individual holding spaces affects the behavioural traits (exploration, space use, and sheltering) and growth (carapace length, intermoult period, and percentage moult increment) of juvenile lobsters during their early benthic stages. Our results offer solid evidence that rearing lobsters into small holding spaces not only limits and slows down their overall growth, but also compromises the development of ecologically-relevant behaviours that are essentials for these animals to survive in a complex and risky environment. We point the attention toward the benefits of adopting better rearing procedures to improve the welfare conditions of hatchery-cultured lobsters that can, in turn, result into faster growth rates and the development of competent behavioural repertoires of these valuable organisms—likely to improve the effectiveness of conservation programs.