00000International audienceAbalone growth rate is often identified among important traits to improve through selective breeding. However, the rapid success of some selective breeding plans has sometimes led to negative effects in some aquaculture species due to trade-offs. One of them is the loss of homeostasis of selected animals which results in the inability to resist the stress experienced during the rearing process. In this context, this study aimed to analyze the phenotypic relationships between growth, and physiological and behavioural traits in Haliotis tuberculata under stressful conditions. Eleven traits related to growth, immunity, reproduction and behaviour were recorded under laboratory conditions. A total of 120 adults from wild or farm origin were first monitored during a 3-week stress period (high density and acute stress handling) during winter, followed by 6 months on-growing in sea-cages. Relationships between parameters were analyzed using a multi-factorial approach. Wild and farm stocks could only be discriminated on behaviour traits, confirming that the French abalone industry is in the beginning of the domestication process. After 3 weeks of chronic stress, the righting latency of an abalone was linked to better survival and faster growth. Abalones having the best growth after 6 months were characterized by higher activity during the previous winter period, whereas an early gonad maturation reduced the growth in summer. Our results provide a basis for the establishment of a multi-trait breeding program to improve the growth rate while controlling the evolution of physiological and behavioural traits.ăStatement of relevanceăThe relationships of behavioural and physiological variables with survival and weight gain after application of important stressors were studied in order to provide a better understanding of Haliotis tuberculata biology during early domestication stage. This paper will give information on new targets and tools for selective breeding

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Studies of the diet of abalone and other herbivorous gastropods, based on gut contents, may be biased against some species of algae, especially those that are most preferred. The blacklip abalone Haliotis rubra was fed for short periods on monospecific diets of eight algae, including red, brown and green species that span the range of preference. In addition, two preferred species were fed to abalone after one month's, one week's, or no starvation. The number of recognizable fragments of each alga per unit volume of crop contents was examined. Although key characters of some species remained recognizable even at an advanced stage of digestion, other algae were intrinsically less recognizable. Preferred red algae disappeared rapidly after one week's or no starvation but more slowly after one month's starvation. Less preferred algae were not eaten without a long starvation period and became unrecognizable relatively slowly, especially the least preferred brown algae Ecklonia radiata and Phyllospora comosa, which have high polyphenol contents. Thus, the gut contents of starved abalone in the field contain recognizable fragments of less preferred species for long periods, whereas well-fed abalone retain recognizable fragments of preferred species only for short periods.

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Domestication of Haliotis tuberculata has only recently begun. During the process, we expect that behavioural and physiological traits may evolve to become more adapted to their captive environment. These modifications may result from intentional selection of production traits or unconscious and unintentional selection due to conditions experienced in the farm environment. To study this process at the earliest stage, the progeny of 3 different broodstocks obtained from wild parents, selected farmed abalone and randomly sampled farmed abalone, were studied. After rearing for 16 mo in separate tanks, offspring from the 3 progenies were placed together in sea cages at the same density. After 3 yr, behavioural traits were studied, and the immune status after a stress situation was assessed. Mortality and growth were also recorded. In spite of the fact that no significant differences were observed in survival, growth or immune status traits between the 3 progenies, less progeny from the selected broodstock performed the complete sequence of anti-predation behaviour, and they took more time to reach their hides compared to the wild progeny. In addition, the shell colours of the selected progeny were more orange and had more stripes compared to the brown-green colour of the wild progeny. Progeny of randomly sampled broodstock showed intermediate responses between those of wild and selected progeny. Our results suggest that associated behavioural trade-offs can take place after only one generation of selection to improve growth. This should be taken into consideration when using selected stocks for ranching or population enhancement programs.