Stress response of farmed European abalone reveals rapid domestication process in absence of intentional selection

Farming, and thus the domestication of Haliotis tuberculata, began recently. We compared the responses of unselected farmed and wild abalone to stressors that occur on farms. The aim was to determine if the farm environment had induced differences in the behavioural or physiological performances of the abalone. Thirty hatchery-born 3.5 year-old abalone and thirty wild ones were reared under standard farm conditions for 6 months and characterised for 19 traits related to growth, survival, behaviour and immunology. Behavioural and immunological responses to stressors differed between the two stocks. Farmed abalone retracted and swivelled less in reaction to a finger contact. Phagocytosis efficiency was reduced by shaking in abalone from both origins, but the farmed stock returned to the basal level after the recovery week, while wild abalone did not, and a rise of total haemocyte count after shaking and its return to a basal level after one week was only observed for the farmed stock. This indicates that both behaviour and immune responses following a stress have been affected by the farming practices. This suggests that a domestication process has already been initiated in the farmed stock. Our results may also be important for the success of any population enhancement based on hatchery-produced abalone as they raise the question of the capacity of abalone with a fanned origin to be adapted to the wild environment.