EnriFish - An innovative environmental enrichment for the health and welfare of farmed trout

Context and challenges

The search for preventive and sustainable methods that reconcile pathogen control and fish welfare is becoming a priority for the fish farming industry. Environmental enrichment aims to improve the psychological and physiological needs of a captive animal by increasing the complexity of its environment. Although this practice already exists in land animals, the fish farming industry has not yet adopted it, probably due to a lack of scientific knowledge and specific regulations concerning fish welfare. In addition, enrichment by adding complex structures to the tank requires maintenance and may constitute a bacterial reservoir that may affect the health of the fish, which would also explain the reluctance of the industry to implement these practices. In the EnriFish project, we will study the effects of an innovative enrichment consisting in introducing in the tank from the first stages of life a pipe generating a curtain of bubbles, since preliminary observations have shown that fish are attracted to areas where there are bubbles. We will evaluate the short- and long-term impact of these bubble curtains on growth, innate immune response, parasitism, as well as on fish behaviour and stress response. The focus will be on the observation of aggressive behaviours that we believe can be limited since they can be sources of injury and stress impacting the immune system. This type of enrichment would allow to integrate the notion of "positive welfare" in breeding by encouraging the expression of playful behaviours, while guaranteeing an easy maintenance and good health of the fish.

Objectives

1. To determine the impact of a bubble curtain introduced in the environment of immature trout on welfare-indicating behaviours, emotional responses and growth after 4 and 8 months of exposure.
2. To relate the phenotypes induced by this enrichment with the innate immune response capacities following the administration of bacterial and viral immunostimulants, using transcriptomic approaches.
3. To highlight the possible existence of play behaviours during the diffusion of bubbles by observing fine behaviours (fin movements, mouth opening, etc.)

Species concerned

Partnerships

• UR LPGP, INRAE, Département PHASE : éthologie, évaluation du bien-être de la truite
• UMR VIM, INRAE, Département SA : immunologie, infectiologie
• UR AFPA, INRAE, Département PHASE : physiologie du stress
• UE PEIMA, INRAE, Département PHASE : conduite d’élevage, paramètres de croissance, parasitisme