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The research carried out in the context of this programme should help to overcome the technological and scientific obstacles encountered by the fish farming sector in Europe, and thus improve farming practices and establish new selection criteria for the main commercial species such as sea bass, sea bream, Atlantic salmon and trout. The results obtained should also favour the domestication and farming of new species, such as cod and halibut.

The programme focuses in particular on a certain number of obstacles:

• control of larval quality and a reduction in their mortality rates,
• improvements in feed efficiency and flesh quality,
• improved control of the sexual status and puberty of different species,
• improvements in resistance to stress and diseases,
• the optimum adaptation of fish to their raising conditions.

To achieve this, the researchers are working on three major areas of the life cycle of fish using physiological and functional genomics approaches.

They are focusing on the early stages of life in fish to understand the onset of the mechanisms that underlie larval development. The particular aim is to understand:

• the effects of maternal mRNA in oocytes on the quality of early embryonic development,
• how environmental conditions influence development of the musculoskeletal system,
• how sexual differentiation is triggered.

To a great extent, these mechanisms condition the survival of larvae and also the problems that intervene in adulthood and those that are linked to disease resistance, reproduction and the ability to adapt to environmental change.

Growth and adaptation to the environment during the juvenile and adult stages constitutes another area of research. Poor adaptation to the environment causes poor growth in farmed fish, with low feed efficiency and problems with flesh quality. An understanding of the constitution of different flesh compartments (adipose tissue, muscle) will be addressed via hormone regulation. While the costs of feed continue to rise, achieving optimum growth of the animals is an objective of prime importance to maintaining the competitiveness of European aquaculture.

Finally, this programme is also focusing on transition periods, such as metamorphosis, smoltification (the adaptation of fish to salt water after growing in fresh water) and, more particularly, puberty. These critical stages in the organism cause major problems in farming, such as reduced disease resistance, higher mortality and impaired growth. For this reason, a clearer understanding of the regulation of osmoregulation (ion balance) and the immune system during these periods, and a better control of puberty, are important factors in this sector.

Two Inra units are involved in this programme :

• UR1037 Joint Research Unit for Fish Physiology, Biodiversity and the Environment (SCRIBE)
• UR 892 Research Unit Molecular Virology and Immunology Unit (VIM),and more particularly the Fish Infection and Immunity group (IIP)