Characterization of wound healing in Atlantic salmon (Salmo salar) post-smolt, and the effect of stress on the healing process

The aim of this study was to assess the effect induced by high fish density on cutaneous wound healing in post-smolt Atlantic salmon. Our findings suggest that high fish density enhances inflammation and represses cell proliferation, tissue secretion and collagen synthesis in the healing wounds. These processes are further manifested in the different layers of the skin, such as delayed re-epithelialization, altered mucus response, reduced scale mineralization, enhanced wound pigmentation and delayed organization of dense connective tissue. Temporarily changes in wound healing mechanisms result in permanent differences in wound contraction. In conclusion, our results show that high fish density dispose the fish for an enhanced immune response and delayed tissue repair, which ultimately results in delayed wound healing. Fish were wounded with a 5 mm skin punch biopsy needle and stocked at two different densities, high fish density (100 kg/m3) and control (20 kg/m3). Samples were collected before treatment and at seven time-points: 1, 3, 7, 14, 36, 43 and 57 days post wounding (dpw)