During the low temperatures that appear in the winter season at the Mediterranean level, marine aquaculture fish, in addition to having to endure these conditions for several weeks, must also face possible sudden drops in these temperatures.
However, drops in water temperature are not the only factors that influence the wellfare of production fish during the winter. The previous immune status of the animals and the stress conditions associated with intensive production (management, fishing, high density) are very important during these moments. Sea bream is a species that is especially affected by cold water temperatures, both physiologically and metabolically.
Consequently, there are numerous problems that can appear during the production of this species at temperatures below 14 degrees. One of these problems is the Ulcerative Cutaneous Rash, an inflammatory skin disease of sea bream, which causes lesions and open wounds on the body. This disease is usually highly prevalent on the Mediterranean coasts, and although it has a benign and subchronic course, it can cause mortality for several weeks.
Another of the drawbacks of this process are the external wounds and injuries that cause rejection in the sale of the fish. It is not surprising that in these conditions, sea bream are more susceptible to infections by microorganisms (it has been related to Pseudomonas anguilliseptica, but this bacteria is usually present at times of lower temperatures and salinity instability), but the Ulcerative Rash is not caused by a specific pathogen. It is a multifactorial pathology of unknown etiology, which can also lead to metabolic collapse, organ dysfunction and immunosuppression mainly due to low temperatures and reduced intake. Of course, open wounds are gateways for secondary bacterial pathogens.
In the latest studies carried out to prevent the appearance or accelerate the healing of wounds, the potential of the amino acid methionine has been identified, being this a biomarker for wound healing. A correct level of methionine in the skin mucus of injured fish increases the healing process of wounds.
Another way that can accelerate the healing of these lesions is to supplement the feed formulas with arginine, and of course apply the best possible production and animal welfare conditions within each facility, giving special importance to a medium/low density.