Effects of husbandry conditions on the skin colour and stress response of red porgy, Pagrus pagrus

• Published in: Aquaculture Vol. 241; no. 1; pp. 371 - 386
• Main Authors: Van der Salm, A.L., Martínez, M., Flik, G., Wendelaar Bonga, S.E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 26-11-2004; Elsevier Science; Elsevier Sequoia S.A
• Subjects: alpha-melanocyte-stimulating hormone; Animal aquaculture; Animal productions; Aquaculture; Background adaptation; Biological and medical sciences; blood plasma; color; cortisol; Crowding; fish culture; Fundamental and applied biological sciences. Psychology; General aspects; glucose; lactic acid; Light intensity; Light spectrum; mariculture; Marine; marine fish; osmolarity; Pagrus pagrus; pigmentation; Population density; Skin; Skin colour; Sparidae; Stress; Light intensity; Light spectrum; Background adaptation; Pagrus pagrus; Crowding; Skin colour; Color; Environmental factor; Stress; Marine environment; Vertebrata; Pisces; Light; Rearing; Skin; Adaptation; Aquaculture
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2004.08.038

Red porgy,
Pagrus pagrus, is a potential candidate for aquaculture. However, darkening of the body occurs after capture of wild fish and during farming of cultured animals. In fish, skin pigmentation is hormonally controlled and the main hormone involved in skin darkening, α-melanocyte-stimulating hormone (αMSH), is not only involved in pigmentation but also in the regulation of the response to stressors. In this study, several environmental conditions were evaluated for their potency to influence the skin colour and to evoke a stress response. Background colour was the main factor in controlling skin pigmentation. A light background colour restored the lightness value of the skin up to levels found in wild red porgy (
L*=∼70). The background effect was enhanced by applying blue illumination. Light intensity had no clear effect on the body colour, but a high density of fish had a negative effect on the lightness. Plasma parameters (cortisol, αMSH, glucose, lactate and osmolality) were not influenced by background colour. A stocking density of 25 kg/m
3 did not evoke a stress response in contrast to earlier studies on red porgy, nor influenced the body colour. We propose that this difference can be attributed to the number of fish per volume of water, which was lower than in other studies. This indicates that the number of fish per volume of water rather than the density in kilograms of fish per volume of water is the relevant factor. Furthermore, we suggest that the culture of adult red porgy can be optimised by maintenance of fish on a light background, thereby restoring the body colour to a more natural hue, without affecting the stress response.