Background. Atlantic horse mackerel, Trachurus trachurus (Linnaeus, 1758), is among bento-pelagic species subject to discard within deep-water rose shrimp fisheries, and how such species would react to light wavelength is therefore important, to be consistent with the Common Fishery Policy (CFP). Despite the existing literature currently available, there is still paucity of relevant information about how artificial light wavelengths affects the behaviour of T. trachurus juveniles. In this context, the effects of different artificial light wavelengths on some behavioural features of juvenile T. trachurus were investigated. Materials and methods. Maintained in a fish tank, the juveniles of Atlantic horse mackerel, after acclimatization, were subject to six different light wavelengths, representing the following colours: white, violet, blue, green, yellow, and red. Subsequently, behavioural features, specifically phototaxis (degree of attraction or repulsion toward the light source) were tested. Results. By phototaxis per light wavelength, the studied juvenile individuals produced statistical differences in the presence frequency (P < 0.05) revealed by blue that noticeably attracted some, relative to the white light that repulsed others. Yet, violet and red lights produced much less but no significant attraction of these juveniles (P > 0.05). Conclusion. The presently reported study has provided additional information about ecological knowledge and understanding specific to juvenile T. trachurus individuals, which can further the development of (selective) light fishing techniques, aimed at reducing unwanted catches of commercial pelagic fisheries.

trawl fishery, horse mackerel, artificial light, attraction, repulsion