Abstract:To study the influence of light trapping technology on the quality of fishes cultured in deep-water cages, light trapping equipment was designed and installed in deep-water cages in Qingdao. Light trapping equipment involves green LED light (wavelength 525~530 nm) installed on the cage to attract live prey in the sea, providing natural food for the cultured fishes inside the cage. In this study, three important fish species were selected: Pseudosciaena crocea, Lateolabrax japonicus, and Pagrosomus major. Since there were no artificial feedings throughout the culture period, the fishes are in a semi-wild growth state. The quality of the cultured fish was determined by measuring the fat, fatty acid, and amino acid content of the specimens in the treatment cages (equipped with light trapping equipment) and traditional cages (with artificial feedings and without light trapping equipment) after a 5-months’ culture period. The results showed that the sensory characteristics of P. crocea, L. japonicus, and P. major in the treatment cages were significantly better than the fishes in traditional cages. The body fat of the three fishes cultured by light trapping technology were significantly lower than those of the control groups (P<0.05). The crude fat contents in the muscles of P. crocea and P. major cultured in treatment cages was 75.24% and 46.81%, which were significant lower than those of traditional cage culture fishes (P<0.01). There was no significant difference in the crude fat content in the muscle of L. japonicus (P>0.05). The docosahexaenoic acid content in the muscles of P. crocea, L. japonicus, and P. major in treatment cages were extremely significant higher than those in fishes cultured in traditional cages (P<0.01). Moreover, the total fatty acid content and palmitic acid content were significantly lower than those in fishes cultured in traditional cages (P<0.01). Under the influence of light trapping equipment, the indices including the contents of taste amino acids, umami amino acids, sweet amino acids, total amino acids, and non-essential amino acids in the muscles of the three fish species in the treatment group were significantly higher than those of the traditional groups (P<0.05). And the contents of flavored amino acids, umami flavored amino acids and sweet flavored amino acids in P. crocea in the treatment groups increased 11.78%, 9.17%, and 19.57% than those in traditional groups. Moreover, the difference was significant. All the results show that although the deep-water net cage fish culture technology with light trapping reduces the growth rate of cultured fish, but it can improve the fish quality and increase output efficiency. The system could be used to promote and apply a green and healthy aquaculture model.
