Biotechnical Aspects of Aquaculture Production of Common Meagre Argyrosomus regius in Floating Cages in Dakhla Bay, Morocco

Abstract This study is the first contribution to monitoring the rearing of common meagre Argyrosomus regius in floating cages anchored in Dakhla Bay, southern Morocco. The aquaculture potential of common meagre in Dakhla Bay was evaluated by zootechnical monitoring of two production cycles. The first batch consisted of 20,000 fingerlings of 4.5 ± 0.13 g in mean initial weight and 6±0.19 cm in fork length, and was caught on 26 August 2019 under a condition factor of about 2.08 ± 0.35. The second batch consisted of 30,000 individuals of 3 ± 0.11 g in average initial weight and 6±0.26 cm in average initial length, and was caught on 4 June 2020 under a condition factor of about 1.39 ± 0.21. During the first experiment, which lasted 16 months, a high growth potential of common meagre was observed. The fish reached an average weight of 1265 ± 69.2 g and an average length of 48±4.32 cm with a specific growth rate (SGR) of 0.58 ± 0.11% day-1 and a daily growth index DGI of 2.45 ± 0.91 g ind-1 day-1. The feed conversion ratio was 1.18 (FER = 0.84), final density was 36.94 kg m-3 and condition factor (k) recorded a mean value of 2.18±0.39 throughout the cycle. The survival rate at the first harvest was 89.86%. After 18 months of rearing, the fish of the second cycle reached a weight of 1285±69.2 g and a size of 47 ± 5.36 cm, with an SGR of 0.49 ± 0.12 % day-1 and a DGI of 2.34 ± 1.35 g ind-1 day-1, an FCR of 1.21 (FER =0.83), the final density of 28.43 kg m-3 and a condition factor of 1.35 ± 0.32. The survival rate was 92.19%. However, the results of the statistical analysis showed that there was no significant difference between the two production cycles (P > 0.05). These results confirm that common meagre is a very promising species for the diversification of aquaculture in Dakhla Bay and throughout Morocco.