Growth rate, condition index, and cultural potential of the brown mussel Perna perna (Linnaeus, 1758) reared in a submerged longline system in Dakhla Bay, Morocco

This study is designed to monitor the zootechnical performance of the African mussel "Perna perna" in submerged longline at the Boutalha area in Dakhla Bay, for two production cycles carried out during the years 2019 and 2020. The first rearing cycle started on March the 26th, 2019 with a spat of mean size 19.1±3.23 mm, and a mean weight of 0.79±0.32 g. While the second cycle was launched on January the 6th, 2020 by rearing the spat of mean size 22.31 ± 3.12 mm and mean weight of 2.24±1.52 g. A sampling of mussels was done monthly for the growth monitoring and the daily monitoring of physicochemical parameters of the farming medium.  The results showed that the growth rate was almost similar for both rearing cycles, with a gain in length/ weight of about 6.57mm/2.75g and 5.98mm/2.86g, respectively for the first and second cycles. The live weight/growing rates recorded respectively for the first and second cycles, once the commercial size (60mm) was obtained,  were 20.01±5.24g/ 19.97% and 22.28±6.65g/16.83% achieving a filling rate of 38.07%/37.94%, thereafter the rearing period was 6.5 months/7 months. Regarding the production and biomass, the results revealed that the biomass per longline exceeded the value of 9.5 tons for both cycles.