Large-scale mariculture of the sponge Haliclona simulans on floating rafts in Zhao'an Bay, Fujian Province, China

Marine sponges are an important source of bioactive products and biomaterials. However, there is a bottleneck of biomass supply for sponge utilization. To overcome this bottleneck, mariculture was considered to be the most viable solution. Mariculture of the marine sponge Haliclona simulans was conducted on floating rafts in Zhao'an Bay, Fujian Province, China. The explants were suspended 0.5–2 m below the water surface to grow naturally using the mesh method. Two independent trials with different scales were performed in this study. In a small-scale trial with 30 sponge explants, with daily maintenance, the survival rate of H. simulans was 93.3% over 224 days. To determine whether harvesting twice yearly yields greater output than annual harvesting, the 30 H. simulans were randomly divided into two equivalent groups. The annual harvest group (1 harvest per year, 1PY) was harvested in 224 days, and the twice harvest groups (2 harvest per year, 2PY) were harvested at 92 days and 224 days, with approximately 30% of the biomass was retained during the first harvest to allow regrowth. The results showed that the total biomass accumulation rate was 629.27 ± 256.74% for the 1PY group and 1014.73 ± 252.56% for the 2PY group. The biomass accumulation rate of 2PY was approximately 61.26% higher than that of 1PY. To obtain more accurate yield data under industry scale, a large-scale mariculture was independently conducted with about 7500 explants and covered a sea area about 500 m2, in which each area of 0.2 m2 was occupied by a horizontal rope, and each rope held 3 vertically suspended explants. Lost or dead explants were replanted during routine maintenance. A total of 330 kg wet weight biomass was obtained from the first harvest after 92 days of cultivation, and 272 kg wet weight biomass was obtained from the second harvest after 224 days. A total of 45.05 kg dry weight sponge was obtained after drying. This finding indicates that under our mariculture methods and harvesting strategy, the yield of H. simulans can reach approximately 900 kg dry weight biomass per hectare per year. This research provides valuable data for large-scale sponge production and new methods for the industrial development of sponge products.