Sustainable Production of Feed for Recirculating Aquaculture using Black Solider Flies and Microalgae

The demand for high-quality, nutritious food continues to increase as human populations grow. As wild fisheries are depleted, aquaculture production is growing to meet the demand for seafood. Sustainable alternatives to wild caught fish meal are increasingly valued for aquaculture feed production. Microalgae and insect larvae are both valuable sources of fatty acids in aquaculture feed. Black soldier fly larvae, Hermetia illucens (L.) are used to convert organic waste streams into insect-based animal feeds. We tested their ability to retain alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) from feeding substrates, which has important implications for their use in aquaculture. When supplementing a chicken feed diet with increasing concentrations of salmon oil (0 - 42%) over an increasing number of days (0 - 8), the concentrations of the three Ω-3 acids in larvae increased significantly. Larval survival and biomass accumulation were not affected. Supplementing a chicken feed diet with increasing concentrations (0 – 14%) of Tetraselmis chuii microalgae paste also significantly increased ALA and EPA contents of the harvested larvae. However, microalgae also decreased survival, harvested biomass, and individual growth of larvae feeding on the diet with the highest supplement concentration (14%). DHA was not detected in any microalgae diet or subsequent larval tissue samples. An automated, 1,700L photobioreactor system for microalgae production is described along with its performance in producing Tetraselmis chuii. A second system is described for producing black soldier fly larvae with automated moisture control of rearing substrate. The performance of the system is also described