To meet the increasing demands for seafood , as well as in maintaining a sustainable source of protein for global populations , the aquaculture industry must expand and develop new resources. As aquaculture farmers races to meet these new demands, the pharmaceutical industry must deliver an ever-increasing portfolio of drugs required to maintain organism health and wellbeing. To date the US Food and Drug Administration has reviewed and approved approximately 16 compounds to combat a multitude of target conditions . Targets are primarily directed at bacteria, fungi, and parasites (external and internal). Other approved drugs are used to mark skeletal and bony structures in vertebrates for identification , and to promote or manage spawning activity. Most drugs are administered through feed or via infusion into the aquatic media. Because aquaculture organisms are primarily developed as food resources for human consumption, their administration, residual tissue concentrations, and monitoring are vital for safety. Equally important are environmental concerns for waste handling and final degradation of excess compounds.
As new drugs are developed and prepared for approval, several important considerations must be evaluated. The type and size of the system, the farmed species, and the target disease prevention are all key factors that will drive the decision to the right application. In a survey of facilities in North America and the North Sea approximately 77% of facilities were designated as flow through (FT) systems, 12% were recirculating aquaculture systems (RAS), and 11 % a combination of FT and RAS. Specifically looking at salmonid hatcheries, seven hatcheries in North America together produced approximately 14.9 million salmon smolts, totaling 1,188 metric tons of fish per year . Once administered, the drugs action is through systemic or extrinsic exposures. Studies are needed to determine the degradation rate and daughter products of pharmaceuticals. For example, some drugs can be excreted through fecal material in a fully ac tive form, while others may exist only in a partially active form. Additionally , fully active drugs may also be present in uneaten food. Either way, laboratory studies must be carried out to fully understand the degradation pathways and exposure potential within FT or RAS systems.
Once degradation is understood facilities must be able to determine how to manage the waste. In both FT and RAS systems fecal material and sludge are the largest waste. Often this can be managed through public treatment systems; however, those that cannot must collect and manage waste. In a survey of facilities, many collected biosolids as a secondar y product to sell to land farms. This can introduce certain degradation products or fully active chemicals directly to the environment. Several options for waste management exist for facilities including, drying, containerizing, heating, and filtering.