Aquaculture Discharge

Aquaculture discharge is the effluent released from fish and shellfish farms, carrying dissolved nutrients, suspended solids, uneaten feed, feces, therapeutants, and antifoulants into receiving waters. Net-pen finfish farms release ammonia and phosphate that drive localized eutrophication, while particulate organic matter settling beneath cages causes benthic organic enrichment, sediment anoxia, and shifts in infaunal communities. Copper-based antifoulants and antibiotic residues add chemical loading. Regulators apply allowable zones of effect, benthic monitoring of redox and sulfide, and feed-conversion limits. The EU Marine Strategy Framework Directive 2008/56/EC and national permitting set the eutrophication and seafloor-integrity thresholds that govern siting and stocking density.