[imtringued]

This is a problem with pretty much every type of factory farming. Food can be cheaply imported from any country around the world but the animals still produce feces locally. The factory farm owners do not own any land to use this natural fertilizer on. Therefore it is either stored in lagoons or in case of aquafarms just sinks to the bottom of the water until years later it becomes impossible to farm fish anymore because of excessive algae blooms.