because of the bay management area plan put in place to create a fallowing period and contain diseases only of the sites ie sites are active in any given year if each site was designed to have eight seaweed rafts ropes of kelps m long and supporting a biomass of kgm there would be rafts producing tonnes fresh weight fw of seaweeds with an average of nitrogen content in fw kelp tissues the harvesting of kelps would equate to the removal of tonnes of nitrogen from the ecosystem per year