Fertilisers from aquaculture and other marine waste

Summary

Seafood processing generates significant volumes of residues
including bones, heads and other non-consumable fish parts, rich in nitrogen, phosphorus and calcium. Some
residues are recycled to aquaculture or animal feed, but around 4 000 tP/y in Norway are currently not valorised.
Nitrogen, potassium and magnesium can be extracted from
brown seaweed (harvested or cultivated), and combined with
processed seafood by-products to produce a nutrient-balanced
recycled fertiliser, which has shown positive results in
agronomic trials. These marine sources represent significant potential for nutrient recycling in coastal countries. Certain seafood processing byproducts are specifically authorised for use as fertilisers in the EU Organic Farming Regulations: fish meal – without limitations, mollusc waste and shellfish chitin from organic aquaculture or sustainable fisheries only, seaweed and seaweed processing by-products with some restrictions.