Exploring economic feasibility of marine-based organic fertilizers: Expert insights from industry informants

Worldwide, fisheries and related industries produce large quantities of marine residues, such as fish cutoffs, heads and backbones, often ending up as waste or only extracting the fish oil and soluble protein via hydrolysis, leaving sediment of bone particles, etc. unused. However, research and practice show that these residues can be applied as fertilizers with an immediate effect on plant growth. If production of fertilizers is economically viable, utilization of marine residues can be improved and simultaneously meet a demand for fertilizers in certified organic farming. This paper analyzes economic viability of producing marine-based organic fertilizers in Norway and Denmark. From interviews with fertilizer producers, the willingness to pay for one kilogram of an acid preserved bone material of captured white fish, made from minced heads, backbones, skin, organs etc., appearing as a residue product when extracting fish oil and soluble proteins during hydrolysis, was identified. With an average N-content of 4.2%, a positive willingness to pay was identified, between 0.078 and 0.272 €/kg, dependent on market conditions. With the positive willingness to pay, it may be economically viable to apply the material to produce marine-based organic fertilizers, revealing a potential for further exploitation of the by-products from captured white fish for fertilizers in certified organic farming.