Fish Hydrolysate

The new technology that has increased fishing efficiency has also resulted in the taking of species or sizes not suitable for market, known as the bycatch. An increased catch of unsaleable whole fish has resulted from the increased bycatch of the fishing industry. These fish are often dumped overboard at sea, but are also brought into port in the holds of fishing boats. This has created an incentive to find a market for the bycatch in order to lower the cost of production.

Unfinished fish hydrolysate; photo from Third Insight Design and Nursery

The liquid fish hydrolysate process minces the residue from target fish (after filets removed), plus the bycatch fish, then enzymatically digests, grinds and liquifies the resulting product, known as gurry. Because it is a cold process, gurry breaks down more rapidly than fish emulsion and needs to be stabilized at a lower pH, requiring more acid. Researchers have tried formic acid, sulfuric acid, and others. Formic acid had phytotoxic effects on plants. Phosphoric acid is the preferred stabilizer. The hydrolysate process has substantially lower capital and production costs than fish emulsion production.

From the Laidback Gardener: "Hydrolyzed fish is made from fresh fish harvested the same day, broken down by natural enzymes, then stabilized, which explains the lack of odor, as fresh fish doesn’t smell bad."

Want to try making your own? Iin involves fish, molasses, lactic acid bacteria, and water. Here is a formula from Third Insight Design and Nursery: How to make Fish Hydrolysate.

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