A lot of people normally tell me that aquaculture will "replace" fisheries, something that I usually dispute. Since many of the present commercially aquacultured species still depend on fish meal and oil for their feed. Hence in the best case scenario, they will complement each other. Yet aquaculture is not the only "user" of fish meal and oil, hence it "growth" also depends on the use by other food producers.
(left) Consumption of wild-caught forage fish by species groups, showing how pigs and poultry still consume large supplies. (right) The dominance of mainland China as a consumer of forage fish feed
The intricacies between these users were researched by Halley Froehlich, Nis Jacobsen, Tim Essington, and their coauthors, in the journal Nature Sustainability. Below I quote in this paper as reported by the University of Washington SAFS.
Some types of aquaculture-raised (farmed) fish and crustaceans rely on wild-caught fish as feed for omega-3 fatty acids and micronutrients. But with the rapid and continuing rise of aquaculture, and the natural limits to the supply of forage fish (anchovies, herring, and their relatives), eventually this supply of feed will be exhausted.
This study now highlights ways in which the supply of fish food can be eked out further by:
- reducing the proportion of feed that is based on wild-caught fish and switching to crop-based diets such as soy;
- Increasing catches of forage fish to maximum sustainable levels, adding 30% more catch compared to 2012 levels;
- eliminating the addition of wild-caught feed to non-carnivorous farmed species;
- eliminating forage fish from pig and poultry diets;
- using trimmings from the processing of other wild-caught species as food for farmed fish; and
- Increasing the efficiency of farmed fish production.
These adjustments offer a variety of pathways to ensure that forage fish are able to support aquaculture growth beyond the year 2050.
(top) Total mass of food produced from pigs, poultry, and aquaculture species fed using wild-caught fish. (bottom) Dramatic changes over time in the use of fishmeal from wild-caught forage fish, showing how farmed fish are now the largest consumers of this feed source.