The other half of the pie: agricultural feed inputs

Most of the feed given to farmed salmon isn’t fish. In fact, fish inputs make up a smaller and smaller portion of most salmon feeds and in Norway are around 30%. While the focus of this blog is the use of fish as feed in livestock and aquaculture, it is important to consider other parts of the equation. In this post, I will cover what makes up the other portions of commercially produced fish feeds, namely land-based inputs. The bulk of many fish feeds today are agricultural inputs rather than fish inputs.

Norwegian Salmon Feed
Cashion et al. (2016) 

However, the impacts and concerns associated with agricultural inputs are quite different as compared to marine inputs. While I have discussed the impacts of the use of fish as feed instead of food in part, the use of non-fish inputs carry their own costs.

The food security concerns of using crops for feed are similar to using fish for feed. While animal protein and certain micronutrients are more important when considering fish inputs, the major other constituents form the bulk of calories consume globally.In general, the major inputs into commercially produced feeds are proteins from wheat, corn, and soy, and fats from soy and canola. Corn, wheat and rice are the three crops that contribute the most to humans’ caloric consumption at roughly 2/3 globally. These crops and their processed products are thus obviously important for global food consumption, but in a different way from fish products. Fish products are often consumed for their high-quality proteins and micronutrient content (such as Omega-3s in addition to other vitamins), rather than to form the bulk of the calories of one’s diet.

Brassica rapa
Canola is now a major fat source for aquaculture diets

To grow fish in aquaculture, a certain nutritional balance must be sought but there are also fundamental constraints about how that feed can be converted into biomass of the fish. In other words, there are limits to how much we can reduce the amount and energy content of feeds and still get out the same quantity of fish at the end of the day. Recent advancements have been made at reducing the ‘feed conversion ratio’ (e.g., the amount of feed given to the animal compared to the amount of animal food we get out) and at reducing the fish content of certain feeds, but these result in a shifting of the burdens associated with them. A reduction in fish content (be it meals or oils) is often paired with a substitution of agricultural inputs such as increased soy protein or canola oil. While this reduces demand on marine ecosystems in this form, it also increases the demand for these agricultural products. For the displaced environmental burdens, this is called ‘environmental problem shifting’ where pressure and impacts are shifted from one part of the system to another. While substituting fishmeal protein for soymeal protein can reduce pressure on marine ecosystems, the increased demand for soy globally is causing increased conversion of sensitive ecosystems into agricultural land for soybean production, such as in the extreme example of the clearing of the Amazon rainforest to grow soybeans.

However, if the feed conversion ratio can be improved, this means that less input is required to produce the same amount of desired end product. This reduces costs not only for the farmer, but environmental costs associated with producing these inputs in the first place. As fish inputs into aquafeeds are often the most costly, feed developers and farmers that produce their own feed want to minimize fish inputs while not compromising on the feed conversion ratio or the quality of the final product. When not enough fish inputs are included the result can be a slow growth rate and/or a low-quality product that might not appeal to consumer’s tastes. By reducing the length of time the species is farmed before it can be sold, fish inputs can improve the economic and environmental performance of aquaculture in some areas.

While many contest the use of fish as feed inputs in aquaculture, they should be used to maximize food security outcomes across these different methods of food production including capture fisheries, aquaculture, and terrestrial food production. When considering the reduction of fish inputs to aquafeeds, it must be balanced by knowing that if the same production is going to continue those other inputs need to come from somewhere. It is thus not enough to minimize fish inputs to fish farming, but we must seek to minimize the environmental, social, and economic costs associated with seafood production.

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