Salmon. From the aquaculture side, let’s look at salmon farming. As carnivores, salmon historically were fed diets derived largely from fish meal and fish oil. With the rapid growth of salmon farming that started in the mid 1980s, it became clear that catching wild fish to feed farmed fish isn’t sustainable from either an environmental or a business perspective. As a result, salmon diets have changed dramatically over the last decade with fish oil and fish meal being replaced by vegetable oils and proteins, largely canola and soy, respectively.
To raise a pound of a vegetarian salmon, one raised on a diet of canola oil and soy protein, the fish would consume 0.84 pounds of canola seeds and 0.69 pounds of soybeans. However, most of us eat salmon filets so, actually, we really only eat about 64 percent of the whole salmon. That means it takes about 1.3 pounds of canola seeds and 1.1 pounds of soybeans to put a pound of salmon on the dinner table.
Red meat. Beef and pork have diets that include many cereal crop ingredients. As a useful simplification, I combine them together as one entity: cereals. With that said, a pound of pork we eat consumes between 2 and 3 pounds of soybeans plus 5 or 6 pounds of cereal. Beef cattle, raised on feedlots starting at 500 pounds up to their harvest weight of 1,300 pounds, need about 10 pounds of cereal to provide a pound of edible meat.
Poultry. It takes 2 pounds of feed to raise a pound of chicken. Of that pound of chicken, about 50 percent is meat and skin, so it takes about 4 pounds of total feed to put a pound of chicken on a plate. However, chickens, as omnivores, have a more complex range of dietary ingredients including other animal byproducts. So, their use of crop plants is certainly less than 4 pounds.
As we consider resource utilization in our future food supply, quite clearly salmon offers the promise of producing a lot more food with a lot less input. This makes sense. For a few reasons, fish are the most efficient of farm animals. They don’t use any energy to maintain their body temperature as land animals must. Another energy benefit for fish is that they don’t spend calories working against mavity. Furthermore, the freedom from mavity also removes the need to spend energy building a bone structure to support their weight. So, we eat a much greater fraction of a small-boned fish than we do from large-boned land animals.