Myth #2: Aquaculture uses more wild fish than what it produces
In the second of a series of Myths about Marine Aquaculture, FishfarmingXpert is reporting some of the material provided by NOAA- especially as it pertains to salmon aquaculture.
The issue of aquaculture feed and feed ingredients is often used by industry critics who commonly claim that people should eat wild salmon instead of the farmed variety, and that it takes more than one kilo of wild fish to produce a kilo of farmed salmon. They never acknowledge that it takes a lot more fish to produce a kilo of wild salmon than it takes to grow a kilo on the farm. Some of the information provided by NOAA is quoted here:
This series of Frequently Asked Questions (FAQs) addresses commonly asked questions related to feeds used in marine aquaculture. We discuss what farmed fish eat and examine issues such as fishmeal and fish oil use in aquaculture and research efforts underway to bring greater sustainability to feed production.
- What are forage fish used for?
The small, open-ocean fish that are caught in industrial fisheries are consumed directly, used as bait in commercial and recreational fisheries and in lobster traps, used as ingredients in the feed for aquaculture, pigs, poultry, cattle, and pet food; and are converted into fish oil pills.
- What are fishmeal and fish oil used for?
Fishmeal and oil are beneficial components of the diets of farmed fish. Because of this, aquaculture producers have been willing to pay more for these ingredients. As well, substitutes to fishmeal and oil have long been developed for terrestrial animal agriculture, while substitutes for aquaculture are just now coming online. With rising costs for fishmeal and oil, aquaculture producers are developing cost-effective, yet healthful alternatives.
- Does aquaculture consume more wild fish than is produced?
When aquaculture is considered as an aggregate industry, the answer is no. Globally, aquaculture uses about half a metric ton of wild whole fish to produce one metric ton of farmed seafood, meaning that aquaculture is a net producer of protein. Feed conversion ratios (the amount of feed eaten by a fish related to the amount that fish provides for human consumption) vary among species, but farmed fish are far more efficient at converting feed than wild fish or other farmed animals such as cows and pigs.
- How many pounds of other fish are required to produce one pound of salmon?
None – there is no “requirement” for fish to be in diets for farmed salmon or any other fish. It is possible to feed salmon on a fish-free diet. However, inclusion of fish in the diets of farmed salmon reflects the diet of wild salmon and confers the nutrient benefits associated with eating salmon. Until replacements (such as algae) with nutritional elements similar to fishmeal and fish oil are commercialized, salmon and marine fish will need some fishmeal and fish oil in their diet. However, researchers are making significant progress in reducing the amount of fishmeal and fish oil used in the diets of farmed seafood while maintaining the human health benefits.
The answer to how much is used (as opposed to required) is a moving target, depending on how much fish meal and fish oil is used in any particular salmon diet. Recent data indicates reflects that the production of one pound of farmed salmon uses the fish oil from about five pounds of wild fish (depending on the oil content of the species used), but the fishmeal from only 1.3 pounds of fish. The excess fishmeal from those wild fish is used in the diets of other farmed animals.
Considered in the aggregate, aquaculture uses about half a metric ton of wild whole fish to produce one metric ton of farmed seafood. The amount of fish you get “out” (as seafood) relative to the amount of fish you put “in” (in the diet) – known as “fish-in/fish-out” (FIFO) conversion ratios – vary greatly among species. Piscivorous fish – especially those new to aquaculture – require more fishmeal and oil in their diet than omnivorous species.
