How New Breakthroughs in Fish Feed Are Ready to Make Aquaculture Even More Sustainable

The biggest production cost for all fish farmers is feed. For finfish like salmon, the feed has historically been fish oil and fish meal made from wild stocks of forage fish – small pelagic fish that live in the upper layers of the sea, such as anchovies, sardines, menhaden, capelin, and herring. This has generated many complaints about robbing Peter (forage fish from the ocean) to pay Paul (the ravenous salmon growing to adulthood). The concern is that an over-reliance on wild forage fish to feed farmed fish will disrupt aquatic food webs and limit growth of wild-fish stocks.

Michael Rubino, however, considers the argument against fish oil and fish meal a “red herring.” Rubino, senior advisor for seafood strategy at NOAA Fisheries and its former director of aquaculture, contends that the supply of fish meal and fish oil on the global market has been relatively constant for the last 30 years, even as aquaculture production has increased by about 5 percent per year.

“It wasn’t ever really an issue,” says Rubino. “If salmon farmers didn’t buy it, producers of pigs and chickens and pet food would. Now, aquaculture feed has been decoupled from the need for forage fish, thanks to work NOAA Fisheries and industry scientists have done in the last 15 years.”

New Alternatives

Since 2000, the percentage of fish meal and fish oil in aquaculture feed has declined from 70 percent to 30 percent.  Many farmers have turned to corn- or soy-based protein for growing fish, but these alternatives can lead to higher fish mortality and generally suboptimal growth. And farming soy and corn means often means clear-cutting pristine forests, such as in the Amazon.

But a number of alternative feeds are promising. These include insect larvae, microalgae, fermented CO₂ and biotech single-cell proteins.

Knip Bio, based in Lowell, Massachusetts, has developed microbe strains that convert ethanol, methanol and other feedstocks into single-cell protein. KnipBioMeal combines the attributes of fishmeal and carotenoids, which give salmon its pink color. “It’s really pink flour,” says Larry Feinberg, co-founder and CEO. “‘Knip’ is ‘pink’ spelled backwards.”

NovoNutrients, an early-stage biotech company in Mountain View, California – down the road from Google and Facebook – is looking to turn CO₂ emissions into protein for seafood farming. Its Novomeal, a nutritionally complete substitute for fishmeal, is made from the proteins of bacteria and other single-celled organisms that are incubated in bioreactors, giant steel vessels akin to beer vats. The lab-created bacteria feed on carbon dioxide.

In Menlo Park, California, Calysta ferments natural gas with naturally occurring bacteria to create a protein feed called FeedKind. It has been shown to be an ideal feed supplement for Japanese yellowtail or hamachi, a sushi staple. FeedKind has also been used successfully to feed salmonoids and shrimp.

Insects are part of the diet of wild fish and crustaceans and are now being used in aquaculture. Black soldier fly larvae, for example, provide an inexpensive, high-protein alternative to fish-based feed. Distributed by several companies in Africa, black soldier fly larvae will eat just about anything, including waste, and in 14 days build up fat stores that sustain them for the remainder of their adult lives. One scientific study showed that “a total replacement of fish meal with black-soldier-fly larvae meal in the diets of Atlantic salmon was possible without negative effects on growth performance, feed utilization, nutrient digestibility, liver traits or the sensory qualities of the fillet.”

French company Ÿnsect produces premium oil (Ÿnoil) and meal (Ÿnmeal) from the larvae (mealworms) of Tenebrio molitor, a species of beetle. Both are designed for fish feed. BetaHatch in Seattle, Washington, converts mealworms and their waste into high-value proteins, oils and nutrients for both agriculture and aquaculture.

Cautiously Optimistic

The aquaculture industry at large is excited by these developing products – given the negative blowback about forage-fish feed – but individual farmers cite two reasons to proceed with caution. One is that they are waiting for evidence of the long-term success of the feeds. Another is that they worry about whether these new providers will scale production to provide a consistent supply of feed, because missed shipments could have a serious impact on the health of their fish. The actual ability to scale is not the issue, as the technologies appear solid – but a company needs a steady stream of large customers to justify scaling production. Thus, there is a chicken-and-egg problem hindering future development.

Whatever the feed, fish in general are a much more effective converter of food to protein than land animals. Beef has an average food-conversion ratio of 6:1, pigs 4:1, and poultry 2:1 – while fish overall are less than 1:1.

Sebastian Belle, executive director of the Maine Aquaculture Association, attributes the food-conversion advantage of fish to their physiology.

“Finfish and shellfish have two major advantages over land plants and animals: They don’t have to thermoregulate, or burn calories to maintain heat, and they use air or lipids to fight gravity, which means they preserve calories and energy,” says Belle. “Take the two together and it’s clear why it’s inherently more efficient to grow food in water than on land.”