« September 2011 Table of Contents
Going Green: Feeding the fish
In race to find alternatives to wild fish in fish feed, soy leads the pack
By Lisa Duchene
September 05, 2011
Rick Barrows is ready to shout “Eureka!” After working more than two decades to find plant-based ingredients to replace fishmeal in aquaculture feeds, the lead scientist and nutritionist with the U.S. Department of Agriculture’s Agricultural Research Service in Bozeman, Mont., is confident science has decoded the nutritional riddle of feeding farmed fish.
“The science is there that we can eliminate fishmeal for just about any species there is,” says Barrows. “The problem is doing it cost-effectively.”
No one ingredient replaces fishmeal. But combinations of soy and soy protein concentrates, with corn (in gluten or protein concentrate form) and barley all lead the pack. In the future, the darling ingredient could be algae — which may be grown in large amounts for biofuel production — along with various yeasts and bacteria, says Barrows.
The cost of feed ingredients, particularly fishmeal and fish oil, and demand for sustainable seafood spurs the search for new ingredients. Consider the math and it’s quickly clear that finding cost-effective, environmentally sustainable ingredients for farmed fish feeds is paramount.
Prices for common fish feed ingredients like soybean meal, fishmeal, corn, wheat and rice rose by 50 percent overall since 2005, according to a 2009 report by the U.N.’s Food and Agriculture Organization (FAO). The increase for fish and other oils used in fish feeds? A whopping 250 percent.
Fishmeal and fish oil are processed from oily fish like Peruvian anchoveta and Atlantic menhaden, the catches of which have leveled off. Global fishmeal production peaked in 1994 at 30.2 million metric tons, according to FAO, and there are no signs that prices will fall.
Feed represents more than half of aquaculture production costs.
Aquaculture supplies about half the fish for human consumption and is growing rapidly. And aquaculture is under pressure to grow another 70 percent by 2050 to feed a projected global population of 9 billion.
As scientists, feed formulators and aquaculture companies evaluate each ingredient, they consider the fish’s growth rates, digestibility and omega-3 fatty acid profiles along with the ingredient’s cost, environmental footprint and whether sourcing it will place pressure on food supplies.
After decades of rolling up their collective sleeves to solve the problem, that eureka moment Barrows envisions is still elusive.
“I don’t think there’s ever going to be a silver bullet [to replace fishmeal] in any particular single raw material,” says Richard Nelson, manager of purchasing, finance and control for Nelson and Sons, in Tooele, Utah, which produces Silver Cup Fish Feeds and is owned by Nutreco, the EUR 4.9 billion ($7 billion) global animal feed producer. “I think the reality is that it will be a combination of good and better products.”
Soy leads the pack, says Nelson. “[Soy] is the most promising for now and has the greatest support from an industry group,” says Nelson.
In 2009, soy protein was forecast to grow from meeting one-third of aquaculture protein needs to supplying one-half of global requirements by 2020, according to the U.S. Soybean Export Council. Sales of soy protein concentrates, one-third of the market value of soy proteins, are projected to reach $4.7 billion by 2020.
“We’ve worked with the industry with the production sector, and with the feed manufacturing sector to develop all plant protein feeds for essentially all the major freshwater production species in China,” explained Mike Cremer, of the USSEC’s global aquaculture program, at the 2011 International Boston Seafood Show.
But soy is not without its challenges.
Soymeal has been a key ingredient in the diets of farmed catfish and tilapia. But for coldwater salmon and trout, some of the carbohydrates in soymeal interfere with digestion. Soy protein concentrates work much better, says Nelson, but the concentrate is food-grade, the same as what is used in soy-based protein shakes for people and can cost about three times that of soymeal.
Nelson would like to see a new form of soy protein concentrate that solves the digestibility problem for farmed salmon but isn’t human food-grade, so it can be produced at a volume that keeps the cost reasonable for feed producers. The USSEC says it is working on this.
Soy protein concentrate is one of the key ingredients in new feed formulations that have been tested at Clear Springs Foods. The USDA’s Barrows works closely with the Buhl, Idaho, company to test feed recipes for farmed trout, an important test species.
Coldwater species like salmon and trout evolved eating smaller fish and marine fats — not terrestrial plants — and have shorter digestive tracts that make it more difficult for them to digest carbohydrates. Warmwater species like tilapia and catfish are plant eaters. They have long digestive tracts that allow them to better digest the carbohydrates in plants, says Barrows.
That’s why a typical salmon feed in 2010 was still 25 percent fishmeal (down from 35 percent in 2002) and a typical tilapia diet in 2010 was 3 percent (down from 5 percent in 2002), according to the International Fishmeal and Fish Oil Organization, the global trade association representing fishmeal and fish oil producers.
“It is difficult to identify any particular alternative ingredient ‘leading the pack,’” says Randy MacMillan, Clear Springs’ VP of research. “They all have potential at this time.”
Under lab conditions that MacMillan notes do not match the real world fish-production environment, trout fed a test diet with no fishmeal but which contained chicken meal, soybean meal and barley protein concentrate performed at an equivalent level to those fed a fishmeal diet, says MacMillan.
But — at least for trout — much testing work remains before the problem is solved, says MacMillan.
Contributing Editor Lisa Duchene lives in Bellefonte, Pa.