Research on aquatic animal nutrition at the University of Idaho is revealing better ways to raise fish while focusing on sustainability, cost effectiveness & environmental safety.
Aquaculture is the world’s fastest growing agriculture industry and has provided the majority of human-consumed fish since 2016, according to the Food and Agriculture Organization of the United Nations, and Idaho is the largest producer of commercial rainbow trout in the U.S. UI’s Aquaculture Research Institute (ARI) is charged with finding ways to improve the industry.
One problem the Idaho aquaculture industry faces is the presence of excess iron in the groundwater, Assistant Professor Vikas Kumar said.
In one of ARI’s many projects, Kumar published research last Wednesday studying the mitigation of iron toxicity in catfish. Working in collaboration with the University of Arkansas, the team found feeding catfish vitamin C can alleviate the negative effects of too much iron in the water.
“We cannot buy the filter (to remove the iron) because if we were to buy the filter to grow fish, we would spend millions of dollars to clean the water,” Kumar said. “That’s almost impossible. So, what we did is ask what we could do to the nutrition (of the fish).”
Kumar and his fellow researchers found feeding trout bentonite, a type of natural clay, relieved stunted growth caused by iron toxicity. Kumar said the bentonite binds with the iron molecules, making it indigestible, and it is discarded in the fish waste.
Other ways to increase sustainable growth in fish include changing their diets from primarily fish meal to plant-based food. ARI has made efforts to breed rainbow trout, a naturally carnivorous species, which can stay healthy while fed a plant-based diet. Matt Powell, another associate professor at UI, works with fish nutrition at ARI’s station in Hagerman, Idaho.
“We have essentially turned a carnivorous fish into a vegetarian fish,” Powell said. “It helps with the sustainability of growing fish and the sustainability of aquaculture. It has less of an impact on the ocean environment because we can utilize things like soybean meal, wheat and other types of plant protein.”
Despite the positive impacts, feeding carnivorous animals plants doesn’t come without its issues. Fish react differently to plant proteins than they do to animal proteins. Powell’s research looks into how to make plant proteins digestible to carnivores, then selectively breed the fish which react to the diet well, creating a variety of fish which can survive only on greens.
ARI works with rainbow trout most, but Powell said the institute has also done nutritional and genetic analysis of endangered species and collaborated with several organizations to find ways to bring them back.
Brian Small, director of ARI, said the Columbia River Inter-Tribal Fish Commission (CRITFC), which consists of four Native American tribes, collaborated with the institute to study the production and recovery of steelhead, salmon and other local species of fish.
Kenneth Cain, associate director of ARI, works with the Kootenai Valley Resource Initiative to help reestablish the population of burbot, a type of freshwater cod with cultural significance to the Kootenai Tribe.
“So we do a lot more than just foo fish,” Small said. “We do a lot with the fisheries, the wild fishery side of it as well. We’ve had some really good interaction with the tribes that really rely on the native fishery resources.”
Anteia McCollum can be reached at email@example.com or on Twitter @antxiam5.