Researchers in Baltimore have perfected a fish food recipe that can turn tasty marine carnivores into vegans. The team’s findings are published in the August issue of the journal Lipids.
Fishless Fish Food
For years, scientists have been cooking up combinations of plant-derived nutrients to replace wild-caught species used to fatten high-demand predators sold in supermarkets.
Nearly half of the world’s fish and seafood is raised in captivity instead of caught in the wild. Aquaculture has the potential to take pressure off of depleted fisheries, but not when farms still depend on fishmeal from wild sources like Atlantic menhaden, sardines and anchovies.
With seafood demand increasing and the world population ballooning, researchers want to find ways to keep up in a sustainable way.
Aaron Watson and Allen Place from the University of Maryland Center for Environmental Science fed the predators a stew of soybean or canola oil, lipids from algae, and amino acid supplements such as taurine. For each species studied, the food needed to match up with the animals’ natural enzymes. It took the team four years to get it just right.
It turns out that so-called black salmon, or cobia — a fillet fish popular in Europe and Asia that’s gaining ground in the U.S. — don’t like barley or wheat gluten. The fish-food chefs based their recipe on diets used for rainbow trout developed by co-author Frederic Barrows at the U.S. Department of Agriculture in Montana.
“We can reduce fishing pressure on both of the populations of species that we catch directly for human consumption and these species that are caught for fish meal and fish oil for the aquaculture and agriculture industry,” Watson said. He added that researchers around the world are looking for ways to turn alternatives like biofuel waste, fish processing scraps and invasive species into sustainable fish food.
“We’re finding ways to turn these plant resources that the United States has in abundance and turn it into meat.”
Tide Of Progress
The National Oceanic and Atmospheric Administration and the Department of Agriculture has been pushing research on alternatives to support aquaculture since at least 2007.
Michael Rust, science coordinator at NOAA’s Office of Aquaculture, says the aquaculture industry has already been weaning itself off of fish meal and fish oil for years, and its use in aquaculture peaked in 2006.
“As aquaculture is increasing, the amount of fishmeal going into it is decreasing. I think we’ll continue to see that trend,” he said.
“The whole idea that fish meal and fish oil is required for carnivorous fish is one that’s scientifically not valid. There is no nutritional requirement. We’ve known for a long time that you can feed them other things, but it’s taken a while for the economics to catch up and actually put that into practice.”
Rust said the findings in Maryland are encouraging, but downplayed the impact of a single breakthrough.
“Science is a lot more like slow, plodding Clydesdales all pulling against the same heavy load, versus thoroughbreds that are out there winning races.”
- Baltimore Researchers Turn Carnivorous Fish Into Vegetarians (Washington Post)
- New “Fishless” Feeds Could Make Aquaculture More Sustainable (Gizmag)
- Where Have All The Menhaden Gone (East End Beacon)