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TWIN FALLS • In a world where the population is growing rapidly, food security is increasingly dependent on a species that never walks on land.

“Around the world, farms are raising more fish than beef,” said Jesse Trushenski, a fish nutritionist at Southern Illinois University. And that trend has to continue to feed a growing global population.

While researchers estimate overall world food production needs to increase by 2050 to feed a projected 9.5 billion people; the world will need more animal protein much sooner. Experts are now estimating the world will need 60 percent more animal protein by 2030 to meet the growing demand of an increasing global middle class. China, for example, increased from eating nearly no seafood in 1940 to consuming nearly 90 pounds per person by 2006. In contrast, the average American consumed about 16.5 pounds of seafood that year.

In 2011, the world consumed 137.5 million tons of fish with nearly 68 million tons coming from aquaculture. To increase production by 50 percent in the next 10 years, feed manufacturers will need to increase global fish feed production to about 50 million tons and use about 33 million tons of protein products.

Given that the world produces only about 6.5 million tons of fish meal, most of that protein will need to come from other sources.

Globally, aquaculture consumes two-thirds of the world’s fish meal and three-fourths of the fish oil supply. Even though research at the University of Idaho and other institutions have identified plant-based alternatives that have allowed manufacturers to reduce the level of fish meal from 45 percent to around 22 percent and replace up to half of fish oil in a ration, fish-based ingredients will always be used by aquaculture.

That’s because fish require more protein than traditional livestock and fish-based byproducts are protein-dense. Even an omnivore like tilapia, which eats both plants and animals, requires at least 30 percent of its diet to come from protein. Beef cattle, in comparison, typically require 15 to 20 percent.

Mid-level carnivores such as rainbow trout and salmon require 40 to 45 percent protein in their diets but 50 to 60 percent of the salmon carcass is edible. Only about two-fifths of a steer carcass is consumed by humans.

Fish are also more efficient at converting that protein into filets than cattle are at turning into steaks. Grass-fed beef require 8 pounds of feed for every 1 pound of weight they gain. Pork and poultry are more efficient with feed conversion rates of 3-to-1 and 2-to-1, respectively. But only fish, who don’t need to burn energy to regulate their body temperature, can turn 1 or 1.5 pounds of feed into a pound of gain.

“Aquaculture does more with less,” she said.

University of Idaho researchers are playing an important role in helping aquaculture become both more productive and sustainable. Identifying plant-based alternatives to fish meal and oil, and then developing diets to utilize those new ingredients has been critical. But the greatest breakthroughs have come as a result of identifying fish that can utilize those new alternatives.

“Feed formulations are easy to change on the computer but it is not easy to formulate such feeds and maintain high fish performance,” explained Ron Hardy, head of the UI Fish Culture Experiment Station at Hagerman.

The trout selective breeding program began in 2000 with eight trout strains. Selection is based on fish performance when fed an all-plant protein diet.

Each generation of the new rainbow trout species has shown a 10 to 15 percent increase in growth, Hardy said. By the sixth generation (each fish generation is two years), all the family lines were growing faster on an all-plant protein diet than on the fish meal control diet. These trout lines are also more disease resistant than commercial fish.

“With the selection trout, we have fish that possess the ability to tolerate high soy diets,” Hardy said, adding that those are the diets of the future.

“Sustainability isn’t about getting away from using fish meal and fish oil, it’s about using it wisely,” Trushenski said.