New feed means that salmon grow just as well and stay just as healthy, according to research by Linn Haug Eide.Tobias Torjusen / Nordforsk

Flies, poultry and fermented seeds act as feed

NORWAY
Wednesday, January 22, 2025, 06:50 (GMT + 9)

A groundbreaking study shows that black soldier flies, fermented sunflower seeds, and chicken meal are just as effective as traditional feed for salmon farming.

Salmon fed these alternative sources grow just as well, remain healthy, and gain the same weight per kilogram of feed.

"All our experiments consistently showed no negative effects," says Linn Haug Eide, an industrial Ph.D. candidate at Eide Fjordbruk. She conducts research in collaboration with her company and a university, focusing on topics vital to the industry.

Tackling Sustainability Goals

Eide's research targets sustainable feed solutions.

“The government has ambitious plans to increase salmon production, but sustainability challenges, particularly in feed, must be addressed,” says Margareth Øverland, a professor at the Norwegian University of Life Sciences (NMBU) and director of Foods of Norway. She also serves as Eide’s research supervisor.

Currently, 92% of salmon feed is imported, and feed production accounts for over 75% of the industry’s total carbon footprint. To address this, the Norwegian government has set a goal for all feed to be sustainable by 2034, with at least 25% produced locally.

Transforming Leftovers into Feed

Eide’s research explores three innovative feed options, all derived from by-products and food waste (known as "side streams"). These include:

1. Black Soldier Flies: Insects that convert inedible plants and food scraps into protein.
2. Fermented Plant By-Products: Plant residues with high fiber content are difficult for salmon to digest. Fermentation—used in making yogurt, soy sauce, and tofu—enhances flavor and nutrient availability.
3. Chicken Meal: By-products from chicken production, such as parts humans don’t consume, are processed into a nutritious feed ingredient.

Large-Scale Testing

"What sets this research apart is its scale," says Eide. Earlier studies on these feed types were limited to small laboratory settings. In contrast, this project tested the alternatives in fjord-based cages containing up to 50,000 salmon each, raising them to harvest size.

Linn Haug Eide has conducted a comprehensive large-scale study on alternative fish diets at Eide Fjordbruk, which operates 11 sea farming locations along Norway's west coast in Vestland County, spanning from the Hardangerfjord in the south to the Nordfjord in the north. Photo: NMBU/Eide Fjordbruk -->

Transparency in Research

A key aspect of the project was ensuring that findings are publicly available.

"Much feed research is conducted by private companies that keep their results confidential. Our aim is to benefit the entire industry. None of us plan to sell feed raw materials," Eide explains.

The research has already garnered significant attention. Articles have been published in international journals, and the use of fermented sunflower meal has been highlighted in the trade publication Feednavigator.

The feed has been tested on a full scale in the cages of Eide Fjordbruk. Tobias Torjusen / Nordforsk

Future Prospects

According to Øverland, European-produced sunflowers show promise for reducing dependency on imports. “The feed industry is shifting towards European sources. Companies are investing heavily in modern technology to ferment ingredients like sunflowers, soy, and corn,” she notes.

Eide adds, “Soy remains a staple in animal feed, but to ensure sustainability, we need diverse alternatives. My research has demonstrated that three of these options can meet the industry’s needs.”

Leading by Example

Eide Fjordbruk AS has already begun adopting these sustainable feed options.

“Feed is the largest contributor to the salmon industry’s carbon footprint,” says Erlend Eide, the company’s Technical Manager and head of research and development.

The company has long prioritized climate-conscious practices. "We were early in measuring CO₂ footprints and quickly realized the impact of feed. Our current focus is on reducing the carbon footprint and incorporating more local ingredients while maintaining fish health,” he explains.

Erlend emphasizes the need for further research. “Today, only a small fraction of salmon feed is locally sourced. Increasing this proportion requires innovation and investment.”

Source: Norwegian University of Life Sciences (NMBU)

Linn Haug Eide will defend her doctoral thesis at NMBU on January 29th.

Title of the thesis: "Alternative Protein Sources for Farmed Atlantic Salmon Evaluated Under Commercial-Scale Field Conditions"

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