The goal is that Norwegian fish farming should increase fivefold by 2050 and use at least 25% Norwegian-produced feed ingredients by 2034

Aquaculture Innovation: Mueller's Pearlside Poised to Revolutionize Norwegian Salmon Feed

NORWAY
Wednesday, June 25, 2025, 00:10 (GMT + 9)

New Study Shows Deep-Sea Fish Boosts Growth and Improves Gut Health in Farmed Salmon, Key for Sustainability and Self-Sufficiency Goals

In a significant breakthrough for aquaculture, a recent Nofima study has revealed that including protein from Mueller's pearlside, a small mesopelagic fish, in farmed salmon feed not only maintains excellent growth but also remarkably improves gut health. This finding is crucial for Norway, which aims to quintuple its aquaculture production by 2050 and source at least 25% of its feed ingredients domestically by 2034.

Procesamiento de peces mesopelágicos en planta piloto en el Centro de Tecnología de Alimentos Acuícolas de Nofima (ATC, Bergen). Foto: Albrektsen/Nofima.

The ambition to reach five million metric tons of Norwegian salmon by 2050 faces a primary bottleneck: feed. Currently, a large portion of ingredients are imported, often competing with human food production and raising sustainability concerns. The search for local, low-trophic sources, such as Mueller's pearlside—abundant in the deep waters near the Norwegian coast—has become imperative.

Surprising Results from Feed Trial

The study, conducted by Nofima at its Bergen center, utilized feed produced from Mueller's pearlside meal and silage. Atlantic salmon were fed five different diets at Nofima's land-based research facility in Sunndalsøra, comparing them to a control group receiving standard feed with blue whiting meal.

Despite an initial digestibility test in mink (NMBU) showing that the mesopelagic pearlside protein had slightly lower digestibility (85% vs 90%), this did not negatively impact the fish. "We saw almost a fourfold increase in growth. Especially in the first phase, the fish grew very well," states Sissel Albrektsen, a senior researcher at Nofima. "We observed no difference in growth across any of the groups, nor in feed intake or feed utilization. These groups were completely identical, which was a bit surprising for us since the control feed had better protein digestibility."

Beyond robust growth—so good that the trial had to be concluded a week ahead of its scheduled 12 weeks—fish from all diet groups showed similar protein, fat, and ash content, with no differences in enzymes, fatty acids, immune parameters, or various stress markers.

Maurolicus muelleri, comúnmente conocida como bacaladilla de Mueller (izquierda). En el Centro de Tecnología de Alimentos Acuícolas, NOFIMA prueba nuevos ingredientes y desarrolla alimentos del futuro (derecha). Foto: Helge Skodvin/Nofima

Improved Gut Health: The Major Benefit

One area where Mueller's pearlside demonstrated a clear advantage was in the salmon's ability to transport fat from the intestine into the rest of the body. Researchers observed that the control group, fed blue whiting, developed a condition called enterocytic steatosis, an accumulation of fat in the intestinal epithelium. However, this accumulation was almost non-existent in fish that received feed based on Mueller's pearlside.

"When we use only mesopelagic fishmeal, without the control meal, we do not see fat accumulation in the intestine," explains Albrektsen. "There is something in the mesopelagic raw material that makes the transportation of fat into the rest of the body function as it should. It is clear that the blue whiting diet lacks something that is present in the mesopelagic fishmeal." This could be linked to the high natural levels of choline in Mueller's pearlside fat.

Los peces se dividieron en cinco grupos. Uno recibió una dieta de control a base de bacaladilla y los otros cuatro recibieron dietas con bacaladilla de Mueller.

While the fat accumulation in the control group was not severe, the ability of Mueller's pearlside-based feed to prevent it is considered a highly positive result. Mueller's pearlside silage also slightly outperformed the control diet in terms of gut health, although the mesopelagic meal yielded even better results.

"The main conclusion is that the mesopelagic raw material, both in the form of meal and concentrate (silage), provides very good results in feed intake and growth in salmon compared to fish receiving a high-quality control diet that includes blue whiting. It counteracts fat accumulation in the mid-intestine, and we believe this is related to the naturally high level of choline in the mesopelagic fat," Albrektsen concludes.

This study underscores the potential of Mueller's pearlside to significantly contribute to Norway's aquaculture sustainability and self-sufficiency goals, opening new avenues for local and low-impact feed production.

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