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Using salmon to feed other salmon would be great for the environment 

We eat fish for its rich protein, which drives several vital processes in the human body. Fish protein is also important for other fishes. That is why fish are fed with whole fishes and fish protein as part of their diet. But away from predation, researchers now suggest that feeding fish, particularly salmon to feed salmon, with other salmon can make them more environmentally friendly.

Eco-friendly fish farming

Researchers may have found a way to make fish farming more environmentally friendly by feeding fishes with other fishes.

According to a study conducted by researchers at the Norwegian University of Science and Technology (NTNU), Norway, salmon fed with other salmon exhibited eco-friendly characteristics.

These salmon recorded a lower carbon footprint and required less energy for reproduction when compared to the salmon fed with other types of fish.

The experimental process

The researchers conducted a feeding trial using Atlantic salmon (Salmo salar). They fed fish with diets containing various amounts of dried salmon protein hydrolysate (FPH) and fish meal protein.

Salmon hydrolysate is a product of the enzymatic breakdown of the leftover raw materials from salmon processing. Hydrolysate is an excellent fish meal because it is easily digestible and tastes good. This encourages the fish to eat more. 

Feeding salmon to salmon – is this cannibalism?

Fish of the same species feeding on each other is cannibalism. However, this is not the case with the salmon in this study. That is because the dead salmon have been processed into protein hydrolysate before feeding them to the living fish.

“You might think this is cannibalism. It’s not, however, because the proteins have been broken down so much that their origin is not recognizable without conducting DNA analyses,” explained study lead author Ingrid Schafroth Sandbakken.

The predatory nature of salmon means they are comfortable feeding on their species. “They only distinguish between what fits into their mouth and what doesn’t,” she added.

Are there any risks?

Interestingly, fish farmers have expressed skepticism about the idea of feeding salmon with salmon. They argued that there might be a risk for prion disease and similar concerns.

Prion disease is a rare but fatal disease that has been established in mammals, including humans, but not in fish or birds. 

However, the researchers checked for prions in the salmon hydrolysate using two different methods and found none.

“No prions have been found in the salmon hydrolysate. Even if we had found prions, there is nothing to suggest that prions from fish cause disease in humans since there is a species barrier for such diseases,” the researchers noted.

What does this mean for fish farming?

A large amount of the climate footprint of the aquaculture industry is linked to feed ingredients and production. Feeding salmon with salmon protein hydrolysate instead of regular fish feed can help reduce this.

Switching to residual raw fish feed materials ensures local and sustainable production. It also removes the pressure on plants, which currently serve as the primary source of salmon feed.

More about salmon

Salmon, famous fish that is the focal point of this article, is the shining star of both freshwater and oceanic habitats. It captivates many with its beauty, strength, and delectable taste. Hailing from the family Salmonidae, these fish play a significant role not only in our diets but also in their ecosystems.

Life cycle and migration

Salmon begin their life in freshwater. They hatch from eggs in rivers and streams, emerging as tiny fry. These fry grow into smolt, which is when they prepare to make their journey to the ocean. This transformation, called smoltification, readies the young salmon for life in saltwater.

Upon reaching maturity in the ocean, a deep-rooted instinct prompts them to embark on an impressive journey back to their birthplace to spawn. They navigate with pinpoint accuracy, using the Earth’s magnetic field and their keen sense of smell. Once they reach their natal streams, females lay thousands of eggs in gravel nests called “redds,” which males then fertilize. After spawning, many salmon species die, but their sacrifices ensure the continuation of the next generation.

Physical attributes

Salmon exhibit a wide range of colors, from silver-blue hues when living in the ocean to brilliant shades of reds, oranges, and purples during their spawning phase. They have a streamlined body built for efficient swimming, and their powerful tails help them leap over obstacles and against currents.

Dietary value

Salmon ranks high among health enthusiasts. It’s a rich source of omega-3 fatty acids, which benefit heart health and brain function. Additionally, salmon offers a good amount of protein, B vitamins, and various minerals like potassium and selenium.

Threats and conservation

Overfishing and habitat destruction threaten salmon populations worldwide. Dams hinder their migration routes, and pollution degrades their spawning grounds. Conservationists work tirelessly to restore habitats, advocate for sustainable fishing practices, and introduce fish ladders at dams to aid salmon migration.

In summary, salmon are not just a culinary delight; they are marvels of nature with intriguing life cycles and vital roles in their ecosystems. As we enjoy their taste and benefit from their nutrients, it’s essential to recognize our responsibility to protect these incredible fish and ensure their populations thrive for generations to come.

This study is published in the journal Aquaculture.

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