Stephanie Colombo

Salmon species matter when it comes to fish on your plate

First of its kind study in Canada shows species of salmon makes the biggest difference in nutritional quality — not whether it was farm raised or wild caught

By SeaWestNews

Farmed Atlantic salmon are among the best options available when it comes the nutritional quality of salmon in Canada, a new study by researchers at Dalhousie University has found.

The study published in the Journal of Agriculture and Food Research found farmed Atlantic and farmed organic Atlantic salmon had the lowest amounts of mercury, with relatively high omega-3 when compared to wild Pacific salmon.

There are mixed messages when it comes to farmed salmon, with some people believing it may contain contaminants and is not as nutritious as wild-caught fish, Dr. Stefanie Colombo, an assistant professor of Aquaculture at Dalhousie University’s Agriculture Campus told Dalhousie News.

“I get a lot of questions from people I meet about farmed salmon and many people have the idea that it’s not good for you, that it’s full of fat and contaminants,” said Dr. Colombo, who also holds the Canada Research Chair in Aquaculture Nutrition.

“I knew these were misconceptions, but I wanted to know how it compared to the other types of salmon that were out there.

“I was surprised by a few things. It’s really the species of salmon that makes the biggest difference in nutritional quality — not whether it was farm raised or wild caught, or whether it’s certified organic or environmentally certified. For example, there was a big difference in the wild salmon we looked at — between Sockeye, Chinook and Pacific.”

The aim of the study was to demonstrate differences among salmon types, rather than simply comparing differences between wild vs. farmed.

According to the findings of this study, the wild Pacific salmon type was found to be the least nutritionally-dense (due to high water content), followed by the farmed organic Chinook salmon (nutritious, but relatively high mercury content compared to other options).

Wild Sockeye, wild Chinook, farmed Atlantic, and farmed Atlantic organic were found to be the best options.

Wild Sockeye had the highest n-3 LC-PUFA amounts per serving and highest protein (on a wet weight basis). However, farmed Atlantic and farmed organic Atlantic salmon had the lowest amounts of mercury, with relatively high omega-3 LC-PUFA amounts. Considering nutrient density, EPA+DHA content, and mercury content, Sockeye, Chinook, and Atlantic salmon are excellent options.

The study involved purchasing six different types of salmon that are commonly available to Canadians to compare the nutritional information for each type, focussing in particular on the omega-3s. The fish included were farmed Atlantic, farmed organic Atlantic, farmed organic Chinook, wild Chinook, wild Pacific pink and wild Sockeye.

The team brought all the samples to the Dal Agricultural Campus in Truro, processed the fillets and did various nutritional analyses, as well as for mercury. Dr. Colombo tested the different salmon species that were either wild, farmed, organic, non-organic, environmental certified, and non-environmental certified.

Dr. Colombo found that the more expensive wild Sockeye, which can be $31.50/lb, and wild Chinook had the most nutrient-dense and highest omega-3 content. But she also discovered that farmed Atlantic salmon, which costs about $12.50/lb, had the lowest mercury content, had a high nutrient density, is more affordable and available on both of Canada’s coasts.

“There’s actually no other study out there that has done this for Canadian salmon,” she said. “There have been studies that focus on the contaminants, but they are several years old and things have changed in the environment and in aquaculture. So, it was an exciting opportunity to do an investigation.”

Dr. Colombo said the material can be useful for consumers searching for nutrition information about salmon, while clearing up confusion about distinctions between wild and farmed fish.

Based on these results, Sockeye and Chinook can be consumed less frequently for the same nutritional value. However, they are expensive and there are limits on sustainable catch levels. But if you enjoy eating salmon more frequently, Dr. Colombo said farmed Atlantic is a great option for its nutritional value, cost, availability and low mercury.

Aquaculture supplies around 50 per cent of the world’s fish for human consumption, with Canada being the fourth largest producer of salmon in the world, behind Norway, Chile and the United Kingdom. The volume of farmed Atlantic salmon has increased by 800 per cent since 1990, with 72 per cent of salmon we eat today being farm-raised, according to the paper.

The research, which was funded by a Discovery Grant from the Natural Science and Engineering Research Council of Canada (NSERC), may also provide policy makers with important information on the nutritional value and possible future labelling for a fish that is linked to improved cardiovascular and neurological health, the development of visual capabilities and brain development in fetuses, and has anti-inflammatory properties.

Further, research investigating a more extensive nutritional profile from other sources of salmon globally would provide a more global context, the study concluded

“Ultimately, the goal is to have safe and nutritious salmon available to Canadians, in a sustainable manner,” said Dr. Colombo.

(Image courtesy of Dalhousie University shows Dr. Stefanie Colombo)