Quality is paramount for salmon consumers, and buyers discern with their eyes. Consistent color and lack of dark spots are indicators of quality, and seafood consumers look for both in selecting the best fillets.
To produce these desirable qualities, salmon must eat nutritious diets, rich in omega-3 fatty acids, including DHA and EPA, which have previously been sourced from wild fish. However, fish oil supply is declining as wild populations are impacted by environmental pressures. The aquaculture industry has replaced some fish oils with vegetable oils which lack these essential omega-3s. New omega-3 sources are needed to support fish health. Numerous studies recognize Aquaterra® oil, derived from Nuseed Omega-3 Canola, is a safe and effective source of long-chain omega-3 fatty acids.
To better understand how alternative sources of omega-3 impact fillet quality, the Norwegian Institute of Food, Fisheries and Aquaculture Research (NOFIMA) conducted a study, “Improved fillet quality in harvest-size Atlantic salmon fed high n-3 canola oil as a DHA-source,”* examining the “long-term effects on performance and fillet quality under realistic farming conditions.”
The study sought to identify whether fish feeds containing Aquaterra Advanced Omega-3 oil produced a measurable improvement in salmon fillet quality.
Farmed Atlantic salmon raised in seawater cages, were divided into three groups which received diets containing a varying amount of Aquaterra Advanced Omega-3 canola oil. These diets, labeled as Standard, Medium, and High, included the following levels of DHA and DHA + EPA:
- Standard: 1.49% DHA and 2.36% total DHA + EPA
- Medium: 2.40% DHA and 3.30% total DHA + EPA
- High: 2.84% DHA and 3.71%% total DHA + EPA
The farmed salmon were fed their assigned diets for a period of one year, to an average harvest weight of 4.7 kilograms.
Researchers found that fish fed greater amounts of Aquaterra Advanced Omega-3 canola oil had correspondingly higher amounts of ALA and DHA in their tissues and higher quality fillets.
The amount of dietary omega-3 canola oil had no impact on salmon growth or mortality, which is in line with accepted understanding that it is a safe and effective source of omega-3 fatty acids.
Unsurprisingly, the more total omega-3 in the fish feed, the more of these fatty acids were found in body tissues. The average relative amount of total omega-3 found in the muscle tissues for fish fed each of the standard versus high diets was:
- Standard: 7.7% ALA, 2.2% EPA, and 5.2% DHA
- Medium: 10.5% ALA, 2.4% EPA, and 8.1% DHA
- High: 12.3% ALA, 2.5% EPA, and 9.8% DHA
Importantly, the total content of omega-6 fatty acids—associated with increased inflammatory response—declined as the amount of dietary omega-3 fatty acids rose. This improved ratio of omega-6:omega-3, and increased overall total content of omega-3 fatty acids, is understood to be beneficial to human nutrition.
Researchers also looked at the impact of omega-3 canola oil in fish feed on the aesthetic quality of the resulting fillets. The amount of Aquaterra omega-3 canola oil used in fish feed did not have a significant effect on fillet firmness. However, omega-3 intake had a profound impact on presence of melanized dark spots in the muscle tissue of the salmon. In the standard group, 31% of fish had dark spots, a notably larger proportion than in the medium and high groups. Muscle tissue from the medium group had the fewest dark spots (9%), while 20% of the high group had dark spots.
Fish fed the medium or high diets had muscle pigmentation that scored higher for redness, yellowness, and chroma, and overall had improved coloration.
This study is one of several studies showing that not only is Aquaterra Advanced Omega-3 canola oil an effective source of omega-3 fatty acids, but also that it increases quality and nutrition. Aquaterra is more than a sustainable alternative to scarce marine oils, it is a true advancement in omega-3 nutrition and fish quality.
*Citation:
Hatlen et al. (2022), Improved fillet quality in harvest-size Atlantic salmon fed high n-3 canola oil as a DHA-source. Aquaculture. DOI: https://doi.org/10.1016/j.aquaculture.2022.738555