Press Room
Harvest timing and processing duration affect Atlantic salmon fillet colour
St. Andrews, New Brunswick, Canada – April 1, 2026
Atlantic salmon fillet colour can be influenced by diet and genetics while playing an important role in consumer purchasing decisions. The reddish colour of salmon fillets comes from the binding of naturally occurring unmetabolized carotenoid pigments, such as astaxanthin and canthaxanthin, to the muscle – which is the same process that gives the pink to reddish-orange feathers of a flamingo! Adding natural astaxanthin to the salmon diet is now a common practice but at considerable expense as it accounts for 5-10% of total feed cost. It is therefore important to understand the effect of fish and family genetics for those able to deposit and retain more of the pigmentation in their muscle to give favorable fillet colour.
Earlier published data from The Huntsman Marine Science Centre (St. Andrews, NB) reported that fillet colour was a highly heritable trait amongst salmon families. However, colour intensity and variability are known to be influenced by many factors. Breeding programs rely on accurate measurements when describing a specific trait, such as measured during commercial harvest evaluations, to make informed breeding decisions. Any effect of small time discrepancies over hours to days on muscle colour intensity has received limited research attention. However, these effects could impact the perceived quality of fish and may alter accurate estimation of breeding values for selection.
“We had a unique opportunity to collect detailed data on thousands of individual fish over many years of production during commercial scale harvest evaluations,” explained Dr. Amber Garber, Huntsman Marine Research Scientist and anchor author of the recent publication in the international peer-reviewed journal Aquaculture. “Our detailed dataset gives us the ability to assess how quality traits, like fillet colour, are affected by harvesting and processing time to increase confidence in our selection decision making process.”
Huntsman Marine researchers recently published results from 10,380 individual Atlantic salmon fillets that were collected over eight year classes from 2011 to 2019. All collected data was time stamped to evaluate the impact of harvest day, hour of the day, and processing duration from the time between entering the plant facility to assessing fillet colour. Fillet colour was assessed both visually by comparing it to a standard swatch called a SalmoFan and measuring the colour components of redness, yellowness and lightness using a Minolta Chroma Meter.
Harvesting all fish from a sea cage may occur in two or three separate harvest events in order to adequately provide workers sufficient time to process fish. The environmental conditions and feeding regimen experienced by the salmon remaining within the cage may differ dramatically as the total harvest proceeds. Not being fed again before harvested or experiencing stress during previous removals of fish may also affect fillet quality and color once remaining fish are eventually harvested. The 2015 year class fish had the largest span of days between first and last harvest and also experienced the greatest effect of days for the harvest on colour with generally lighter fillets as days increased.
“It is reasonable for about three days to pass for gutting, rigour mortis and then filleting harvested Atlantic salmon for fillet colour assessment to occur and ideally each fish would be processed in the same amount of time,” noted Garber. “Only our 2017 year class involved a single harvest day so that all plant activities were completed for the entire assessed group at the same time and, as expected, these salmon fillets were not influenced by time.”
Some fish in the study were assessed for colour up to 46 h after these same measurements were completed for other fish. Generally, the data showed that longer times to complete the processing requirements resulted in fillets that were lighter in colour. Processors recognize that the way salmon are stored and filleted post-mortem may affect fillet colour and the data published here further confirms this notion.
SalmoFan scoring was the only colour measurement that was significantly affected by time of day with lower values assigned later in the day. All SalmoFan assessments were completed by the same individual but this is a subjective measurement and may be influenced by eye fatigue or general weariness as the evaluation day progresses. Correcting the SalmoFan scores to account for the hour of the day increased its correlation with Chroma Meter colour component measurements.
All measured colour traits from each year class had moderate to high heritability ranging from 0.260 to 0.859 when days of harvest, duration of processing and hour of the day were not accounted for in the models. These heritability estimates increased to be within a range from 0.286 to 0.860 when these time components were included in the statistical model. Fillet lightness and SalmoFan values showed the largest changes in most year classes when timing effects were included in the analysis.
It is important to include a time stamp when collecting data as without these considerations certain fish may be erroneously perceived to have a higher value relative to other individuals thereby skewing overall trait heritability and selection. Completing full harvest evaluations in as few days possible is important to ensure the most appropriate comparison of results across individual fish and families as well as amongst year classes in a commercial breeding program. The published results may also have broad applicability to general product quality and marketing of farmed Atlantic salmon.
“Our published results demonstrate the effect of days of harvest, duration of processing, and hour of the day on heritability and fillet colour Estimated Breeding Values,” concluded Garber. “It is essential that we time stamp data collection when evaluating colour traits, and possibly other quality traits, to make unbiased breeding decisions and apply genomic selection analysis.”
The publication was co-authored by researchers at Mowi Genetics AS (Bergen, Norway). The study was funded by the Atlantic Canada Opportunities Agency (ACOA) Atlantic Innovation Fund, New Brunswick Innovation Foundation (NBIF) Research Innovation Fund, Genome Canada & Genome Atlantic, and industry partners.
Research Publication:
Langille, B.L., P. Sae-Lim, S. Boison, P.G. Wiper and A.F. Garber. 2025. Duration, day, and hour postmortem influence the color of farmed Atlantic salmon: Insights into phenotypic measurements. Aquaculture 596: 741739. https://doi.org/10.1016/j.aquaculture.2024.741739.
Image 1: Quantifying attributes of colour using a Minolta Chroma Meter versus the subjective method comparing fillet colour to a SalmoFan.
Image 2: Huntsman Marine staff completing a commercial Atlantic salmon harvest evaluation.