Some producers have reported reduced pigmentation in 20-40% of their stock in recent years.
Nofima, the Norwegian food research institute, has conducted a detailed analysis on the pigmentation of salmon fillets among Norwegian fish farmers, identifying several factors affecting fillet coloration and proposing potential solutions.
Funded by the Norwegian Seafood Research Fund (FHF), the study was spearheaded by senior researcher Trine Ytrestøyl and her team. It involved surveys from industry stakeholders in 2023, data on fillet color from commercial productions between 2012 and 2023, and findings from Nofima’s research licenses.
Key Findings
The study unearthed a previously undocumented negative impact of frequent mechanical delousing on fillet color. This could be attributed to increased consumption of the antioxidant astaxanthin when fish are stressed, or reduced feed intake leading to lower slaughter weights, both of which affect fillet pigmentation.
“There is significant correlation between the survey responses from fish farmers and our data analysis, suggesting a realistic depiction of the current situation,” said Ytrestøyl.
Variable Extent of Pigmentation Issues
The extent of pigmentation problems varies among farmers. While some report reduced pigmentation in as little as 2% of their fish, others face issues in 20-40% of their stock. Standards for acceptable color intensity also vary, with targets ranging from 24 to 27 on the SalmoFan scale and 5 to 7 milligrams of astaxanthin per kilogram of fillet.
Historical data indicates a decline in color intensity from 2012 to 2021, with slight improvement thereafter. This variation aligns with survey findings that some farmers struggle more with pigmentation issues than others.
Measures and Planning
Most respondents have implemented measures to enhance pigmentation, such as increasing astaxanthin in feed (50-70 mg per kg) and adding more omega-3 fatty acids and vitamins. While these measures have been effective, they come at a high cost.
Ytrestøyl noted that “rapid growth resulted in poorer pigmentation, while color improved with increasing slaughter weight.” The study also confirmed the detrimental impact of multiple mechanical delousing treatments.
One unexpected finding was the significant color variation at harvest between different smolt suppliers, prompting further investigation into the influence of the smolt phase on pigmentation levels.
Strategic Insights
The study provides a wealth of data for fish farmers to consider. Full details can be found in the report available on the FHF project website.
As the aquaculture industry continues to expand, understanding and addressing these pigmentation challenges will be crucial for maintaining the quality and marketability of Norwegian farmed salmon.
