I have an opportunity to work as an engineer for the wastewater division of a construction firm. Their current project is expanding an aquaculture farm that grows fish. From what I can tell, this client is one of the best in terms of sustainability. They are using a RAS with 5:95 fish to water ratio and 99% recycled/filtered water; claim to be parasite free, use no hormones/antibiotics and have no escapees; purchase the best quality feed on the market, from a company that is working to eliminate fish from the feed; and are close to being carbon neutral.
However, they are not transparent about their harvesting practices; fish can be expected to develop different behaviors over time when not raised in the wild; water is drawn from an aquifer near the coast, so there's the risk of over-pumping and saltwater intrusion; and much of the waste likely still ends up in the ocean.
While ideally, our oceans would be healthy, we would fish wild salmon and wouldn't over-fish (or not fish at all), I'm looking for a realistic approach. If this company can show that it's practices are healthier and more profitable, it may convince worse companies to adopt better practices. I'm curious what some professional opinions are, from an environmental science perspective.
https://www.sciencedirect.com/science/article/pii/S0308814621024511
Highlights • The nutrient composition of farmed salmon has changed over the past 15 years.
• The contents of EPA + DHA in farmed salmon have decreased by > 60% from 2005 to 2020.
• One portion of farmed salmon (175 g) still meets weekly recommendations of EPA + DHA for adults.
• One portion of farmed salmon provides > 100% of the RI of vitamin D for adults.
• Farmed salmon can contribute considerably with several key nutrients.
Abstract The changes in the feed of farmed Atlantic salmon (Salmo salar) towards a more plant-based diet affect the nutritional value of the fillets. By compiling the contents of a range of nutrients in 1108 samples of Norwegian farmed Atlantic salmon collected between 2005 and 2020, we found that the median contents of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) have decreased by > 60%. However, farmed Atlantic salmon remains a considerable source of EPA and DHA, with one and two portions being sufficient to meet the weekly adequate intake of EPA and DHA for adults (175 g) and two-year-olds (80 g), respectively. Farmed Atlantic salmon also remains a considerable source of protein, selenium, vitamin B12, and vitamin D3. Together, we demonstrate that farmed Atlantic salmon can contribute substantially to the nutrient intake of the consumers. These data are important for the Norwegian food composition table and future risk–benefit assessments on fatty fish consumption.
