By Taylor Walker, BHSc MDietSt Student (UQ)
According to Australia’s Sustainable Seafood Guide farmed Atlantic salmon is the highest value and volume fisheries product from Australia.
Salmon is clearly a popular choice, and two thirds of the global supply of salmon is farm-raised, but which variety is better, farmed raised or wild? The question “Which is better?” begs the follow up question “Better how?”; better for health, better for the environment or the better bargain?
Two of the most commonly mentioned factors that differ between wild caught and farmed salmon are the overall health benefits for consumers, and the environmental impact and sustainability of production. The potential reasons for consumers to choose between wild and farmed salmon for their Friday night fish and chips are multifaceted and perhaps tricky to analyse, so let’s break it down scale by scale.
When discussing the health benefits of eating salmon, “omega-3’s and essential fatty acids” is catch-phrase number one. EPA and DHA are two Omega-3 long chain polyunsaturated fatty acids (PUFA) that are shown to be important for development, disease and healthy ageing. Omega-6 PUFAs are also essential fatty acids, however, are required to be carefully balanced with Omega-3s for optimal benefit. Both the wild and farmed varieties contain high concentrations of omega 3 but there are substantial differences in omega 6 content. Farmed salmon has approximately 4 times higher levels of omega 6 fatty acids compared to wild salmon. While the balance between omega 6 to omega 3 is less optimal in farmed salmon this is still unlikely to be of concern.
Catch phrase number two when discussing salmon is “what about contaminant levels”. Testing has shown accumulation of organic contaminants in the flesh of both farm-raised and wild caught salmon, which can be associated with adverse health effects. Polychlorinated biphenyls (PCBs), dioxins and dioxin-like compounds (DLCs) are commonly found in higher levels in farmed salmon than that of wild-caught, and are known to be related to cancer in humans. However, salmon farmed in different areas including Northern Europe, North America and Chile have different contaminant levels. Salmon sourced from Northern Europe (where Australia imports part of its farmed salmon stock from) contained the highest levels of DLC’s; however, these levels are still within internationally recognised safety limits. Conservative estimates of a safe level of consumption of farmed salmon are still above current Australian guidelines for fish consumption.
Sustainability of fish stocks, as well as pollution are controversial concerns in the seafood industry, with wild caught and farmed salmon both contributing pros and cons. As the name suggests, wild-caught salmon are sourced from their natural environment in oceans, rivers and lakes. Farmed Atlantic salmon are farmed in open water cages in the ocean, creating a semi-natural living environment for the fish, but also potentially disturbing the natural ecosystem of the water and seabed below the man-made cages. Although farmed salmon assist in not contributing to over-fishing and depletion of wild fish stocks, the land/sea area negatively impacted by the production is a point of concern. At Macquarie Harbour in Tasmania, concerns have been raised that the salmon farm present has lead to deteriorating conditions including bacterial growth and reduction in dissolved oxygen’s levels in the harbour. However, the Environmental Protection Agency of Tasmania states with adequate regulation and risk management plans (stock size limits, monitoring, waste disposal and site selection) in place, salmon farming can be sustainable. An international example of this is in Uggdalsfjorden, Norway, where a balance between salmon farming inputs and the surroundings has been achieved.
The wrap up
There are many factors we should take into consideration when choosing any foods to consume, not just salmon alone. Firstly, both farmed and wild-caught salmon are healthy and safe to eat. Wild caught salmon does have less fat (the good and not so good kinds), less calories and slightly more minerals when compared to farmed salmon. However when compared to other meats, farmed salmon still scores as a healthy source of Omega-3 PUFA in our diet. The higher contaminant levels in farmed salmon are varied among species, location and even food preparation; results are not consistent enough to show evidence that it is unsafe to consume farmed salmon. Currently there is no right or wrong choice when considering which salmon to purchase and consume, it comes down to personal opinion on wild or caged animals, environmental politics, budget allowance and what is available in your area. What is more important is that we consume within the target range of 2-3 serves (200-300g) of fish per week, for health and sustainability, any portion of salmon within this range provides health benefits and poses minimal risk.