Health practitioners have good reason to encourage consumption of fish and seafood. The omega-3 fatty acid rich, low saturated fat protein has been shown to have numerous benefits for cardiovascular health and inflammatory conditions. As we consume more of this protein we need to start looking at the sustainability of these recommendations. Up to 35% of Australian seafood comes from aquacultures, (fish farms) including prawns, oysters, tuna and salmon. What do we need to know about fish farms to ensure we are making the most sustainable option?
Are fish farms the way of the future? Or do we still have a thing or two work on.
Marine aquaculture uses large netted cages floated under water in estuaries or bays to hold schools of fish. Fish raised in this environment are then usually fed a diet of fish meal, which is made from small wild fish such as mackerel and sardines, and usually mixed with grains. It can take up to 12kg of fishmeal to produce 1kg of farmed tuna and, and up to 4kg of fish meal to produce 1kg of farmed salmon!
How Fish Farms Affect Our Health
There are concerns that farmed fish contain more total fat but less omega-3 (the good fat) as well as a possible higher concentration of toxins called PCB (linked to development abnormalities). This is due to eating a diet of wild fish since a young age (ingesting a greater amount of chemicals) as compared to wild caught fish that feed off krill until they are older. On top of this, farmed fish are fed antibiotics and vaccines to combat diseases suffered from living in cramped conditions.
How Fish Farms Affect Our Environment
Damage to coastlands, affecting biodiversity and reducing mangroves, coastal wetlands and coral reefs is another concern. Of even greater distress is the water pollution caused by farm wastes such as uneaten fish food and excrement (which may contain antibiotics) passing out to the open ocean.
When farmed fish escape there is also the risk of spreading disease or interbreeding with wild fish, causing genetic pollution of the wild species and potentially reducing their ability to survive. In Norway studies have shown that a large number of wild salmon are dying from sea lice infestations they contracted when migrating past salmon farms.
A Word About Australian Salmon
Almost all the salmon purchased in Australia is farmed Atlantic salmon, which is not a native species and is often marketed as Tasmanian salmon. There are concerns about the amounts of antibiotics used in Australian salmon and the high amounts of PCB and dioxins. Often synthetic food colouring is used to give the salmon flesh a pink hue which is often seen in wild salmon due to their diet of krill. Wild Australian salmon does exist but is not readily available. The South Australian Fishery, which catches the native Australian salmon, has been recognised as using sustainable fishing practises with relatively small ecological impact.
Fish raised in inland ponds and dams have less environmental impact due to the enclosed system they are raised in. Fish such as carp, catfish, crayfish and eels do not require fishmeal at all. Other small herbivorous fish may only need 2kg of feed to produce 1kg of meat. Although, some freshwater carnivorous fish like trout and barramundi are fed fishmeal pellets, which has a harmful impact on wild fish populations used to make the feed.
When Farming Is Better
- Wild-caught scallops are often fished using seafloor dredges or trawls which are invasive and damaging and result in significant bycatch. Choose farmed over wild.
- Wild abalone is also fished using methods that have significant impact on local ecosystems. Choose farmed over wild.
- Oysters and mussels are filter feeders, gaining nutrients from microalgae and other plant matter in the water around them and therefore don’t require any extra feed. Both are good choices with little environmental impact.
- Squid, cuttlefish and octopus are caught using sustainable fishing methods and are generally fast growing, robust animals. However, canned baby octopus from the Gulf of Thailand is overfished and should be avoided.
- Crayfish (Yabbies) are farmed in small ponds and tanks and have minimal impact on the environment. Wild fisheries are a concern due to the degradation of our streams and rivers which has had a significant effect on wild yabby stocks.
There are environmentally sustainable seafood choices out there, but it is up to us the consumer to ask the necessary questions. The more we as consumers ask about different species of seafood, the more retailers will start to listen. As a general rule, avoid sea-farmed fish and choose freshwater herbivorous farmed varieties instead. Not only do they have less impact on the environment, but they will contain less chemicals and pollutants.
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Rachel Dickens, The Conscious Dietitian, is a Registered Dietitian and Certified Diabetes Educator. She graduated with her Masters in Nutrition and Dietetics in 2010 from Griffith University. She strives to provide evidence-based nutrition information with a focus on plant-based nutrition, and share some of her favourite seasonal recipes and sustainable eating tips.