Bred to last , The Australian, December 18, 2010
IT'S time to ditch the negative ideas about farmed fish, argues John Newton.
When The Troggs sang “Wild thing, I think I love you”, I doubt they were thinking of fish. But when I think of wild things, I do. We’re running out of them. Wild-caught fish, that is, so it looks like we’ll have to get used to eating more of the farmed variety.
According to a 2006 prediction by the United Nations Food and Agriculture Organisation, 2010 is the year the world began eating more farmed than wild-caught fish. The figures aren’t out yet, but that’s the way it’s been heading. Aquaculture is the world’s fastest-growing animal food-producing sector, with an average annual growth since 1970 of almost seven per cent.
This may not be such a bad thing. Certainly not according to Dr Brett Glencross of the CSIRO, a world authority on aquaculture nutrition. “I’d rather eat farmed fish than wild fish,” Glencross says. “I know the harvest has been managed and the quality is going to be excellent. You go to a barramundi farm … the animal is corralled into a cage and swims into an automatic stunner, falls into an ice slurry and immediately goes to zero degrees. The same technology is used on a salmon farm. By contrast, you buy a wild-harvest barramundi from a creek in the Northern Territory. The fisho sets a gill net overnight. By the next day, the fish has been dead overnight in 30-degree water.”There are basically two main methods of fish farming: mariculture, or farming in the open sea, in which the produce (usually salmon, kingfish, prawns and oysters) is held in cages; and closed tank, or land-based farming, where the fish (usually silver perch, Murray cod, trout and barramundi) are raised in tanks using recirculated water.
So, freshness aside, is farmed fish as good for you as wild-caught fish? How about the taste? And is the practice of farming fish environmentally sustainable? Here, we look at the key issues surrounding aquaculture.
What they’re fed: The figure bandied about by aquaculture critics is that it takes 5kg of wild fish to make 1kg of fishmeal. And that’s true, but today Australian fish farmers are using less and less fishmeal. Why? Duncan Leadbitter is a seafood sustainability specialist and director of the consultancy firm Fish Matter. “It’s declining because we’re learning a lot more about the dietary needs of these animals. In the past we would shovel in some fish and feed them the closest to what they would eat in the wild.”
Even when the industry moved to pellets in the 1980s, it didn’t get much better, as Glencross explains. “When barramundi were first fed pellets, they used to contain 50-60 per cent fishmeal. The latest generation of feeds now get down to as low as 15 per cent without impacting on the performance or health of the fish.”
So what is the fishmeal replaced with? “Part of my role is identifying all the micro and macro nutrients in the fish and shrimp diet,” says Glencross. “We look at what they eat naturally and what they eat when they have a compounded diet [a mixture of plant and fishmeal] and then make a comparison.”
It’s common practice in Australia to blend fish oils used in the diet with poultry or canola oils. “The fish do well with that but it does tend to dilute the long-chain Omega 3 oils [the ones that are good for us],” says Glencross. “That said, of all the fish you get at the supermarket, farmed salmon is still the highest in Omega 3.”
It’s not only environmental concerns that are driving research into using more plant material. Fishmeal is expensive. Blending it with poultry, lupin and canola meals makes financial as well as environmental sense. And, according to Glencross, “we can raise them on high levels of grain and they do just as well as on high levels of fish oil”.
According to a 2010 report on aquaculture nutrition, salmon farmers in Australia use, on average, the lowest amount of fishmeal in the world. Roy Palmer, president of the Asia-Pacific chapter of the World Aquaculture Society, says our level of sustainability is ranked in the highest category. “Clearly, other countries have got to work their way up to our level,” he says.
Pollution: One of the main agricultural pollutants is nutrient run-off from the use of fertiliser and manure, and it’s definitely a problem when fish are farmed in sea cages. There are two causes: overfeeding, and concentrations of fish excrement in the sea underneath the cages.
There are several ways to avoid overfeeding on the modern fish farm. Firstly, fish pellets float, so the farmer can see if there’s too much going in. Secondly, some farms, such as New Zealand’s King Salmon, have cameras in the cages to ensure that when the fish have eaten enough, no more is dispensed.
The problem of what goes around and under the fish cages is solved by fallowing – moving the cage and leaving the area to recover. This is mandated in South Australia and Tasmania, but not in NSW, where it is simply considered “best practice”.
Antibiotics: Glencross cites a 2009 report showing that 10 to 12 tonnes of antibiotics were being used in aquaculture every year. The salmon industry and one of the major feed companies contacted the CSIRO to help resolve this. “Through better nutritional management, antibiotic consumption went from 10 tonnes a year to 100kg,” he says. Now, salmon farmers in Australia only administer antibiotics under veterinary prescription.
Cage chemicals: The practice of using copper-based anti-fouling paint on cages, widely criticised by environmentalists, is being phased out. Dr Geoff Allan, the aquaculture director at NSW’s Port Stephens Fisheries Centre, says that within three years “more than half [Australia’s] fish farms will replace the nets using the anti-fouling paint with plastic ones, or begin using automatic net cleaners, an Australian industry innovation.” Allan says about 25 per cent of farms have already stopped using anti-fouling paint.
Quality: Isn’t one farmed salmon much like another? Seafood industry consultant John Susman puts it like this: “It’s very rare that you see a fish farmer approaching their work the way a vigneron growing pinot noir does, having a direct relationship with the product that ends up in the bottle.”
Rare, but not unknown. Neville Rockliff began fish farming at Petuna Seafoods, a company started by his parents in Tasmania, in 1991. Very soon after the farm began, chef Tetsuya Wakuda from Sydney restaurant Tetsuya’s began working with Rockliff on selective breeding of their ocean trout.
“Harvesting fish is like harvesting cattle and sheep – there’ll be good ones and bad ones,” says Rockliff. “Tets would come down and we’d pick the larger fish with good skin colour – nice silver fish with bluey green backs – and we’d breed from them every year. Our average fish when we started was 2.5kg; now they’re 4-4.5kg.” To this day, Wakuda uses Petuna for his signature confit of ocean trout with konbu and fennel.
King Salmon in New Zealand farms Chinook salmon for its Regal brand. This variety contains double the Omega 3 of the Atlantic salmon farmed in Australia and has found favour with chefs such as Greg Doyle of Sydney’s Pier, who serves it raw in a dish of citrus-cured salmon pastrami, and Josh Emett of Maze Melbourne, who also citrus-cures it and serves it with bok choy and white asparagus.
Pink or grey? Don’t they use dye to make salmon pink? Yes, astaxanthin, a nature-identical additive that gives the salmon the colour a wild fish would have from eating crustaceans. It’s also hailed by some natural health proponents for its antioxidant and anti-inflammatory qualities. Without it, salmon would be grey.
Imported products: Currently, 70 per cent of the fish eaten in Australia is imported, most of it farmed – fish such as basa and tilapia and prawns such as vannamei. How sustainable are they? “I do think they need to clean up their act a bit,” says Glencross. “There are a few issues where they wouldn’t meet the criteria we adopt in Australia.”
Roy Palmer has a different view. “At a recent international seafood and health conference I made sure that the celebrity chefs cooking for us had basa and tilapia on the menu,” he says. “They’re priced to feed people seafood – an essential part of the diet – in an economical way.”
So which farmed seafood will you be choosing for your Christmas table? Glencross has crunched the numbers, based on a series of sustainability criteria published by the World Wildlife Fund. He then ranked all the Australian aquaculture industries according to how well they score on those criteria. This is how it panned out: 1. Australian farmed prawns; 2. barramundi; 3. salmon; 4. oysters; 5. freshwater trout.
Those wild things may still make your heart sing, but if we want to continue to eat fish for health and pleasure, we’re going to have to change our tune.
