高清福利片

World production of farmed fish overtook the production of farmed beef more than ten years ago. Then in 2018, farmed seafood for human consumption exceeded wild-caught seafood for the first time.

These aren鈥檛 just interesting and perhaps surprising pieces of trivia. They鈥檙e markers of a profound change in how we humans are producing our protein-rich foods.

The motivators towards aquaculture are not unfamiliar. Farming land animals is resource intensive, hard on land and waterways and too often, hard on the animals themselves. At the same time, there are about 4.6 million fishing vessels plying the seas, including massive factory ships, which have turned parts of the ocean into fish ghost towns and threaten some species with extinction.

While aquaculture is by no means a penalty free alternative, as the world population grows from around 7.8 billion today to a projected 9 billion by 2030, it presents opportunities to produce more protein using less, not just through farming fish, but also molluscs and crustaceans. This plays very much to the goals of聽Associate Professor Joy Becker聽(CertEd '10).

鈥淲hat gets me out of bed in the morning is food security,鈥� she says from her office at the University鈥檚聽Centre for Carbon, Water and Food聽in Camden, west of Sydney. 鈥淭he fact is, we need to be able to farm fish so it鈥檚 sustainable, safe for people to eat and affordable. Affordable is a big one.鈥�

Growing up in a fully land-locked part of rural Canada, Becker was always around beef and poultry but somehow became fascinated by fish. So what brought her to Australia? 鈥淚 was following the salmon,鈥� she says. 鈥淚 did my PhD in parasites and salmon have parasite problems. Suddenly, I was in Tasmania where the salmon farming industry was going gangbusters.鈥�

Tasmania isn鈥檛 the only aquaculture state. 鈥淚t鈥檚 everywhere in Australia,鈥� says Becker with some excitement. 鈥淣ew South Wales has oysters, Murray cod, silver perch. In Victoria it鈥檚 abalone and rainbow trout. WA and the Northern Territory do barramundi. Lots of prawns in Queensland. South Australia has southern Bluefin tuna and oysters as well. There鈥檚 also barramundi and yellowtail kingfish hatcheries. There鈥檚 lots more happening and nowhere is untouched.鈥�

Her aquaculture focus is fish diseases, giving Becker plenty to think about because it鈥檚 a serious issue for the industry. Fish farming is intensive, tending to put lots of fish in relatively small spaces, either ponds, tanks or enclosed by nets in the ocean. There are knock-on effects.

With sea cage farms, the copious fish waste falls into a very localised part of the ocean wreaking havoc on water quality and the ecosystem. Tank and pond fish farms can use lots of energy maintaining liveable environments for their fish. Plus they need plenty of water that then becomes tainted with fish waste.

Intensive fish farming also makes disease outbreaks virtually inevitable and the effects can happen on a grand scale. In one six month period, a salmon farm in Tasmania lost more than a million fish to Pilchard orthomyxovirus, most likely caught from native pilchards. Of course, it works the other way too; a fish farm disease can easily spread to wild populations.

Addressing these problems comes under the remit of the University鈥檚 Aquatic Animal Health team which has been operating now for 20 years. Through strong affiliations with a number of industry organisations, the team is responsive to issues as they arise and works to ensure new information quickly goes where it鈥檚 needed.

A large part of what Becker does in the team, is looking at how to prevent disease outbreaks and how to treat them in ways that don鈥檛 compromise the food value of the fish or fall foul of the rightly strict Food Safety Act. In fact, exported Australian seafood is highly regarded specifically because it鈥檚 clean and safe, meaning minimal chemical or drug residues.

鈥淚n Australia drugs are only used if the fish are sick, not as a preventative,鈥� says Becker. 鈥淚t鈥檚 all licensed drugs and you have to have a veterinarian prescribe them.鈥�

Another vital element for healthy farmed fish is feeding them the right food, complicated by the fact that some of the most desirable and profitable farmed fish 鈥� salmon, trout, tuna, barramundi 鈥� are carnivores. They eat other fish. So any thought that farming fish takes pressure off wild fish populations, doesn鈥檛 fully play out.

However, farmed fish aren鈥檛 fed whole fish. They鈥檙e fed pellets containing fish meal made from anchovies and pilchards caught off the coast of South America. The fishmeal market is growing as vigorously as the aquaculture industry.

鈥淭he cost of the pellets is greatly impacted by the El Nino/La Nina weather cycles which affect wild fish numbers,鈥� says Becker. 鈥淲e have years聽with lots of fishmeal and fish oil, with relatively low prices. We have lean years when prices can double, impacting the farmers.鈥�

Minimising the amount of fish meal in food pellets, while maintaining fish health, has been the subject of intense research for a number of years. Various vegetable-based options have been considered, but they lack something essential in feed for carnivorous fish; enough omega 3 fatty acids. The search continues.

Still, the core benefit of fish farming remains; it鈥檚 efficiency in converting feed into useable protein. Where land animals carry themselves heavily across the earth, fish are in a buoyant environment, and therefore able to grow on substantially less food. Carp, shunned in Australia but a popular food source internationally, requires fifteen times less food to produce, kilo for kilo, than beef.

Another key benefit of aquaculture is it can be established in more places.聽Some Australian graziers are converting land to aquaculture, particularly for freshwater crustaceans like crayfish, while Indonesia, and many other South East Asian countries, are finding huge economic and employment benefits in sating China鈥檚 ravenous hunger for seafood.

鈥淭he Indonesians produce high value fish species for export 鈥� grouper and barramundi,鈥� says Becker who is often in Indonesia working with local fish producers. 鈥淭he income from those fish means people can buy food they want to eat in their local economy.鈥�

Soon we might have to rethink the idea of plenty more fish in the sea.

FOOD SECURITY AND ANIMAL WELFARE
To find out more about this story or to help sustainably advance aquaculture please call Judith O'Hagan on +61 2 8627 8818 or email development.fund@sydney.edu.au.

Written by George Dodd for the Sydney Alumni Magazine. Photography by Stefanie Zingsheim.聽