Aquaculture - or fish farming - involves the production of fish, molluscs and crustaceans in nets, cages or hatcheries to enhance production quality and volume¹. Deloitte Access Economics recently valued the direct economic contribution of the Australian marine based aquaculture industry at $994.4 million2. Over 40 species of fish and seafood are farmed in Australia including Atlantic salmon, barramundi, mussels, prawns and oysters3. Marine based fish farming is the primary form of aquaculture activity in Australia. Freshwater aquaculture does exist, but contributes very little - less than 4 percent of total aquaculture production4.

The share of fish and seafood produced by aquaculture has climbed steadily over the last two decades. From virtually nothing in the early nineties, to 36 percent currently (Figure 1). Worldwide, this figure sits at about half of total seafood destined for human consumption5.

Figure 1: Total volume of production, Australia

Fish farming has existed for centuries. There is evidence suggesting Aboriginal populations ‘farmed’ eels, crayfish and yabbies as early as 6000 BC6. Its modern comeback over the last two decades has been driven by growing demand from consumers for high quality, fresh seafood (Figure 3), particularly in developed nations. Worldwide, annual seafood consumption averages 24 kilograms per capita7. Australian consumers are expected to consume 29 kilograms of seafood each over coming financial year8, a figure that is expected to continue growing in the future. Seafood is seen as a healthier and more sustainable alternative to other sources of protein such as chicken. But with more than 90 percent of wild caught global fish stocks depleted or overfished, wild catch cannot meet the growing consumer demand - enter aquaculture9.

Figure 3: Per capita consumption of seafood

While aquaculture is often heralded as the sustainable solution to depleted ocean stocks, there are concerns regarding its sustainability, the health of farmed fish and ecosystem impacts. Principally these relate to: 

• Consumption of fish based feed: Many farmed fish, including salmon and trout are carnivorous. These fish eat a feed manufactured from smaller fish taken from the oceans. This means that although the farmed fish are not taken from depleted ocean stocks, the fish they feed on are. This limits the sustainable expansion of aquaculture until other sources of feed are found.
• Catching wild juveniles to be matured in farms: Eels and Southern Bluefin tuna are both considered depleted ocean stocks. Currently these species are caught as juveniles and then farmed intensively to saleable size10. This practice does not allow ocean stocks to replenish to sustainable levels.
• Transmission of viruses from farmed fish to wild stock: The higher density of farmed fish can increase the transmission of viruses if fish effluent is poorly managed. Not only can this produce poor quality farmed fish, but there are additional concerns that viruses in farmed fish can spread to the wild stock. If viruses spread to the wild this could have severe impacts on already overfished species.
• Ecosystem impacts from the operation of fish farms: The construction of a fish farm may result in the destruction of shoreline habitat for birds and other shoreline marine life. This is a particular concern for aquaculture operations in China, Thailand and other parts of Asia11
• .Ecosystem imbalances: Introducing a large volume of foreign fish to a body of water may have impacts on the existing ecosystem, particularly where the nets or cages extend to the seabed. 

Despite these sustainability concerns, Australian aquaculture is often regarded as having best practice stock control, fish health and wastewater management. A recent innovation by the Australian CSIRO is a marine microbial prawn feed (NovacqTM) and creates hope for further innovations in fish based feed. Not only does this feed reduce reliance on fish based feed but it produces healthier, faster growing prawns than those fed by fishmeal or fish oil. If Australian aquaculture can position itself as a sustainable, healthy option for the increasingly health and eco minded global consumer, then it could expand its export market, which currently accounts for 1.4 per cent of the total volume of Australian production12.