Aquaculture: Saviour or Villian?

by Jim Curtis (2000)

Aquaculture is currently being promoted as potentially one of the most commercially lucrative industries of the new century. It is also seen as a partial solution to problems associated with growing population numbers, declining food supplies and unsustainable wild fish stocks. But there are concerns that modern aquaculture activities may be a source of more problems than solutions, and will contribute to the already declining integrity of the world's oceans and river systems.

One of the simplest definitions of aquaculture is the farming of aquatic organisms. But such simplicity is not characteristic of today's aquaculture industry. A complex range of techniques are used for breeding, cultivating, harvesting and marketing varieties of aquatic plants and animals that include fish, molluscs, crustaceans and algae. Aquaculture operations may be freshwater, marine, land-based or open water activities, and typically involve controlled environments that 'assist' natural processes by employing artificial methods of stocking, rearing, feeding and protection. The concept and management strategies of aquaculture are therefore very similar to its terrestrial counterpart, as they both share the objective of maximising production and minimising costs for commercial gain.

Some recent global trends and issues have made justifying and arguing the need for aquaculture activities relatively easy. For example, many commercial wild fish stocks are currently in decline because they have been exploited at unsustainable levels for many years, and have been decimated by the impacts of pollution and habitat destruction. Combined with an ever-increasing world population and a growing appreciation for seafood, these pressures are creating demands and expectations that cannot be fulfilled by existing wild fish stocks. Aquaculture is therefore not only being promoted as a means of enhancing food production, but also a vital method of replenishing over-exploited species so they can recover to a sustainable level.

Although there are many persuasive arguments justifying the need for aquaculture, there are also numerous concerns regarding the industry's potential negative environmental impacts. These may include habitat modification or destruction caused by aquaculture developments, the pollution of the surrounding environment from wastes such as excreta, chemicals, uneaten food and dead animals, increased nutrient levels that can lead to excessive algal growth and the eutrophication of water resources, the introduction of disease and exotic organisms that may compete with native flora and fauna, and using unsustainable wild fish stocks as feed for aquaculture species. Another concern is the impact on natural predators, such as birds, seals, dolphins and sharks, that may get entangled in nets or are purposely killed to protect the 'products' being farmed. Conflicts may also emerge between the different uses of marine and coastal environments. While tourism, recreation, research, education and conservation activities generally prefer that the natural appeal and integrity of these environments are preserved, intrusive aquaculture operations will inevitably have a negative impact on wilderness values and the visual amenity. Given such competing interests, it cannot be simply assumed that such operations can be successfully integrated within a single environment or a responsible management plan.

There are numerous examples throughout the world where these 'potential' negative environmental impacts have unfortunately materialised. Some of the most well documented cases in recent years have been the detrimental effects of shrimp farms in Asia. These operations have been responsible for clearing huge areas of mangrove forests for the purpose of constructing a variety of aquaculture facilities. However, mangroves are an important natural resource as they provide a fertile breeding ground for many marine species, and help protect the terrestrial environment from the impacts of erosion and severe weather conditions. Mangroves also provide a natural filtration system for collecting sediments, pollutants and recycling essential nutrients. By removing them, it has not only disrupted the sustainable lifestyles of numerous small fishing communities that have traditionally relied on these mangrove ecosystems for food and other materials, but it has also threatened the future existence of the shrimp farms as many have since been ravaged by disease and floods. Further problems have arisen from the intense nature of these aquaculture operations, as the amount of chemicals used and the resultant waste has lead to the pollution, contamination and salinisation of the surrounding land and freshwater supplies, as well as poisoning native wildlife. Although such impacts must have been foreseeable during the design, construction and early operation of these aquaculture facilities, they were probably ignored given the allure of potentially massive commercial gains.

Australia has also suffered some recent aquaculture dilemmas. Over a two-year period, 32 dolphins and 5 seals died by getting entangled in the tuna farm nets that are part of South Australia's aquaculture industry. Along with Tasmania, South Australia is also currently experiencing problems with feral Pacific Oyster populations. This exotic species is considered a noxious pest in many parts of Australia where it threatens to prey, compete and breed with native species, and has the potential to introduce disease and adversely affect natural habitats. Although some Australian states banned the farming of Pacific Oysters in recognition of these dangers, South Australia did not because of 'scientific evidence' that claimed that natural inhibiting factors would prevent feral populations from ever breeding in the wild. But for scientists to make such assured predictions of nature's behaviour is very brave, and in this case they were also very wrong. The Australian government is now funding a research program to fully ascertain the environmental impacts of feral Pacific Oysters.

Despite such disasters, aquaculture continues to be one of the world's fastest growing rural sectors, with many governments remaining fearlessly committed to the industry's ongoing promotion and development. For example, the former government of South Australia's neighbouring state, Victoria, recently embraced a target to double the value of its aquaculture production by the year 2001. But concerns were instantly raised that the government may compromise environmental standards to achieve this target. It was soon discovered that these concerns were justified. As part of its commitment, the former government of Victoria conducted a regulatory review to identify impediments to local aquaculture growth and investment. The review suggested that current environmental standards were inhibiting the industry and that a simplified regulatory process should be embraced. One of the recommendations was therefore to replace legally binding EPA (Environment Protection Authority) licensing requirements with voluntary codes of practice for certain sectors. But such recommendations are environmentally dangerous, and illustrate the political context within which aquaculture operates. In the ongoing battle between economics and the environment, politicians continue to predominantly base their decisions on potential economic revenues rather than real environmental concerns. Although there has recently been a change of government in Victoria, these aquaculture-related concerns remain.

Population pressures, food shortages and declining marine and freshwater resources are serious problems that demand serious solutions. But aquaculture has yet to prove itself as such a solution because it currently has more of a reputation as an industry that is committed to maximising short-term commercial gains rather than achieving long-term economic and environmental sustainability. Unless this changes, aquaculture will become another chapter in a long history of human endeavours that have irresponsibly exploited and degraded the natural environment. Given that oceans and river systems are often described as the world's last great wildernesses, this is one chapter that should not be written.