Fish provide more than 2.6 billion people with 20 per cent of their intake of animal protein (FAO 2004). With wild fish stocks fully exploited - and the human population rising - mariculture can provide an important dietary staple to a hungry planet. If guided by sustainable principles, and supported by effective policies, mariculture's adverse effects on biodiversity can be blunted. Sustainable principles can:

● minimize multiple stresses, including better control of land pollutants discharged into the coastal zone, to make mariculture more   economically and ecologically viable;
● promote integrated fish farming systems that reduce waste and use the most regionally appropriate species;
● provide access to best practice information, such as strategies for pollution prevention or disease control, to decision makers and    practitioners; and
● encourage adaptive management to allow for local, regional or global changes in the environment and the economy.

Sustainable policies to mitigate environmental damage caused by mariculture include (World Fisheries Trust 2002):

● feed changes. Reformulate feed to include less animal protein so as to reduce phosphorus and nitrogen waste;
● waste reduction. Eliminate or contain effluent from farmed species and make more efficient use of feeds;
● seedstock protection. Reduce use of wild fry or larvae as seed for cultured species; ● chemical use. Reduce use of chemicals and    antibiotics;
● disease transmission. Promote management practices that reduce stress on farmed species and guard against escapes; and
● exotic species. Broaden use of native species and promote recovery of exotic species escapes.

To protect biodiversity in the world's oceans - and the food supplies they support - sustainable wild fisheries management practices should accompany mariculture development, including the establishment of a no-fishing marine reserve system. Mariculture regulation should be comprehensive, addressing proper siting of operations to minimize environmental impacts as well as long-term rights and responsibilities should any environmental damage occur.

Permissions to establish operations should be also legally rigorous to ensure that parties granted rights are held accountable for environmental or ecological problems and that the operation cannot be implicated in any illegal, unregulated or unreported fishing activity. The offshore oil and gas industry - which has a long history of successes and failures regarding siting, operations and remediation - could provide valuable lessons for the burgeoning ocean fish farming industry.