of PGRFA, their sustainable use and the sharing of benefits arising from their use. It also contains mechanisms for facilitated access and benefit sharing through its Multilateral System. Many signatory countries (116 in June 2007) are yet to implement the Treaty. Policy options range from contributing to the Global Crop Diversity Trust (currently mainly OECD countries, but also countries like Colombia and Brazil), to establishing or expanding national ex situ collections (e.g., India), and for liberal or restrictive regimes for access to these collections, including the sharing of information on these resources. The agricultural sector generally supports liberal access regimes in order to promote availability of genetic resources for plant breeding in support of food security and rural development.

On-farm policy approaches to management of genetic resources include various types of support to farmers who maintain and further develop genetic resources, such as payments based on cultural heritage (e.g., historic cattle breeds), technical support to foundations for crop-hobbyists (e.g., old apple variety clubs in Europe) to participatory plant breeding strategies in many developing countries (Almekinders and Hardon, 2006). Such mechanisms may conflict with existing policies and laws that focus on seed system development, including seed laws, plant breeder's rights, etc. The EU recently developed the concept of "conservation varieties" for this reason. National policies to bring these objectives in harmony with each other are supported by the concept of Farmers' Rights of the IT PGRFA. However, countries may make these rights "subject to national law and as appropriate" (Art. 9 - IT PGRFA) which provides broad options for national priorities and implementation strategies. The use of a range of standard economic tools (taxes, subsidies, "cap and trade" with permits) can help maintain higher level of plant genetic diversity in seed markets recognizing that information barriers limit market efficiency (Heal et al., 2004).

Recent advances in molecular biology have provided a whole new set of tools for investigating biodiversity, including the diversity of agricultural plants and animals. While there has undoubtedly been significant loss of diversity over time of plant and animal genetic resources for agriculture at the varietal level, there is some evidence that overall losses of genetic diversity when measured at the genetic level have not been so great and that modern biotechnological breeding tools can regenerate some of this diversity, especially if the tools can be transferred to developing country agricultural research levels through support for initiatives such as African Agricultural Technology Foundation and Public Sector Intellectual Property Resource for Agriculture (PSAPRA) (USDA, 2003).

Livestock.The livestock sector is an important source of greenhouse gases and factor in the loss of biodiversity, while in developed and emerging countries it is a significant source of water pollution.1 Current decision-making on the livestock-environment-people nexus is characterized by se-

1 (The following text draws heavily on a major review of the negative impact of livestock production on the environment by Steinfeld et al., 2006.)

vere underpricing of virtually all natural processes that go into livestock production process. This includes neglect of major downstream externalities. Limiting livestock's impact on the environment to more socially optimal levels requires measures to reduce land and other natural resources requirements for livestock production. This could be achieved by intensification of the most productive arable and grassland used to produce feed or pasture; and retirement of marginally used land, where this is socially acceptable and where other uses of such land, such as for environmental purposes, are in demand, and have higher value. Intensification can lead to gradual reductions of resource use and waste emissions across the sector. For example, precision feeding and use of improved genetics can greatly reduce emissions of gases (carbon dioxide, methane, etc.) and of nutrients per unit of output.

The major policy goals for addressing environmental pressure points arising from current policy and market processes in the livestock sector are:

• Controlling expansion into natural ecosystems;
• Managing rangeland in a sustainable way;
• Reducing nutrient loading in livestock concentration areas; and
• Reducing the environmental impact of intensive feed production.

Because the major stressors arising from the livestock sector differ in different parts of the world-ranging from overgrazing in Australia and sub-Saharan Africa, biodiversity loss from pasture expansion in Latin America, to pollution arising from intensive pig production in Europe and SE Asia-the mix and emphasis of the policy instruments will need to be different in different parts of the world, but could include measures to:

• Limit livestock's land requirements,
• Correct distorted prices,
• Strengthen land titles,
• Price water and water quality internalizing all externalities,
• Remove subsidies,
• Liberalize trade, and
• Support intensification and promoting research and extension of cutting edge technology.

The choice of policy instruments should take into consideration the broader goals of efficiency; effectiveness and equity (Hahn et al., 2003), given the major economic contribution and social role played by the livestock sector globally.

Aquaculture."Traditional" aquaculture has been an integral part of one of the world`s most sustainable agricultural systems-the polyculture Chinese fish-farm (FAO/IPT, 1991) for around 3000 years, but recent rapid expansion of commercial aquaculture, in the absence of appropriate policies, is generating negative environmental and social impacts that threaten to undermine the long-term sustainability of the industry. In recognition of these growing negative impacts, broad environmental management principles have been agreed for the sector (e.g., FAO Code of Conduct for Responsible Fisheries, Article 9; FAO Technical Guidelines