environmental impacts such as excessive use of agrochemicals (fertilizers and pesticides) resulting in water pollution, which affects human and animal health and indirectly damages ecosystems. An example is the intensive and continuous monoculture of rice-wheat systems in the Indo-Gangetic Plain of India and Pakistan, which led to soil and water degradation that has canceled the gains from the green revolution (Ali and Byerlee, 2002). In all regions, especially in the heterogeneous and risky rainfed systems of sub-Saharan Africa, there is a need for sustainable technologies that increase the productivity, stability and resilience of production systems (Conway, 1999). It is important to note that most rice-producing areas such as China, India, Japan and Indonesia have experienced stagnation in rates of productivity increase as of 1985-2000 (Cassman, 2003).

The fishery component of agriculture

Fisheries play a very important role in agriculture and the world economy. Rapid population growth in developing countries, changing consumer preferences and increased disposable income have increased global demand for fishery products. About 200 million people worldwide, most of them in developing countries, live on fishing and aquaculture, and fish provides an important source of food, cash income for many poor households, and is a widely traded food commodity (Kurien, 2006; WorldFish Center, 2006). Over a billion people worldwide rely on fish as their main source of protein or their most inexpensive source of animal protein. In 2004, aquaculture production accounted for 43% of fish consumption (FAO, 2006b). Fish contributes to national food sufficiency through direct consumption and through trade and exports.

     Total fishery production in 2004 was 150.5 million tonnes, of which 45.5 million tonnes were from aquaculture, of which 40% that entered international trade reached a value of US$71.5 billion (FAO, 2006c). While capture increased moderately from 1970 to 1998, aquaculture multiplied by a factor of 15 in the same period, from about 2 million tonnes in 1970 to about 30 tonnes in 1998 (Delgado et al., 2003; Figure 1-10). Fishery exports have become a significant foreign currency earner for many developing countries, contributing slightly less than 50% of such exports. The export value of world trade in fish, US$58 billion in 2002, is more than the combined value of net exports of rice, coffee, sugar and tea (World Bank, 2004a). Demand for fish products is increasing rapidly as income levels rise in Asia and the population grows in Africa. Led by Asia, developing nations produce nearly three times as much fish as industrialized countries (Delgado et al., 2003).

     World capture fishery production was from 90 to 100 million tonnes in 2005, an increase of about 5% from 2003 (FAO, 2006c). Aquaculture may substitute for wild catch but can create environmental problems, especially when practiced intensively, such as in large-scale, intensive operations, most of which (with the exception of shrimp farming) are found in temperate countries.

The forestry component of agriculture

Forests are intensively linked to agriculture, providing products (i.e., wood, fuelwood, food, medicines), inputs for crop and livestock production (fodder, soil nutrients, pollination, etc.), and services (i.e., watershed protection, climate regulation, carbon storage, biodiversity conservation). World roundwood production in 2004 reached an estimated 3,418