Diversity, Complexity, and Dynamics in Aquaculture

Aquaculture, the farming of aquatic plants and animals (finfish, crustaceans, molluscs and other invertebrates), in fresh-, brackish, and seawater, is very diverse (Stickney 2000). Aquaculture statistics reported to the FAO from its member countries in 2000 covered 210 different species (Tacon 2003). Aquaculture systems are commonly classified according to their nutrient inputs. Extensive aquaculture involves no intentional fertilisation or feeding; e.g., the capturing of naturally settled mussels and oysters. Semiintensive aquaculture comprises the farming of fish and invertebrates in ponds, pens and cages with supplementary fertilisation and/or feeding. Intensive aquaculture is entirely reliant on added feeds (e.g., salmon cages, eel tanks and raceways) and resembles feedlot systems for livestock. Fish farmers are also diverse. They range from poor smallholders in developing countries to the world's largest corporations. Their operations range in scale from backyard ponds of less than 100 m2, operated by rural and periurban households, to enterprises that cover thousands of hectares of land and water with ponds, pens and cages. Aquaculture is as diverse as agriculture.

Aquaculture, like agriculture, is also a highly complex sector, comprised of sub-sectors (breeding, hatchery and nursery operations, grow-out and marketing, etc.) and interdependent with a wide range of associated industries; e.g., feeds, fertilisers, medication, and equipment. The diversity and complexity of aquaculture inevitably make it a very dynamic sector. Its dynamics include its rapid growth, as a new frontier for food production in many countries, and its necessary coexistence with other longer established sectors. The intersectoral relationships of aquaculture with agriculture, capture fisheries and other sectors are often areas of conflict and it is a major future challenge for aquaculture and those other sectors to resolve their conflicts and to pursue co-operation, especially in the sharing of land, water, and other natural resources (Sumaila 1999). Aquaculture has great scope for integration with other food production sectors. Fishponds in mixed farming systems and aquaculture integrated with wastewater reuse also have long histories and huge potential (e.g., Edwards 2000; FAO 2000a; Edwards et al. 2002). A governance approach to aquaculture is just beginning (Van der Schans 1999).