World Food Policy Volume 3, No. 2/Volume 4, No. 1, Fall16/Spring17 | Page 46

World Food Policy Figure 5. The Area and Production of Freshwater Aquaculture in Hai Duong Province (1997–2014) Source: Hai Duong Statistical Book, 1999, 2005, 2014. from 1997 to 2005, while only 38% of total households established their fish cultures during the period 1980–1996 (Table 4). the last decades. It changed not only in the structure of the food it produces, but also in its production systems, espe- cially for the freshwater production sys- tems. The total production of fish in Hai Duong rose from 9,963 tons to 64,887 tons from 1997 to 2014. There was also a significant increase of aquaculture in the area, from 5,660 (ha) to 10,064 (ha) during the period 1997–2005. The turning point of aquaculture expan- sion was in 2005 when the Vietnamese government set up a program of food security which prioritized a large area of agricultural lands to maintain rice production (3 million ha) in order to ensure the national food security pro- gram. This has clearly impacted the aquaculture expansion in the province. As it was, 70 households (46%) out of the total (151) investigated households started their fish cultures in the period The essential characteristic of IAA systems is the flow of nutrients be- tween enterprises, i.e. wastes from one enterprise become inputs to another in order to increase production. These wastes do not flow exclusively to the pond, but from the pond to other en- terprises (in the form of pond mud and nutrient-rich water) such as in vegeta- ble production around the pond. Some of these new enterprises and flows may only have been feasible through the introduction of the pond. Increased enterprise diversity provides opportu- nities for more nutrient linkages, and a possibility to meet increased nutrient requirements for enhanced production, 46