Farms within each survey region ten

Farms within each survey region tended to share similar production methods, but each region differed in system design (Table 1).

Although our sample was oriented around carp and tilapia producers, a striking outcome of the survey was the large number of other species also raised in these systems—31 different species farmed in total (see Appendix Table 2).

Farmers in Shandong mostly raised a mixture of carps in traditional pond polyculture systems.

In addition to the traditional integrated systemcontaining grass-, silver-, bighead-, and black carp, many farmers also raised crucian carp that typically depend on commercial feeds containing fishmeal.

Polyculture was also prevalent in the other carp-based regions; however, these systems were not necessarily
designed to optimize feed efficiency or minimize wastes).

5 Jiashan had the highest average number of species grown, with a variety of carps farmed alongside other higher-value species, such as soft-shelled turtles (Pelodiscus sinensis), whiteleg shrimp (Litopenaeus vannamei), Chinese mitten crab (Eriocheir sinensis), and rainbow trout (Oncorhynchus mykiss).

Qiandaohu farmers also grew a rich assemblage of species that included carps aswell as higher value finfish, such as yellowcatfish (Tachysurus fulvidraco), longsnout catfish (Leiocassis longirostris), and Wuchang bream (Megalobrama amblycephala).

Qiandaohu was also unique among the regions surveyed in its use of floating cages in lakes.6 Farmers surveyed in Hainan produced predominantly tilapia.

These farms cannot be considered strictly monocultures, however, as it was common to keep a few carps and other fish for bio-control purposes (e.g., to improve water quality and fish health).