70 Fish as feed inputs for aquaculture – Practices, sustainability and implications
reflected in the sector globally. One possible reason for this trend could be the limitations
on land and freshwater resources that prevent further expansion of inland aquaculture.
Asia, the continent blessed with the greatest amount of freshwater resources, has the
least per caput availability (Nguyen and De Silva, 2006). Another possible factor is
water quality degradation that has arisen from anthropogenic developments in most
watersheds in Asia, in particular, deforestation (Sodhi et al., 2004) and industrial
effluent discharge, making water resources unsuitable for aquaculture. Although
quantitative data are not readily available, frequent media portrayals of localized fish
kills in cages are common, providing indirect evidence.
The growth rate of crustacean culture in the rest of the world has declined over the
years, as opposed to that in Asia (Figure 6 b, d). It is also important to note that the
relative increase was much lower in all instances in Asia, reflecting the fact that Asian
aquaculture had reached considerably higher levels of production than the rest of the
world prior to the 1980s (FAO, 2006b; De Silva and Hasan, 2007).2.1 Trends in Chinese mariculture
The economic upsurge in China over the last 10–15 years has resulted in rising living
standards and an increase in the proportion of the middle class, with higher disposable
incomes. Consequently, this upsurge has impacted on the culinary habits of the
Chinese population, leading to an increase in the consumption of high-value seafood
species. This trend has been exacerbated by the perception that seafood offers better
eating quality and certain health benefits. Driven by these factors, China is increasingly
turning to the culture of high-value marine and freshwater fish. In the course of the
expansion and intensification of aquaculture of such high-value species (which areFIGURE 4
Total global and Asian cultured freshwater, brackishwater and marine crustacean
production, expressed as the mean per year for five-year periods from 1980 to 2004a. Marine crustaceans b. Brackishwater crustaceansc. Freshwater crustaceansSource: FAO (2006a)74%52% 48%77%74%02040608010005010015020025030080 - 84 85 - 89 90 - 94 95 - 99 00 - 04A sia's p ercent co ntrib utio n
Production (thousand tonnes)Asia Rest of the world %Years80% 86% 86% 82%91%02040608010002004006008001 0001 2001 4001 60080 - 84 85 - 89 90 - 94 95 - 99 00 - 04Production (thousand tonnes) A sia's p ercent co ntrib utio nYearsAsia Rest of the world %8% 22%52%88%97%020406080100010020030040050060070080080 - 84 85 - 89 90 - 94 95 - 99 00 - 04Production (thousand tonnes)YearsAsia Rest of the world %A sia's p ercent co ntrib utio n