Use of wild fish and other aquatic organisms as feed in aquaculture in the Asia-Pacific 99species cultured, artificially formulated feeds for flatfish and breams are relatively well
developed. The use of pellet feeds is rather common in indoor marine finfish culture,
formulated feeds accounting for more than 90 percent of the feed consumed. Less than
10 percent of the feed used consists of trash fish or farm-made feeds that include trash
fish as a major ingredient. Overall, the indoor culture of marine finfish consumes
90 000 to 100 000 tonnes of trash fish annually.
Pond culture of marine finfish occurs primarily in Fujian, Zhejiang and Jiangsu
provinces, with an estimated annual yield of about 250 000 tonnes. In coastal pond
culture, which is often in the inter-tidal zone, about 20 percent of the pond area is
under extensive culture with very limited feeding. About 50 percent of the ponds
culturing bream and other perciform fish use formulated feeds. Most other pond-
cultured species depend on trash fish/low-value fish as feed or on farm-made feeds
containing trash fish/low-value fish as a major ingredient. Trash fish consumption in
marine finfish pond culture is estimated at 750 000 to 800 000 tonnes per year.
The current annual output from cage culture is about 300 000 tonnes. A local survey
showed that the use of pellet feeds for cage culture in Zhejiang and Shandong provinces
is proportionally higher than in Fujian and Guandong provinces, where most cage
operators still use trash fish/low-value fish directly as feed (Xianjie, 2008). Nationally,
about 10 percent of marine finfish cage-culture production is estimated to use pellet
feeds. Another 30 percent of the production involves the use of trash fish/low-value
fish mixed with other feeds or farm-made feeds using trash/low-value fish as the main
ingredient. The remaining 60 percent of the production depends solely on the direct
use of trash fish/low-value fish as feed. Trash fish consumption by the marine
cage-culture industry in the country is estimated at 2 million tonnes per year.
The use of trash fish as feed has a direct bearing on the sustainability of aquaculture
development in China. Relying only on fish as feed can cause nutritional imbalance,
a lack of minerals easily leading to malnutrition, impaired immunity and reduced
growth rates in cultured stocks. Also, the supply of trash fish is inconsistent (seasonal
variations in availability impact on price; in China during the closed season, the price
of trash fish can rise to more than Chinese yuan (CNY) 3.0 per kg), its quality is often
variable, and transport and storage are much more difficult than for artificial feeds. By
contrast, the development and use of artificial feeds for the culture of cobia and yellow
croaker have demonstrated the following advantages:- reduced culture period;
- less pollution of the culture environment and hence lower risk of disease
outbreaks; - higher yield and economic efficiency, and
- better resource utilization and environmental friendliness.
5.1.3 Economic aspects of use of trash fish/low-value fish in grouper farming in
Indonesia, Thailand and Viet Nam
This section summarizes a recent cost-benefit analysis by Sim (2006) for small-scale
grouper farming based on the use of trash fish/low-value fish and commercial feed in
three Asian countries. Feed was a major recurring cost throughout a single production
cycle. There were two main factors that determined the cost of feed: cost efficiency
and feeding effectiveness. In this study, an economic comparison between the use of
commercial pellet feed and trash fish/low-value fish was undertaken to reflect the
“true” economic benefits of the two feed types. The study dealt with: (i) the economic
efficiency of the feed as determined by the level of feed input and production output
and (ii) the corresponding CE for each grouper farm.(^5) CE = [ Total feed input (fed wet weight in kg] ÷ [ Biomass harvested – Biomass stocked (wet weight in
kg)]