Use of wild fish and other aquatic organisms as feed in aquaculture in the Asia-Pacific 109
with a shell length of 6 to 8 cm (Kritsanpuntu et al., 2005). In China, the harvesting size
ranges from 20 to 30 g per individual and a shell length from 4 to 6 cm.
Interestingly, in Babylon snail culture, which tends to involve small-scale, backyard
operations, the trash fish/low-value fish are often bought from the fish market and are
fish destined for human consumption, such as for example, in Thailand (Figure 19).
By contrast, in Viet Nam, the culture practices occur mostly outdoors in net pens, and
the stock is fed trash fish/low-value fish that is normally unsuited for direct human
consumption. The purchase of fish used for feeding is often done on a daily basis, and
the average conversion efficiencies range from 5:1 to 7:1.
5.6 Total direct use of trash fish/low-value fish in Asia-Pacific aquaculture
Using the data provided in the foregoing sections, an attempt was made to estimate the
total amount of trash fish/low-value fish used as a direct feed source in aquaculture in
the Asia-Pacific region. High and low predictions for the year 2010 were also estimated
based on the assumptions on production increases and changes in feed management
previously discussed (Table 18). Accordingly, in 2004 the usage of trash fish/low-value
fish in aquaculture in the Asia Pacific region is estimated to have ranged from
2 465 000 to 3 882 000 tonnes, and the corresponding low and high estimates for 2010
are 1 890 490 and 2 745 495 tonnes, respectively. Although the range in these estimates
is significant, nevertheless, they provide a figure that could be used in planning and
development activities that recognize the need to reduce the dependence of Asia-
Pacific aquaculture on trash fish resources.
FIGURE 19
Trash fish/low-value fish species used for Babylon snail culture. In some practices, the relatively
high-quality trash fish/low-value fish may be filleted, the fillets used for other purposes and the
frames fed to Babylon, which feed on the attached bits of flesh, leaving the frame cleanTABLE 18
The total use of trash fish/low-value fish as a direct feed source in Asia-Pacific aquaculture, based on
production estimates of the present study
Activity Country/region Gradea Quantity (thousand tonnes)
2004 2010a 2010b
Marine fishb Asia A, B 1 603–2 770^913 1 663
Southern bluefin
tuna
South Australia B 50–60 45 50
Freshwater fish Asia A, B 332 332 c 332 c
Crab fattening Asia B 480–720 600 750
Total 2 465–3 882 1 890 2 795
aGrade A – low grade, unsuitable for human consumption; Grade B – may be suitable for human consumption.
b2010 low and high predictions are based on increased production rates (10 and 20% increments) and associated changes in feed
management given in previous tables (Tables 10 and 11). For crabs, the predictions are based on an overall increase of 25%
production from the current levels and trash fish/low-value fish use calculated at conversion efficiencies of 4 and 5, respectively,
for two predictions (2010a and 2010b).
cPrediction is not attempted and the value of 2004 is used instead.