94 Fish as feed inputs for aquaculture – Practices, sustainability and implications
Estimates of projected needs for trash
fish/low-value fish in 2010, based on
increases of 10, 15 and 20 percent over
the production levels obtained in 2004,
with corresponding decreases in the
proportion of each major group of finfish
fed on trash fish/low-value fish and a
marginal improvement in conversion rates
resulting from better feed management,
are given in Table 11 and Figure 14.
The projected increases in production
are retained at rather conservative levels
for a number of reasons. The main
growth phase in the mariculture sector
is believed to have already occurred,
and most suitable areas for small-scale
farming (which is the norm in Asia) are
mostly saturated already. In addition,
advances in seed production technology
have not progressed as expected, with,
for example, a survival rate for
grouper species of only 10 to 15 percent
at best (Rimmer, McBride and Williams,
2004). Finally, the ethical aspects of using trash fish/low-value fish for fish feed instead
of directly for human food are likely to remain a bone of contention and possibly a
limiting factor for aquaculture. In this context, it is important to point out that offshore
cage culture of carnivorous fish has not expanded significantly in Asia over the last
decade or more, even though it has been suggested as a potential growth area. Although
plausible reasons for this trend have been dealt elsewhere, one factor that is often not
taken into account is the relative unsuitability of the hydrographical conditions in
most offshore areas in Asia (De Silva, Phillips and Mohan, 2007). Figure 14 portrays
a projection of the use of trash fish/low-value fish as fish feed in the year 2010. The
amount used will be significantly lower than that reported for 2004, a situation similar
to that expected for the use of fishmeal in Asian aquaculture.5.1.2 Trash fish/low-value fish use in finfish mariculture in Indonesia, Peninsular
Malaysia, Viet Nam and China^4
Indonesia
In Indonesia, four locations (i.e. Lampung, Situbondo, Bali Island, and Batam) were
surveyed and conversion efficiencies of trash fish and commercial feed for various
marine species are presented in Table 12. Most marine fish farms in the Lampung area
produce grouper species. Trash fish/low-value fish use accounts for about 70 percent
of the total feed inputs in these farms. The cost of trash fish averages about 40 percent
of the total operating costs, ranging from 25 to 65 percent. The farmers’ perception
is that trash fish are cheaper and easy to obtain, and that stocks perform better than
when commercial feeds are given. Trash fish are also the main food source used in
barramundi (Asian seabass) as well as grouper farming in Situbondo. The daily trash
fish/low-value fish usage for a 15-pond (5 000 m^2 ) production system is around
150 kg/pond/day for fish weighing more than 500 g. The estimated CE for seabass in
ponds is around 6.0, while CE for groupers varies between 7.2 and 8.4. In Batam, trash(^4) This section is based on the findings of Sim (2006) except that of China. Information of China have been
extracted from Xianjie (2008)
FIGURE 14
Changes in the estimated trash/low-value fish usage in
marine and brackishwater finfish culture in Asia at two
conversion efficiencies of 6:1 and 10:1
0
500
1 000
1 500
2 000
2 500
3 000
1995 2004 2010a 2010b 2010c
6:1 10:1
Thousand to n n e s
Source: The 2010 values are based on increases in production (based on
information extracted from Tables 9 and 11)
Note: a, b and c denote three estimates for use of fishmeal for 2010. They
are based on a projected production increase from 2004 to 2010 of 10, 15
and 20 percent