Fish as feed inputs for aquaculture: practices, sustainability and implications

16 Fish as feed inputs for aquaculture – Practices, sustainability and implications

3.1.3 Trash fish and other fishery by-products

In Asia in particular, trash fish or low-value fish are the main source of fish for use

in aquaculture. They are fed directly to fish in the form of a slurry or mash and are

distinct from the trash fish that are first converted into fishmeal.

Direct estimates of trash fish/low-value fish usage in aquaculture, either directly

and/or indirectly, are available only for Australia and Viet Nam. In the case of Viet

Nam, it was estimated that use of trash fish/low-value fish in inland aquaculture ranged

from 64 800 to 180 000 tonnes and in coastal aquaculture from 71 820 to 143 640

tonnes, and the total amount used in aquaculture in Viet Nam to be between 176 420

and 323 640 tonnes (Edwards, Le and Allan, 2004). The latter figures amount to

approximately 22 percent of all trash fish/low-value fish production in Viet Nam. The

main bulk of trash fish/low-value fish is used for production of fish sauce (Dao, Dang

and Huynh Nguyen, 2005). While anchovy is preferred for fish sauce production, it

is less popular for cage aquaculture, as it is difficult to store on ice because the flesh

is very soft and breaks down readily. Thus there is limited competition between fish

sauce production and cage culture in the Mekong Delta. In a recent survey conducted

in central Viet Nam (Phuc, 2007), the main reasons fish farmers choose to use trash

fish for aquaculture were low cost (77 percent of total households interviewed), ease

of purchase (31 percent), fast animal growth (62 percent) and lack of alternative feeds

(31 percent).

The Australian southern blue fin tuna (Thunnus maccoyii) fattening farming, based

on the on-growing of wild-caught young, is totally dependent on low-value/trash fish

as the sole feed source. In 2003, 5 409 tonnes of wild-caught tuna (average weight 15 to

30 kg) were fattened to 9 102 tonnes over a period of three to five months, fed solely

on pilchard and mackerel (EconSearch Pty Ltd, 2004). The approximate increase of

4 000 tonnes to fattened weight required 50 000 to 60 000 tonnes of imported feed – in

this instance trash fish/low-value fish (Allan, 2004), which is at best a food conversion

ratio of 12.5:1.

Estimations on projected needs of trash fish/low-value fish by the Asia-Pacific

region in the year 2010 suggest that the main growth phase of the mariculture sector

has already occurred and that most suitable areas for small-scale farming are already

utilized. In addition, the advances in seed production technologies have not progressed

TABLE 8

Raw material sources for fishmeal and fish oil in the European Union (EU-15), 2002

Country Feedfish

(tonnes)

Trimmings

(tonnes)

Proportion

of trimmings (%)

Denmark 332 000 33 200 10

United Kingdom 7 800 42 500 84

Spain 42 000 100

Sweden 18 750 6 250 25

France 25 000 100

Ireland 8 800 13 200 60

Germany 17 000 100

Italy 3 000 100

Total 367 350 182 150 33

Source: IFFO (2002)

(^3) EC Disposal, Processing and Placing on the Market of Animal By-products Regulations (SI 257, 1994);
EC Regulation No. 1774/2002 of the European Parliament and of the Council of 3 October 2002 lay
down health rules concerning animal by-products not intended for human consumption (recently
amended by Commission Regulation (EC) No. 808/2003 of 12 May 2003); and the Commission
Regulation (EC) No. 811/2003 on the intra-species recycling ban for fish.