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J.G. Bell and R. Waagbø
Nowadays, the efficacy of n-3 HUFA in the prevention or modulation of many
of the inflammatory conditions prevalent in the developed world is well established
(Connor 2000). However, while the increased consumption of fish is widely
recommended, there is currently concern that the levels of persistent organic
pollutants (POPs) including dioxins, furans, polychlorinated biphenyls (PCB) and
polybrominated dephenylether (PBDE) flame retardants, as well as the presence of
toxic metals, including Pb, As, Cd and Hg, present a potential risk to human health
(Jacobs et al. 2002a; Hites et al. 2004a,b; MAFF 1999). In 2001, the EU introduced
new limits on dioxins and furans in fish feeds and fish for human consumption
(SCAN 2000; SCF 2001). These values were 2.25 ng dioxin toxic equivalents
(TEQ) kg
−1 in feed and 4.0 ng TEQ kg
−1 in fish. Currently, the EU has set limits for
the 12 dioxin-like (DL) PCBs, in addition to the values for the 17 dioxins/furans
assigned toxic equivalency factors, with combined values of 8 ng TEQ kg
−1 in fish
(EC, 2006a).
In this chapter we will discuss why there is a need to develop aquafeeds that are
less reliant on marine raw materials including the effects of including plant meals
and oils on the nutritional quality of farmed fish in terms of n-3 HUFA content, as
well as vitamin and mineral content. In addition, the importance of n-3 HUFA for
human health, current recommended intake levels of n-3 HUFA and the concentrations of n-3 HUFA and other nutrients provided by farmed fish will be discussed.
Finally, the concentrations of POPs in farmed fish, as well as mechanisms by which
these concentrations can be reduced by manipulation of feed ingredients will be
discussed.
6.2 Why Do We Need Alternatives to Fishmeal and Fish Oil?
Food-grade capture fisheries have maintained a fairly stable supply over the last 20
years, although increasing demand has meant that the shortfall in sea food
availability for human consumption has been met by increasing aquaculture production (Tidwell and Allan 2002; FAO 2005). In 2003, production of Atlantic
salmon and marine-cultured rainbow trout in Europe was ~824,000 t with bass and
bream contributing ~150,000 t (FAO 2005). Salmonids are the biggest consumers
of extruded aquafeeds in Europe and to produce this tonnage of fish required over
1 million tonnes of extruded feed (Tacon 2005). In 2003, aquaculture utilised 79%
of global FO production and 42% of FM production and, of this, salmonid culture
used 52 and 27% of FO and FM production, respectively (Tacon 2004).
Therefore, as the supplies of FO and FM have remained static at ~6 million
tonnes and ~1 million tonnes per annum, respectively, for around 20 years, the
continued increased demand for these products for aquaculture is unsustainable. It
is therefore vital that reliance on marine raw materials is reduced and that sustainable aquafeeds are developed using more terrestrial plant products.
In addition to a potential shortfall in the supply of FM and FO, concerns have
recently been raised regarding the sustainability and ethical arguments for utilising
J.G. Bell and R. Waagbø
Nowadays, the efficacy of n-3 HUFA in the prevention or modulation of many
of the inflammatory conditions prevalent in the developed world is well established
(Connor 2000). However, while the increased consumption of fish is widely
recommended, there is currently concern that the levels of persistent organic
pollutants (POPs) including dioxins, furans, polychlorinated biphenyls (PCB) and
polybrominated dephenylether (PBDE) flame retardants, as well as the presence of
toxic metals, including Pb, As, Cd and Hg, present a potential risk to human health
(Jacobs et al. 2002a; Hites et al. 2004a,b; MAFF 1999). In 2001, the EU introduced
new limits on dioxins and furans in fish feeds and fish for human consumption
(SCAN 2000; SCF 2001). These values were 2.25 ng dioxin toxic equivalents
(TEQ) kg
−1 in feed and 4.0 ng TEQ kg
−1 in fish. Currently, the EU has set limits for
the 12 dioxin-like (DL) PCBs, in addition to the values for the 17 dioxins/furans
assigned toxic equivalency factors, with combined values of 8 ng TEQ kg
−1 in fish
(EC, 2006a).
In this chapter we will discuss why there is a need to develop aquafeeds that are
less reliant on marine raw materials including the effects of including plant meals
and oils on the nutritional quality of farmed fish in terms of n-3 HUFA content, as
well as vitamin and mineral content. In addition, the importance of n-3 HUFA for
human health, current recommended intake levels of n-3 HUFA and the concentrations of n-3 HUFA and other nutrients provided by farmed fish will be discussed.
Finally, the concentrations of POPs in farmed fish, as well as mechanisms by which
these concentrations can be reduced by manipulation of feed ingredients will be
discussed.
6.2 Why Do We Need Alternatives to Fishmeal and Fish Oil?
Food-grade capture fisheries have maintained a fairly stable supply over the last 20
years, although increasing demand has meant that the shortfall in sea food
availability for human consumption has been met by increasing aquaculture production (Tidwell and Allan 2002; FAO 2005). In 2003, production of Atlantic
salmon and marine-cultured rainbow trout in Europe was ~824,000 t with bass and
bream contributing ~150,000 t (FAO 2005). Salmonids are the biggest consumers
of extruded aquafeeds in Europe and to produce this tonnage of fish required over
1 million tonnes of extruded feed (Tacon 2005). In 2003, aquaculture utilised 79%
of global FO production and 42% of FM production and, of this, salmonid culture
used 52 and 27% of FO and FM production, respectively (Tacon 2004).
Therefore, as the supplies of FO and FM have remained static at ~6 million
tonnes and ~1 million tonnes per annum, respectively, for around 20 years, the
continued increased demand for these products for aquaculture is unsustainable. It
is therefore vital that reliance on marine raw materials is reduced and that sustainable aquafeeds are developed using more terrestrial plant products.
In addition to a potential shortfall in the supply of FM and FO, concerns have
recently been raised regarding the sustainability and ethical arguments for utilising