Medidas de Gestao das Pescarias Marinhas e Aquicultura 2019 The State of World Fisheries and Aquaculture 2018 | Page 162

PART 3 HIGHLIGHTS OF ONGOING STUDIES
increasingly replaced by crops, especially oilseeds
(Tacon, Hasan and Metian, 2011; FAO, 2012d;
Hasan and New, 2013; Little, Newton and
Beveridge, 2016). Fishmeal and fish oil inclusion
rates in Atlantic salmon diets, for example, fell
from 65 to 24 percent and from 19 to 11 percent,
respectively, between 1990 and 2013 (Ytrestøyl,
Aas and Åsgård, 2015). Food conversion ratios
(the ratio of biomass of food fed to fish produced)
over the past 25 years have fallen from around 3:1
to around 1.3:1 (GSI, 2017), largely because of
better feed formulations, feed manufacturing
methods and on-farm feed management.
termed “semi-intensive aquaculture”) or to
supply all the farmed aquatic animal’s nutrition
needs (“intensive aquaculture”). The trend
towards increasing use of feed is driven by
greater availabilit y and by profitabilit y (i.e. with
profits increased by judicious use of feed). Thus,
between 1995 and 2015, production of industrial
aquaculture feeds increased sixfold, from 8 to 48
million tonnes (Figure 43) (Tacon, Hasan and
Metian, 2011; Hasan, 2017b).
Aquaculture feeds are manufactured from a variety
of crops and crop co-products, wild fish and fish
and livestock processing co-products. Some of
them, such as fishmeal and fish oil, are produced
from reductions of highly nutritious wild fish.
However, the proportion of fish from capture
fisheries being reduced to fishmeal and fish oil has
been declining in recent decades, and it is projected
that a growing share of fishmeal and fish oil
production will be obtained from fish processing
co-products (see “Projections of fisheries,
aquaculture and markets” in Part 4).
Although the use of fishmeal and fish oil in
aquafeeds is more prevalent among higher
trophic level finfish and crustaceans, low trophic
level finfish species or groups (e.g. carp, tilapia,
catfish, milkfish) are also fed with fishmeal and
fish oil at rates of 2 to 4 percent of their diets. In
total usage terms, the largest consumers of
fishmeal in 2015 were marine shrimp, followed by
marine fish, salmon, freshwater crustaceans, fed
carp, tilapia, eel, trout, catfish and miscellaneous
freshwater fish and milkfish (Tacon, Hasan and
Metian, 2011; Hasan, 2017b).
The dietar y inclusion rates of fishmeal and fish
oil in aquaculture feeds have also been falling,
FIGURE 43
SHARE OF CONSUMPTION OF TOTAL AQUACULTURE FEED BY SPECIES GROUP, 1995–2015 (%)
FRESHWATER
CRUSTACEANS
5% 5%
TROUT
2%
OTHERS
4%
2% 4%
31%
MARINE FISH
8% 8%
CARP
31%
7%
11%
SALMON
7%
CATFISH
11%
SHRIMP
15%
TILAPIA
17%
17%
15%
SOURCE: Updated from Tacon, Hasan and Metian, 2011
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CARP
CARP
TILAPIA
TILAPIA
SHRIMP
SHRIMP
CATFISH
CATFISH
SALMON
SALMON
MARINE FISH
MARINE FISH
FRESHWATER CRUSTACEANS
FRESHWATER CRUSTACEANS
TROUT
TROUT
OTHERS
OTHERS