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General introduction | 13
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natural food. Semi-intensive production systems are characterized by moderate for example, Genetically Improved Farmed Tilapia (GIFT) (Pullin et al., 1991; Eknath
input use, pond fertilization using manures or inorganic fertilizers to boost natural et al., 1993; Bentsen et al., 1998) and FaST(Bolivar, 1998), GenoMar Supreme
food production, use of supplementary homemade or commercial feed, higher Tilapia (Zimmermann and Natividad, 2004) and GET-EXCEL (Tayamen, 2004).
stocking density than extensive production systems, and Nile tilapia can be farmed Among the Nile tilapia selective breeding programs, the GIFT breeding program is
in monoculture or polyculture system. Earthen ponds without aeration are most the most important non-commercial breeding program. The GIFT project was 1
commonly used in both extensive and semi-intensive production systems. Absence started in 1988 in the Philippines and executed by the International Center for
of aeration results in recurrent high dissolved oxygen fluctuation during the day. Living Aquatic Resources Management (ICLARM), now WorldFish, in collaboration
Nile tilapia requires a normoxic environment (dissolved oxygen above 5 mg/L) for with partner organizations (Pullin et al., 1991). The base population was formed
optimal growth. However, tilapia are known to tolerate dissolved oxygen levels, from four wild stocks from Egypt, Ghana, Senegal and Kenya and four commercial
which often drop below 3 mg/L during nights. Nile tilapia strains farmed in the Philippines (Pullin et al., 1991; Gjedrem, 2012).
After six generations of selective breeding in the Philippines, WorldFish continued
Intensive production systems are characterized by high input use, high stocking the selective breeding of the GIFT strain in Kedah State, Malaysia, from generation
density, use of a nutritionally complete pelleted diet, use of continuous aeration for six after receiving 63 full sib groups of 35 fish each from the Philippines towards the
an optimized environment. Intensive Nile tilapia production is practiced in end of 2000 and the beginning of 2001 (Ponzoni et al., 2011b). Currently, the GIFT
raceways, cages and ponds. Extensive and semi-intensive production systems are strain has been selected for 20 generations in Malaysia and disseminated to more
probably the dominant production systems, but exact numbers are not available. than 16 countries worldwide (Agha et al., 2018; WorldFish, 2021).
Hereafter, both extensive production systems and semi-intensive production
systems are referred to as smallholder production systems. The Genetically Improved Farmed Tilapia (GIFT) breeding program benefited from
the experiences gained in salmon breeding that started in 1971 in Norway
(Gjedrem, 2012). Genetic gains in harvest weight ranging from 7-11% per
generation over four to six generations of GIFT breeding program have been
published (Khaw et al., 2008; Ponzoni et al., 2011a; Thodesen et al., 2011). After six
generations of selection, the GIFT strain grew up to 85% faster than the fish used in
the base population (WorldFish, 2021). The estimated selection response ranges
from 10 to 15% in the last ten generations (Khaw, 2015). Recently estimated
average selection response for GIFT strain was 7% for 17 generations, indicating
continued response to selection (Benzie et al., 2021). Data from breeding programs
conducted with other Nile tilapia strains by WorldFish in Abbassa, Egypt, indicate
that on average 3% selection responses have been achieved for 12 generations
(Benzie et al., 2021).
Other Nile tilapia selective breeding programs also reported considerable selection
responses. In China, on average 11.4% (range 7.4 to 18.7%) selection response was
Figure 1.1 World tilapia production from 1990 to 2019 (FAO, 2021). recorded for Progift Nile tilapia body weight (Thodesen et al., 2011). For GenoMar
Supreme Tilapia the average selection response over 11 generations was 17%
1.3. Nile tilapia selective breeding programs (Gulzari, 2017).
Many selective breeding programs have been established for Nile tilapia. Until
2005, seventeen breeding programs were established for Nile tilapia (Neira, 2010),
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