Training Manual Application of Genetics and Biotechnology in ...

additional selection criterion. The genetically improved Salmon had improved feed
efficiency, early sexual maturity and the increased growth rate is mainly due to a
much higher feed intake per kg body weight. (Gjedrem et a1 2002).
The genetically improved strain GIFT (Genetically Improved Farmed Tilapia)
is an important example as to how genetic improvement can contribute to meet the
protein requirement of the people in five Asian countries such as Philippines,
Bangladesh, Vietnam, Thailand and Fiji Islands. The genetic gain for growth rate in
the GIFT project per generation across five generations of selection has been in the
range of 12-17%. Produ~tion trials and socio-economic surveys in these countries
revealed that the cost of production per unit of fish produced is 20-30% lower for the
GIFT strain than for the other Nile strains.(Gjedrem et a2 2002).
The AKVAFORSK is collaborating with the Columbian Government in a
genetic improvement project in the Pacific White Shrimp- Litopenaeus vannamei. A
breeding programme has been established for growth and White Spot Disease
Resistance.
Gitterle, (2005) reported that selecting for growth in Pacific White Shrimp will cause
a positive correlated response on overall survival. He also reported low genotrpe x
farm interaction for both traits. Resistance to WSSV and harvest weight is under
additive genetic control and thus would respond to selection.
In India, an Indo-Norwegian Collaborative project has been started in June
2004 on 'Genetic Improvement of Penaeus monodon (Tiger Shrimp) Through
Selection for Growth and White Spot Disease Resistance'. The collaborating
Institutions are Central Institute of Brackishwater Aquaculture, Chemai, Central
Institute of Fisheries Education, Mumbai and Institute of Aquaculture Research
(AKVAFORSK) Norway. This project envisages the rearing of 50 full-sib families of
Tiger Shrimp, obtaining data on growth rate as well as WSSV disease resistance.
Tagging is accomplished by Visible Implant Elastomer tags. The challenge tests are
conducted with individuals represented from each family. The survival data is
recorded and analysed along with the growth trait. The experiment is progressing at
CIBA, Chennai.
There has been considerable interest in 'Transgenic' fishes and shellfish. In
transgenesis, the fisNshellfish is modified genetically by introducing a gene taken
from some other source. This results in a geneticalb modzj?ed organism or GMO. As