Principles of Genetics and Breeding

13.1.6. History of selective breeding programme in aquaculture

Breeding programs are rare in aquaculture.

• As early as in 1920s, Embody and Hyford (1925) selected surviving brook trout (Salvelinus fontinalis) from a population with endemic furunculosis and increased the survival rate from 2% in the initial population to 69% after three generations of selection.
• Donaldson began breeding work with rainbow trout in 1932 and reported significant increase in growth and fecundity. Donaldson and Olson (1955) reported the historical achievement by producing the “Donaldson” strain of rainbow trout (Oncorhynchus mykiss). After more than 35 years of directed individual selection, this strain of rainbow trout was appreciated by trout culturists in the USA and throughout the world and has been widely distributed. In spite of these pioneering success, very little selective breeding research was conducted in aquacultured species prior to 1970.
• In the mid 1960’s, two large-scale directed selection efforts were initiated in the common carp. Moav and Wohlfarth’s (1976) mass selection programme, initiated in 1965, did not result in any improvement in growth rate. A long term programme for selecting common carp resistant to dropsy, a serious infectious disease, for farming was initiated (Kirpichnikov,1993). The breeding programme consisted of selection within the local and the Siberian wild carps from the river Amur, and crossing between them. Mass selection for resistance to dropsy and for high growth rate was carried out. The selection programme was successful and resistance to dropsy has been improved. As a result of this successful breeding programme, three stocks of Krasnodar common carp were developed, and heterotic crossbreds among them are used for commercial production in that region and other parts of the former Soviet Union.
• In Norway, AKVAFORSK started an extensive breeding experiment with Atlantic salmon and rainbow trout in 1971. Four years later it developed into a breeding program aimed at selection for growth rate. By 1985 the program had been transformed into a national breeding program run by the salmon and trout producers. The following traits were considered for selection, body weight at marketing; Low frequency of early maturation; disease resistance, challenge test against furunculosis and flesh quality, fat %, fat distribution and flesh colour. Genetic gains of 13% for salmon and 14.4% for trout have been reported.
• In 1993, The Philippines National Tilapia Breeding Programme was started with broodstock from the GIFT (Genetic Improvement of Farmed Tilapia) programme. Selection for increased growth in GIFT Nile Tilapia resulted in 77 percent to 123 percent growth improvement. The genetic gain was superior to results from crossbreeding experiments. The 11 percent genetic gain per generation in GIFT tilapia is better than that obtained in most other species of fish.
• To improve the Rohu (Labeo rohita) through selective breeding and cross breeding, a collaborative research project between CIFA, India and AKVAFORSK (Institute of Aquaculture Research), Norway was initiated in 1992. Fingerlings of Rohu from different rivers in India were brought to CIFA and served as base populations for the development of genetically improved stock of Rohu for farming.

Several large scale selection experiments and breeding programmes, aiming at increasing growth rate, were conducted more recently in various species, resulting in 10-20% gain per generation. The species details and the countries involved in selective breeding are presented in Table 1.

• Coho salmon selected for growth rate over 4 generations produced an average response of 10.1% per generation.
• With respect to body weight, a 30 percent increase in rainbow trout was achieved within six generations of selection.
• In Atlantic salmon, an increase of seven percent was achieved within a single generation and an increased growth rate of 50 percent was achieved within ten generations in coho salmon.
• In channel catfish, genetic gain of 12-18% and 20% has been obtained.
• These estimates of genetic gain in growth rate vary 10.1% to 23% per generation, which is much higher than what is common in farm animals.
• Domestication and selective breeding of the Kuruma shrimp Penaeus japonicus in Australia commenced in 1993. Following the success of these trials, there has been a progressive increase in the use of selectively bred stocks. Up to 75% of farm ponds stocked with genetically improved stocks.
• A prawn farming company pioneered commercial scale selective breeding of the banana shrimp P. merguiensis in Australia. The use of domesticated selectively bred stocks now accounts for the majority of farmed P. merguiensis production in Australia. The brown tiger prawn P. esculentus has also been successfully domesticated and selectively bred stocks are now being used in farming. The last decade has seen the initiation of many new local and/or national breeding programmes in a range of countries and species.

Table 1. The species details and the countries involved in selective breeding.

Species	Countries
Coho salmon	Chile
Atlantic salmon	Chile, Iceland, Ireland and Scotland
Rainbow trout	Chile, France and the USA
Brown trout (Salmo trutta)	France
Oreochromis shiranus	Malawi
Multi – species tilapia hybrid, Gilthead sea bream (Sparus aurata), Mediterranean sea bass (Dicentrarchus labrax)	Israel
Channel catfish	USA
Turbot (Scophthalmus maximus)	Norway and Spain
Rohu (Labeo rohita)	India
Common carp	China, the Czech Republic, Estonia, Russia and Vietnam
Blunt snout bream (Megalobrama amblycephala	China
Tench (Tinca tinca)	the Czech Republic
Pacific oyster (Crassostrea gigas)	Australia, USA
Sydney rock oyster (Saccostrea glomerata), P. japonicus, P. esculentus and P. merguiensis	Australia,
White Pacific Shrimp (Litopenaeus vannamei)	Brazil, Colombia, Mexico and the USA
Penaeus stylirostris	Mexico
P. monodon	Australia, Thailand and the USA

The selection response for growth rate in species which have been under selection is presented in Table 2. The genetic gains reported are all within a range of 10-23 % per generation.

Table 2. Selection response for growth rate

Species	genetic gain%/ generation	No.of gen.	Reference
Channel catfish	20	1	Bondar (1993)
Channel catfish	12-18	1	Dunham (1987)
Coho Salmon	10	4	Hershberger et al.(1990)
Atlantic salmon	14	1	Gjerde (1986)
Rainbow trout	13	2	Gjerde (1986)
Tilapia	15	2	Jarimopas (1986)
Tilapia	23	1	Eknath (1993)
Tilapia	14-17	5	Eknath (1998)

Source:Refstie et al. (1999)