Global agricultural food production relies on the benefits gained from many generations of selective breeding, and the vegetables, cereals and livestock we eat today are vastly more productive than the wild species our distant ancestors first domesticated.
Similar benefits are beginning to become apparent in the field of aquaculture, where recent advances in production techniques, feed technology and genetics, have helped to increase production of farmed fish and shellfish from around 5 million metric tons (MT) in 1970, to more than 50 million MT today.
However, it is genetic selection — not to be confused with genetic modification — which holds the most promise for improving growth rates and disease resistance, and for answering our future food security needs.
According to scientists, only 20 percent of the world’s seafood raised in aquaculture is currently based on genetically improved stocks, so there is definitely room for improvement.
They predict that through genetic selection, total production of both existing and emerging species could be increased by up to 40 percent, with better quality, faster growing fish that are more efficient at converting feed. Meeting all three criteria is essential if the costs of production are to be lowered and the consumer provided with a product of attractive quality and price.
Atlantic salmon has seen the greatest improvements in recent years, and is the only species to be 100 percent bred from improved stock based on family selection. Professor Trygve Gjedrem, the ‘father’ of selective breeding in aquaculture, believes that more needs to be done to encourage greater efforts in genetic advancement in other species, but said that political will and regulatory changes are needed to make it worth investing in the future.
“Genetic gain can be dramatic and exciting in fish, because we can double the growth rate in 5-6 generations, and improve the food conversion ratio by 4 percent per generation,” he said.
“This is tempered by the life-cycle of the fish, with each salmon generation taking 4 years, making it 24 years to double the growth rate. A tilapia generation takes just 1 year, and the common carp generation interval is 2 years, so these fish, which are important species in developing countries, can be improved a lot faster,” he said.
The Genetic Improvement of Farmed Tilapia (GIFT) project run by the WorldFish Center and partners in the late 1990s resulted in a strain of fish that is still used today in Asia, Africa and Latin America. Local breeding programs for species such as carp, freshwater prawns, rohu and silver barb also benefit from the selection techniques developed by the project.
Gjedrem explained that before GIFT, most tilapia were slow growing and harvested at a small size, but the new strain was fast growing and high yielding.
“Suddenly farmers could grow tilapia up to 700-800 grams in the same timeframe, and produce a fish that could be filleted. This opened up new markets that also needed a processing industry to furnish them,” he said.
In the U.K., Landcatch has made a major breakthrough in breeding sea lice-resistant salmon, thanks to the use of state-of-the-art genetics technology based on SNP chips, which are genomic selection tools that allow scientists to pinpoint inherited traits in individual fish DNA. This has importance not just for the health and wellbeing of the fish, but also for the image of salmon in the eyes of environmental NGOs and consumers.
In Chile, which is responsible for 90 percent of the world’s production of farmed Coho salmon, Dr. Roberto Neira of the University of Chile in Santiago, is working with companies to improve quality traits such as fillet colour and fat content, as well as growth rates and disease resistance. He is also involved in tilapia breeding programs in Costa Rica, Ecuador and Brazil.
Neira is excited about the potential for improving aquatic animal species, and pointed out in his 2010 paper “Breeding in Aquaculture Species: Genetic Improvement Programs in Developing Countries,” that great opportunities exist to improve the hundreds of species already cultured in aquaculture, yet 85 percent of the world’s breeding programs concentrate on tilapia, carp and shrimp.
Shellfish production can also benefit from genetic improvement and in New Zealand, scientists at the Cawthron Institute have successfully bred mussels with a number of improved traits including strength, survival, taste and appearance/color.
Shellfish program manager Nick King explained that some markets prefer the bright orange color of female mussels and the ability to produce an all-female crop means that mussel farmers can meet market demand for these.
“Our research is now being taken up to commercial scale with a pilot project for the Greenshell mussel industry at the Cawthron Aquaculture Park by Shellfish Production and Technology New Zealand, which aims to produce enough seed with the correct traits for a 30,000 MT harvest by 2019,” he said.
Given the rate of advance that has been seen over recent years, and the improved selection tools that are now becoming available, it should be possible to look optimistically at the potential for aquaculture to expand to meet the growing world demand for protein.
