In the field of applied breeding programmes we combine traditional breeding techniques with new knowledge about genetics and the genome. We use and develop knowledge and techniques such that fish breeders can improve key properties of species in the aquaculture industry in an efficient manner.
The term “breeding” describes the planned selection of individuals to become parents of the next generation of farmed fish, which in this way become better adapted and achieve higher performance.
Our scientists have participated in the start up and further development of breeding programmes for many species around the world. The breeding programmes for the Atlantic salmon, which is farmed in Norway, are probably the most advanced programmes in the world. Our scientists have been central in the start up and development of several of these breeding programmes, from the start of the Norwegian aquaculture industry until today.
The focus of breeding programmes is to improve the use of economically important resources in the aquaculture industry through, for example, shorter production times. The production time becomes shorter if the salmon grow more rapidly. Costs for personnel, feed and the keeping of fish in tanks and cages are also reduced.
Species in aquaculture, both of fish and shellfish, have properties that can be emphasised by culture in order to improve the use of resources. When such properties are selected to be part of a breeding programme and given priority, we say that they are a component of the breeding objective.
The properties that are included in the breeding objective can be given priority according to their expected economic significance. The breeding objective may contain several properties, but the effect of breeding on an individual property will be greater than is the case when breeding is carried out focussing on several properties at the same time. A common combination of properties in a breeding objective for salmon today is increased growth, improved resistance to disease, high quality of products, and delayed sexual maturation. It is possible to consider also other values that are not of commercial value in the market today, but that are, or may come to be, important for the industry, the environment or society in general.
Examples of such common and societal values are the ethical values of improved fish welfare and the environmental benefits of farmed salmon that have a greater resistance to disease and salmon lice. It is now possible to adapt salmon to different markets. If consumers are willing to pay more for, for example, leaner salmon, we can, in collaboration with breeding companies, adapt the farmed salmon to the needs of the consumers, to a large extent. Norwegian pork is a good example of this, where the thickness of the fat layer has been reduced by breeding from 30 to 10 mm, in accordance with the wishes of consumers.
Background knowledge for breeding
The knowledge that forms the basis of everything we do at Nofima in the fields of breeding and genetics comes from quantitative genetics and genomics. We combine these two disciplines at Nofima, and we have experienced that this combination is of great value in today’s practical work of breeding and for the further development of breeding programmes.
Quantitative genetics deals with the inheritance of properties that have a continuous range of variation (such as the growth of the fish), in contrast to categorical properties (such as blood type). It is often assumed that an individual property is influenced by a large number of genes, each one of which has a small effect on the property. Together with environmental influences, this results in variation between individuals and a normal distribution of the property. Quantitative genetics is based on the measurement of properties of an individual fish, and does not require knowledge about the particular genes that it carries. When we want to breed for properties where it is necessary to slaughter the fish in order to measure the properties (such as slaughter properties), it is, for example, siblings of the potential breeding fish that are measured.
Examples of properties that have been extremely successfully treated by selection programmes based on quantitative genetics are increased growth and a reduction in premature sexual maturation.
While traditional family-based breeding programmes use only information about properties that are recorded for siblings, genomics makes it possible to use also genetic information about a particular individual, for many properties. With the aid of genomics, we can also select the best candidates for breeding within one family, in addition to using results for sibling groups as in family-based selection. This can also give more reliable selection, and we can in this way achieve greater breeding success.
Most properties that are subject to breeding are, as previously mentioned, determined by several genes, where an individual gene has only a small effect. Some genes, however, have greater effects than others, and one individual gene may be able to explain much of the variation in the property. It is possible to locate such “high-effect genes”, also known as “QTLs” (which is an abbreviation for “quantitative trait loci”) with the aid of methods in genomics. Various methods are used, but they all have in common that they attempt to discover and use relationships between the properties of the fish and the gene variants that the fish possesses.
One example of a breeding programme in which genomic selection (selection based on genomic information) has been used is resistance to disease. Our work with the salmon disease IPN (infectious pancreatic necrosis) in collaboration with actors in the industry has contributed to the incidence of the disease being reduced by 75% in just a few years.
Our experience from work with breeding and genetics in a number of species of fish and shellfish all over the world in various production forms, and our close association with breeding expertise in animal husbandry, make us reliable partners for collaboration.