Improving productivity in aquaculture by promoting natural disease resistance in fish
Project description and benefits
The reduction of incidents of disease in aquaculture is a primary concern of the industry. Disease defence strategies have in the past focused largely on hygiene regimes and the use of pharmaceuticals. An increasingly important area of prevention lies in the natural ability of the fish itself to resist disease. Different species and strains of fish vary significantly in their susceptibility to disease and a major factor in this variation is the genetic make up of the fish. This project seeks to establish reliable indicators for selecting fish, on the basis of their genetic constitution, that are naturally resistant to disease. These genetic ‘markers’ would facilitate selective breeding programmes and assist aquaculture producers develop stocks of robust fish with enhanced disease resistance
Services provided by Cefas
The project methodology involved seeking a genetic marker associated with disease resistance. Rainbow trout and viral haemorrhagic septicaemia (VHS) were used as the model species and disease. The interrelationship between disease susceptibility and response of the fish to stress, measured by the concentration of the hormone cortisol in the blood, was also investigated. The project made use of Cefas state of the art aquarium facilities.
The process of identifying suitable genetic markers was undertaken by:
- Identifying strains of rainbow trout that show natural resistance to VHS.
- Screening the genomes of selected resistant and susceptible fish strains using a DNA pooling strategy and published microsatellite markers for rainbow trout.
- Using broad-scale quantitative trait locus (QTL) mapping to enable identification of linkage of markers to disease resistance.
By following on from this work with high-resolution QTL mapping, genes associated with disease resistance may be identified and used in future selective breeding programmes.
