Reducing mortality is economically important for the fish farmer and is equally important from an animal welfare perspective (AquaGen, 2006). The process of freshwater bathing invariably involves a level of fish mortality. Although the main determining factor of handling loss is the proportion of high gillscore fish in the population, there is evidence of resilience and susceptibility to handling events that may be independent of the level of gill pathology. Fish farmers are constantly refining techniques to minimise handling losses, but there is also a need to ensure that that animal welfare and sustainability can be incorporated in the breeding goal (Olesen, et al., 2000) allowing production of robust animals through selective breeding.
This project addresses various aspects of the TSGA TC 2011 R&D Strategy: (1) Fish Health (AGD)- Treatments; Selective breeding program; Epidemiology and pathobiology; Determination of what is actually killing fish; and (2) Production - Genetic health surveillance; Improving on-farm management. By helping to ensure that animal robustness is considered in the breeding goal, the project also relates to key aspects of the Seafood CRC Breeding for Profit theme (Strategy #1 Development and implementation of breeding programs for improvement of commercially important traits; Strategy #3 Appropriate application of emerging and complementary technologies and Strategy #4 Commercialisation strategies for genetics improvement in aquaculture). In addition, the animal welfare aspects of this project will assist in sustainable and ethical seafood production.
Final report
Amoebic gill disease (AGD) continues to have a significant economic impact upon production of sea-farmed Atlantic salmon in Tasmania. Reducing mortality is economically important for the fish farmer and is equally important from an animal welfare perspective. The process of freshwater bathing invariably involves a level of fish mortality. Although the main determining factor of handling loss is the proportion of high gill score fish in the population, there is evidence of resilience and susceptibility to handling events that may be independent of the level of gill pathology. Fish farmers are constantly refining techniques to minimise handling losses, but there is also a need to ensure that that animal welfare and sustainability can be incorporated in the breeding goal allowing production of robust animals through selective breeding.
The potential benefits of improved AGD resilience could be gauged on a number of levels. Disease resilience and decreased handling may potentially be worth $1.47 m to the industry.
Project Objectives
- Determine the level of genetic variation within the Saltas selective breeding program population associated with AGD handling resilience, and the opportunity and risk for selection for this trait
- Establish the level of genetic variation in the Saltas SBP population associated with cardiovascular traits and the opportunity and risk for selection of these traits
- Establish the level of genetic correlation between cardiovascular and AGD resilience traits
- Examine cost-effective and non-destructive resilience selection traits that can be applied to freshwater broodstock within the Saltas SBP
