Potential environmental impacts from farming rainbow\ud trout using inland saline water in Western Australia

Secondary salinisation, caused by rising water tables as a result of land clearing, has led to large areas of unproductive agricultural land in Australia. Throughout the Western Australian wheatbelt, there is interest in the culture of rainbow trout (Oncorhynchus mykiss) and other fish species using saline groundwater on salt-affected farmland. We surveyed farmers and interviewed representatives of resource management agencies, to determine potential environmental impacts associated with this form of aquaculture. Four types of culture units have been used to grow trout: farm dams, constructed ponds, natural lakes and tanks. Our analysis of their water flow characteristics suggests that dams, ponds, lakes and tanks are likely to produce qualitatively similar environmental impacts. Farmers and resource managers identified the same potential environmental impacts from inland trout farming, but their perceptions of the importance of these impacts differed. In general, farmers ranked on-farm impacts more hihgly than off-farm impacts, while the reverse was true for resource managers. The regulation of environmental impacts in inland saline aquaculture is comlicated by the diversity of government agencies involved and by the small scale of the industry. This suggests that economic instruments, facilitated by the voluntary development and application of environmental management guidelines, might be a better management tool than regulation, but there is a need to more precisely define and internalize many of the external environmental costs