Qualitative risk assessment of the effects of shellfish farming on the environment in Tasmania, Australia

Community concerns about the detrimental effects of shellfish farming on the environment have been increasing over the last decade in many shellfish producing countries, including in Tasmania, Australia. Environmental effects of shellfish farming can be assessed and managed using risk management processes, which have been developed for a wide range of human activities. In this study the risk of shellfish farming activities having detrimental impacts on the ecology of the Tasmanian marine environment was assessed using standard risk assessment methodology. This was based on local environmental information and on the level of production, stocking densities, and known husbandry practices in Tasmania compared to farm operations and levels of impact observed in other countries. The risk management process used in this study appears to be applicable to a variety of aquaculture activities. alitative risk assessment of detrimental impacts of shellfish farming rated the risk of spread of introduced pests and/or pathogens as high. However, this high risk rating would also apply to many other activities in the marine environment, such as commercial and recreational fishing and sea transport. The level of risk due to habitat disturbance was rated as moderate within the lease area, but would not be expected to extend outside the farm. Risks of organic enrichment of the seabed and reduced food resources for other filter feeders were both rated as low.