The Tasmanian salmonid industry has recently been faced with several significant production issues necessitating increased use of antibiotics and antifoulants. The effects of these chemicals on the local ecology and ecosystem function are currently poorly understood and without evidence to the contrary, it is difficult for the industry to refute the perception that such chemicals have a detrimental effect on the environment.
There is a large body of literature regarding the effects of antibiotics, however the information pertaining to aquaculture is limited. Improvements in husbandry and vaccine development have now all but eliminated the use of antibiotics in aquaculture overseas, consequently there have been few recent aquaculture specific studies, with even fewer studies on ecosystem effects, the available information largely focussing on environmental persistence and antibiotic resistance. However, there is quite a lot of information in the terrestrial livestock and medical areas on the comparative effects of various antibiotics as well as quite a substantial ecotoxicological literature. In contrast there is a substantial local literature on the environmental impacts of antifoulants and heavy metals. There is a need for a targeted review to establish environmental risk factors associated with current antibiotic and antifoulant usage and to develop an appropriate strategy to research and monitor ongoing impacts.
Some data on sediment residue levels for both antibiotics and antifoulants has been collected by the salmon industry in compliance with drug/chemical licensing permit conditions authorities and by the state government in response to concerns regarding antibiotic usage. So far this data has not been collated and has only been subjected to preliminary analysis; a comprehensive evaluation of this data would markedly improve our understanding of current impacts and help to determine what additional information may be required.