Averting the threat of alien aquatic species By accident or introduction, the arrival of an alien species can be damaging to the environment. New proposals are being drawn up to limit this threat to our aquatic ecosystems, already endangered from pollution, climate change and over-fishing. Health © Shutterstock Expansion in aquaculture has brought about many benefits, not least the increase in production for the seemingly insatiable demand for fish. One not quite so desirable effect is the rise in introduction of species normally non-indigenous to the area. Of course, there is always the chance that non-native fish may be of benefit but the arrival of alien species can change the local environment, habitats and ecology, sometimes for the worse. Either way, there is a need for an overall environmental and economic assessment of the importance and impact of aquaculture-related, non-indigenous species and guidelines to minimise any detrimental effects. The 'Environmental impacts of invasive alien species in aquaculture' (Impasse) project addressed concerns regarding the impacts of non-native and locally absent species in aquaculture. Chief among the objectives was the development of sound environmental practices and the formulation of quarantine guidelines. To make sure managers were equipped to propose mitigation measures for minimisation of adverse effects, a review of alien species in aquaculture was first drawn up. The information was entered into a database to underpin the development of protocols and guidelines. For assessment of risks from alien introduction a scheme for evaluation of the risks was developed using a modular framework approach accessible through the project website. Impasse prepared a report on quarantine procedures for several invasive species so as to limit associated pathogens. Recommendations from the extensive Impasse study include the introduction of regulations to accompany strategies proposals for the implementation of a complete regulatory framework. A website and training sessions have disseminated this information widely. Impasse has also planned conferences to extend beyond the lifetime of this valuable project – to continue the work and prevent unnecessary damage to our aquatic ecosystems.