A risk assessment for managing non-native parasites

Abstract

The spread of non-native parasites with the movement of animals is a primary cause of disease emergence worldwide. Such introductions can threaten native biodiversity, hinder conservation efforts and limit the socio-economic development of natural resources. Evaluating the threats from alien parasites can represent a considerable challenge, due to the limited information that often accompanies their introduction. We present a comprehensive modular risk assessment scheme that supports the management of non-native fish parasites in their pre- and post-introduction phases. This scheme addresses some of the shortcomings of current risk analysis, including the risk management of non-notifiable pathogens and impact assessment of parasites following establishment. An initial procedure for hazard identification promotes a rapid assessment of disease risk and prompt imposition of management measures. This is followed by a longer-term assessment of impact that accommodates available and emerging knowledge on the pathogen and its distribution. Consideration is given to ecological and economic consequences of disease at the host, population and fishery levels. Each module provides an easily interpreted output that underpins management responses, ranging from monitoring parasite distribution to their attempted eradication. A final module ensures clear communication of disease risk to relevant stakeholders, using the other modules as a framework. Outputs of this risk assessment will inform the prioritisation of available resources and provides a scientifically robust foundation on which to base practical and proportionate management measures to protect native environments. The scheme presented here was specifically developed for freshwater fisheries in England and Wales, but may be modified for use globally and for the non-native parasite fauna of other taxa

Parasites of non-native freshwater fishes introduced into England and Wales suggest enemy release and parasite acquisition

“…Hockley et al 2011;Reading et al 2011). However, examples of serious disease outbreaks following the translocation of monogenean parasites, such as Gyrodactylus salaris (Bauer et al 2002;Bakke et al 2007), highlights the importance of continued monitoring and prompt risk assessment to inform management (Williams et al 2013). There was no evidence that parasite spillover had occurred in any of the studied fish communities in the introduced range, with no recordings of the introduced parasites in the sympatric native fishes.…”

“…Whilst fish introductions in England Wales are routinely screened for certain 'notifiable' diseases before release (at least where introduction is intentional and approved; Davies et al 2013), there is arguably a requirement for increased parasite screening for introductions of non-native fish. However, with differing legislative, economic and political drivers, managing the introduction and spread of non-native pathogens represents a complex global challenge (Williams et al 2013). Although we found few examples of non-native fish pathogens being imported directly on seven nonnative fishes, Phillips et al (2010) found that, whilst initially an invasive species may experience parasite release, those that do remain-even in low abundance-might re-establish, having consequences on both the non-native host and the wider fish community.…”

“…When free-living species are introduced then their parasite fauna can also be introduced (Williams et al 2013). These parasites then potentially spill-over into native species, with the potential that resistance and tolerance of these new hosts to infection will be low (Torchin et al 2003;Kelly et al 2009).…”

Comparative population genetics of two invading ticks: Evidence of the ecological mechanisms underlying tick range expansions

“…The spread of parasites is a major source of disease emergence for vertebrate taxa, including humans (George 2008, Mack et al 2000, Williams et al 2013). Climate change and anthropogenic landscape alterations, such as fragmentation and suburban sprawl, have been linked to tick range expansions worldwide, resulting in changes to tick community structure and altered tick-borne pathogen dynamics (Childs and Paddock 2003, Cumming and Van Vuuren 2006, Gage et al 2008, George 2008, Léger et al 2013).…”

Lernaea cyprinacea (Crustacea: Copepoda) in the Iberian Peninsula: climate implications on host–parasite interactions

“…Quiroz-Martínez and Salgado-Maldonado, 2013;Scholz and Choudhury, 2014). That said, future monitoring programmes still need to take into account parasite protocols in order to improve the knowledge about distribution, disease threats, epidemiology and spatiotemporal variation of non-native parasites in nature (Williams et al, 2013). Additionally, other management actions can be pursued to diminish the effects of non-native parasites such as eradication and control programmes of either hosts or pathogens (e.g.…”