Management of Biological Invasions (2018) Volume 9, Issue 4: 475–482 DOI: https://doi.org/10.3391/mbi.2018.9.4.10 © 2018 The Author(s). Journal compilation © 2018 REABIC This paper is published under terms of the Creative Commons Attribution License (Attribution 4.0 International - CC BY 4.0) Proceedings of the 20th International Conference on Aquatic Invasive Species Management in Practice Rapid response achieves eradication – chub in Ireland Joe Caffrey1,2,*, Kevin Gallagher3, Dermot Broughan2 and Jaimie T.A. Dick4 1Inland Fisheries Ireland and 2INVAS Biosecurity Ltd, 82 Lakelands Close, Stillorgan, Co Dublin, Ireland 2Inland Fisheries Ireland, Ashbourne Business Park, Dock Road, Limerick, Ireland 3Agri – Food and Biosciences Institute, 18A Newforge Lane, Belfast, BT9 5PX, U.K. 4School of Biological Sciences, Queen’s University Belfast, MBC, 97 Lisburn Road, Belfast BT9 7BL, U.K. Author e-mails: [email protected] (JC), [email protected] (KG), [email protected] (DB), [email protected] (JD) *Corresponding author Received: 28 February 2018 / Accepted: 5 July 2018 / Published online: 3 August 2018 Handling editor: Brenda Koenig Co-Editors’ Note: This study was contributed in relation to the 20th International Conference on Aquatic Invasive Species held in Fort Lauderdale, Florida, USA, October 22–26, 2017 (http://www.icais.org/html/previous20.html). This conference has provided a venue for the exchange of information on various aspects of aquatic invasive species since its inception in 1990. The conference continues to provide an opportunity for dialog between academia, industry and environmental regulators. Abstract Rapid reaction to the initial discovery of invasive alien species (IAS) is key to eradication, but this is often frustrated by lack of resources and coordinated actions. However, examples of successful eradications may encourage and empower others to follow. Chub (Squalius cephalus) were illegally introduced into the River Inny in Ireland in the late 1990s or early 2000s, reputedly by anglers. The habitat in this river is favourable for chub and, should this species establish, it would likely compete with the indigenous fish communities and impact on other flora and fauna. Central Fisheries Board (now Inland Fisheries Ireland) coordinated chub removal operations and provided the necessary resources (manpower and equipment) to effectively remove chub from this large river. Three electric fishing crews supported by two tank boats and land-based personnel were required in each operation to effectively remove the chub. These crews worked on this task each year between 2006 and 2013. Between 2006 and 2008, 24 adult and two juvenile chub were removed and euthanised. In 2008, two chub were radio-tagged, released back to the river and tracked monthly for 12 months. Over the next two years these “Judas” chub, and two untagged male chub that were located in proximity to the tagged fish, were removed from the river. Intensive electric fishing of the river and regular contact with the local angling community between 2010 and 2017 revealed no further chub specimens. Monitoring of the fish populations in the river will continue but it is suspected that chub may have been eradicated from this river system and, hence, from the island of Ireland. This provides a rare case study of the potential to eradicate aquatic IAS when rapid reaction is resourced and coordinated. Key words: invasive species, freshwater fishes, rivers, competition, electric fishing Introduction (Butchart et al. 2010) and this has impacted native ecosystems (Nunes et al. 2015). The trend in IAS The introduction of species outside their natural range introductions in Ireland has increased dramatically is widely recognised as one of the main threats to since the beginning of the twentieth century and has biodiversity and the second leading cause of animal accelerated in the last two decades. This is particularly extinctions (MEA 2005). With increased globalisa- the case in inland waters, where the rate of increase tion, the number of invasive alien species (IAS) in among high-impact IAS has been greatest since the Europe has increased by 76% between 1970 and 2007 early 1980s (O’Flynn et al. 2014). 475 J. Caffrey et al. Eradication is the removal of every potentially (Esox lucius Linnaeus). Coarse angling is most popular reproducing individual of a species or the reduction on Ireland’s large river, canal and lake systems, of their population density below sustainable levels particularly in the midlands of the country. The (Myers et al. 2000). In Europe, relatively few eradica- species most sought after include roach (Rutilus rutilus tions have been successfully completed and most of Linnaeus), bream (Abramis brama Cuvier), roach × these have been on small islands or at a local scale. bream hybrids, rudd (Scardinius erythrophthalmus In addition, the majority of these eradications have Linnaeus), tench (Tinca tinca Linnaeus) and perch involved terrestrial vertebrates, with invertebrates, plants (Perca fluviatilis Linnaeus). While the market among or marine organisms (including fishes) rarely featuring domestic Irish anglers for coarse fishing is significant, (Genovesi 2005). However, once IAS have become that among visiting English anglers, and particularly established in an ecosystem, eradication may be an English competition anglers, is far greater. unachievable management option (Leuven et al. 2017). Currently, there are four freshwater fish species One reason why there are not more examples of that are considered invasive in Ireland and are on the successful eradications relates to the often limited list of non-native species that are subject to restric- ability to detect early invasions and to rapidly react tions under the EC (Birds and Natural Habitats) in a sufficiently robust manner when IAS incursions Regulations 2011 (Statutory Instrument 477/2011). are detected. It is clear that early detection coupled These are dace (Leuciscus leuciscus Linnaeus) and with appropriate rapid response will increase the roach, common carp (Cyprinus carpio Linnaeus) and likelihood of preventing the establishment and spread chub (Squalius cephalus Linnaeus). Dace and roach of recently introduced IAS. For early detection and have been in the country since they were introduced rapid response to be successful, three main compo- by English anglers in 1889 (Fitzmaurice 1984). The nents are required: (1) processes and plans to guide roach has spread widely in Irish watercourses in the detection and response actions, (2) tools with which recent decades and is now regarded as being natu- to respond, and (3) the capability and resources to ralised in the country (Caffrey et al. 2008). The spread see the response to a successful conclusion (Wotton of dace in Ireland, on the other hand, has been a more and Hewitt 2004). It is clear, also, that the response recent phenomenon and currently is directly impacting must be made sufficiently early in the invasion on native fishes in invaded rivers for food, habitat process to prevent the more widespread establish- and spawning substrates (Caffrey et al. 2007). The ment and impact of the target IAS. Being an island first reported introduction of common carp into the nation on the western edge of Europe, Ireland’s country was in 1626 (Grosart and Boyle 1886; freshwater fish community is less rich than that of Brazier et al. 2012). The fourth invasive species is Britain or mainland Europe (Moriarty and Fitzmaurice chub, which was only confirmed to be present in 2000). However, Ireland has an international reputation Ireland, in the River Inny, in 2005. Indications from as a destination for recreational anglers seeking wild angling reports were that small numbers of chub (no fish stocks in relatively unspoilt and unpolluted indication of numbers is available) had been illegally aquatic environments. Recreational angling and angling introduced by anglers on at least one occasion but tourism have been estimated to be worth €755 that their presence was still localised in this large million per annum, supporting 10,000 jobs, to Ireland river system. On confirming the presence of chub in in 2012 (Tourism Development International 2013). the river in autumn 2005, Central Fisheries Board Many non-native and potentially invasive fish (CFB) (which became Inland Fisheries Ireland (IFI) species have been deliberately stocked in the wild, in 2010) put forward a programme to rapidly aiming to promote the development of commercial respond to this deliberate introduction of a non- fisheries and recreational angling (Gherardi et al. native and potentially invasive fish species, and to 2009; Tricarico 2012). In fact, fishing/angling has make every effort to eradicate it from the river been identified as being among the most important before it spread to the wider network of connected pathways of initial introduction of invasive fishes in watercourses in Ireland. Europe (Gozlan et al. 2010; Nunes et al. 2015). Chub is indigenous to many parts of Europe, Further, the introduction of non-native fish species including England (Hellawell 1971). It is a slender- for recreational angling is recognised as a global bodied cyprinid that reaches an average fork length environmental problem and considered one of the (FL) of 30 to 45 cm and weight of 1.0 to 1.5 kg, principal causes of biodiversity loss in freshwater although fish to 80 cm (c. 7.5 kg) are known from ecosystems (Cambray 2003). The main angling cate- Europe. Chub typically have