Published on September 26, 2014
Invasive Species Management
Techniques in Ecology and Conservation Series Series Editor: William J. Sutherland Bird Ecology and Conservation: A Handbook of Techniques William J. Sutherland, Ian Newton, and Rhys E. Green Conservation Education and Outreach Techniques Susan K. Jacobson, Mallory D. McDuff, and Martha C. Monroe Forest Ecology and Conservation: A Handbook of Techniques Adrian C. Newton Habitat Management for Conservation: A Handbook of Techniques Malcolm Ausden Conservation and Sustainable Use: A Handbook of Techniques E.J. Milner-Gulland and J. Marcus Rowcliffe Invasive Species Management: A Handbook of Principles and Techniques Mick N. Clout and Peter A. Williams
Invasive Species Management A Handbook of Principles and Techniques Edited by Mick N. Clout and Peter A. Williams 1
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Introduction Invasive alien species are now one of the main threats to biodiversity worldwide. The transport of organisms by humans since earliest times, and now through increased levels of trade and tourism, has led to the widespread breaching of nat-ural biogeographic barriers at historically unprecedented rates. The consequences for native biota and natural ecosystem processes can be severe, especially in previ-ously isolated ecosystems. Global climate change further exacerbates the spread of alien species, as climatic zones shift and potential ranges expand. Th is book focuses on those alien species, spread inadvertently or deliberately by humans, which invade natural or semi-natural ecosystems. Such species are agents of ecological change, which includes extinction or decline of vulnerable endemic species, alteration of the structure and composition of communities, loss of ecosys-tem services, and disruption of successional pathways. Alien species causing eco-logical change can be termed ‘invasive alien species’, or merely ‘invasive species’. Th ese invaders are also given many other names, including pests, weeds, exotics, aliens, introduced species, or non-indigenous species. Biological invasion is a staged process whereby, to become a successful invader, a species must cross a series of spatial, environmental, and biological barriers. Th e main stages are transport, establishment, and spread. Diff erent sets of spe-cies attributes are likely to confer potential success at these diff erent stages, (e.g. attributes necessary for transoceanic dispersal may be quite diff erent from those favouring population establishment at a new location). Managing biological inva-sions therefore involves identifying pathways or vectors and the species attributes that confer success at each barrier, and using appropriate methods or strategies to prevent, eradicate, or control the species of concern. To say that alien invasions are a human construct is both a tautology and a fact. But because we are the principal cause of invasions, we are also, paradoxically, the principal source of the solution (McNeely 2006). Th e purpose of this book is to introduce the reader to the underlying principles necessary for the successful pre-vention and control of biological invasions. Although concerned primarily with conserving biodiversity, many of the principles are applicable to a broader range of sectors. Th is applies particularly to the fi rst eight chapters. Invasions occur across the full spectrum of taxonomic groups, as shown in Chapters 9–14, and they often interact, so that managing the system as a whole becomes necessary (Chapter 15). Th e role of humans in the spread of invasive species probably began with the introduction of dogs and edible plants by hunter-gatherers, before the advent of agriculture. Many prehistoric invasions are so ancient, such as the introduction of dogs (dingoes) to Australia and the Polynesian rat throughout the Pacifi c, that the main evidence we have of their initial impacts are the bones of extinct species.
vi | Introduction Arguably the most culturally infl uential biological invasion was the spread by Roman trade of the black rat through Europe. Th ese animals became the carri-ers of the bubonic plague that decimated the European population in the years immediately following 1348. Th is led to such restructuring of western society that it laid the foundations for the Renaissance (Benedictow 2004). Th is in turn, led to the intensive study of nature and so, it could be argued, to the concept of nature conservation itself, and ultimately to the concept of alien species and their impacts on nature. Th e modern era of alien species dispersal and introductions began only c. 500 years ago with the advent of square-rigged ships in the 15th century and the discov-ery of the New World. Now we live in a world where anything can be transported anywhere, often overnight, providing a myriad of vectors and pathways, some purposeful and others not, for everything from microbes or mussels, to mice and mambas. As a consequence, the degree of international trade into a country is now the strongest predictor of the number of invasive alien species in that country (Westphal et al. 2008). Th e dependence of human societies worldwide on intro-duced crops and livestock has led to many introductions, and trade has fuelled other global changes, including human population growth. Biological invasions have had impacts on many aspects of human society, includ-ing agriculture, horticulture, aquaculture, and human health (Pimental 2002). Th ey also have had major impacts on biological diversity and ecosystem services. Examples of invasive alien species with severe impacts range across the whole globe. Avian malaria, which is carried by alien mosquitoes, has virtually eliminated native birds below 1300m in Hawaii. Accidental introductions of predatory vertebrates, such as rats or the brown tree snake, have decimated vulnerable native wildlife in many parts of the world, especially in previously isolated island ecosystems. Introductions of plants for pleasure or profi t, including via well-intentioned aid projects, have seen whole ecosystems transformed, e.g. through the spread of aca-cia in South Africa. Invasions in fresh and salt water, of both plants and animals, have been equally devastating. Examples include the reduction of aquatic biodiver-sity and devastation of local economies by water hyacinth covering tropical lakes. Many similar examples, and the pathways through which they have occurred, are summarized by Wittenberg and Cock (2001); and a sound classifi cation scheme is suggested by Hulme et al. (2008). As human society has tried to adapt to biological and environmental changes, even potential solutions have sometimes led to yet more devastating invasions. An example is the historical liberation of mustelids in New Zealand as biological con-trol agents for previously introduced rabbits—leading to decline of native wildlife species, but no eff ective control of rabbits. Th e concurrent increase in global consumption of resources, especially fossil fuels, has lead to human-induced climate change, which is already aff ecting the range and behaviour of invasive species. A current fear, generated by diminishing resources and the ‘fuel crisis’, is that one proposed solution, in the form of crops grown for biofuel, will spawn yet more weed invasions. Th e pressure on biological systems is
Introduction | vii relentless. Although public awareness and research into biological invasions has increased dramatically since the book by Elton (1958), there has not been a propor-tional investment in the management of invasive alien species (Hulme 2006). Th ose working with alien species on a daily basis must nevertheless continually be aware we do not all have the same value systems and consequently not everyone accepts such species as necessarily undesirable. Some claim that the drive to reduce the spread and impacts of alien species is displaced xenophobia and is lineally descended from the native plant-loving Nazis (see Simberloff 2003a). Although this argument has been deconstructed by Coates (2006), we confess to some dis-quiet over the frequent use of martial metaphors by invasion biologists to describe alien (or non-native) species. Nevertheless, we are aware that there is no universally accepted set of terms to describe an alien species, as it progresses from a benign spe-cies, to a potential threat, to becoming invasive and almost universally unwanted in a new area. For this reason, we have not attempted to standardize terms amongst the contributors to this volume. Although biological invasions are not everyone’s primary concern in life, and care must be taken in the terms we use to communicate about them, there is now tremendous popular support in many places for their eff ective management. Obtaining this support, and directing it appropriately, is a crucial step in con-trolling invasions. Th is can be achieved, as Boudjelas explains (Chapter 7), only by harnessing the values that people already have towards natural systems, and showing how invasive species interfere with these. As explained by De Poorter (Chapter 8), at the international level there are now several laws and conventions that provide support for the management of alien species and oblige governments to prevent their introduction and spread and minimize their impacts. Some of the strongest international legislation aims to prevent the introduc-tion of alien species from one country to another, and began to be enacted over 100 years ago (Maynard and Nowell, Chapter 1). Th ese authors go on to explain the multitude of pathways by which alien species may enter new areas and the monitoring systems and procedures that must be put in place to prevent introduc-tion. Th ey also explain that predicting which species and pathways are likely to be problematic is important for designing quarantine systems, and even for locating facilities. Stohlgren and Jarnevich (Chapter 2) explain what we need to know to estimate, and predict the risks associated with invasive organisms—there are net bioeconomic benefi ts to doing this (Keller et al. 2007) In the end, some alien species are always going to slip through the border, perhaps because neither the organism nor its pathway was identifi ed as a threat. At this point, future invasions can be prevented only if eff ective detection and early warning systems are in place and are backed up by ready action plans as described by Holcombe and Stohlgren (Chapter 3). Th ese authors point out that the window of opportunity here may be quite narrow before the species becomes fully natu-ralized, (i.e. maintaining a self-sustaining population in the wild). Once this hap-pens, the problems change to considering whether or not it is possible to eradicate such populations. Th ere are signifi cant economic and environmental benefi ts of
viii | Introduction eradication, as opposed to perpetual control. However, unless they are properly planned and executed, eradication programmes often fail, for reasons detailed by Parkes and Panetta (Chapter 4). Key factors in eradication success are proper plan-ning, commitment to persevere until the last individual is removed, and ensuring that reinvasion is prevented. If eradication is not possible, the issue then becomes one of containment, to prevent the invasive species expanding to saturate all poten-tial habitats as diff erentiated by Grice (Chapter 5). Containment is a valid strat-egy only for those situations where it is possible to curb or halt the rate of range expansion. In reality, there is seldom a ‘permanent’ barrier to range expansion (Grice, Chapter 5) and the vast majority of resources, are expended on controlling the populations to minimize their impacts in particular places. Biological control usually has this eff ect because one organism is seldom able to exterminate another, as Murphy and Evans explain (Chapter 6). ‘Classical’ biological control has mostly been for the control of arthropod and plant invaders, but eff orts have been made on invasive mammals, invasive marine organisms, and other species. Th e principles outlined in Chapters 1–8 are applicable to most invasive species in a range of habitats. However, since there are particular management challenges associated with diff erent groups of invasive organisms, the second part of the book (Chapters 9–15) consists of individual chapters devoted specifi cally to these. Firstly, in a chapter on terrestrial plants, Holt (Chapter 9) explains how their par-ticular characteristics, such as high genetic plasticity and the tremendous dispersal potential of propagules that can ‘hide’ in seed banks, raise particular problems at all stages of invasion. Aquatic plants have many similar characteristics, but, as described by Coetzee and Hill (Chapter 10), they also have some vitally diff erent ones relevant to their management—such as reduced accessibility to the foliage for entirely submerged species. However, in the case of still waters, the distribu-tion of aquatic invaders is often confi ned to discrete areas, with the result that infestations of aquatic plants have frequently been eradicated. Techniques ran-ging from biocontrol to total modifi cation of the environment (e.g. drainage) have been employed to eradicate aquatic invasive plants. Invertebrates are arguably the most pervasive and widespread group of invaders around the planet, transported (usually inadvertently) by a variety of vectors and pathways. Th e management of invasive invertebrates presents special challenges, as described by Green and O’Dowd (Chapter 11) in their illuminating case study of the yellow crazy ant on Christmas Island. Prevention or early detection and eradication are the best pol-icies for invertebrate invaders, as they are for other organisms. Th ese strategies are likely to be successful on a landscape scale only when the biology of the species is properly understood and the necessary resources are committed for the duration of the programme. Terrestrial vertebrate pests are arguably the best-studied and theoretically the most tractable group of invaders, since they do not have dormant life stages and, with the notable exception of commensal rodents, are rarely transported by accident. However, there are some special challenges in managing terrestrial vertebrates, as described by Parkes and Nugent (Chapter 12). Terrestrial vertebrates have been
Introduction | ix introduced to many locations as domestic livestock, as pets, or for hunting, and are often valued by people. Opposition by some sectors of the community to their eradication or control is therefore more common than for most other groups of organisms. Other challenges in the management of terrestrial vertebrate pests stem from their relatively complex behaviour. In aquatic ecosystems, fi sh are the major group of vertebrate invaders. Many fi sh species have been deliberately transported around the world for sport, aqua-culture, or as aquarium pets. Like other groups of organisms, some are relatively benign, whereas others are highly invasive. Ling (Chapter 13) describes methods and approaches that have been successfully used to prevent, control, or eradicate invasive fi sh from a range of aquatic habitats around the world, and some of the special diffi culties that are inherent in their management. Th e management of invasive species in marine environments poses challenges that are not prevalent in freshwater and terrestrial systems. As pointed out by Piola and colleagues (Chapter 14), marine environments are expansive, inter-connected, and often only partially accessible. Although the successful management of marine invaders must clearly focus on eff ective prevention, there are nevertheless some tools available for post-border management of marine pest species. Eff ective marine biosecurity should consist of vector management, surveillance, incursion response, and control measures that target particular pests or suites of functionally similar ones, coupled with generic approaches to reduce human-mediated transport. Finally, it is increasingly evident that managers must be concerned not only with the eff ects of invasive species on native species in the ecosystems that they have invaded, but also with the interactions between invasive species. Bull and Courchamp (Chapter 15) use examples of eradications of invasive vertebrates from islands to illustrate this; highlighting phenomena such as hyper-predation, mesopredator release, competitor release, and the release of invasive plants from introduced herbivores. Understanding the functional relationships within invaded ecosystems is a signifi cant challenge, but is important for the restoration of native species and natural ecosystem processes. Th is underscores the point that the eff ective management of invasive species requires underpinning by sound ecological science. Th e subject of invasive species management is so extensive that a single book cannot possibly prescribe detailed techniques for every species or situation. Th e fi rst aim of this book is therefore to describe strategies for managing invasive spe-cies at diff erent stages of the invasion process. Th e second aim is to describe the general tools and approaches that are recommended for the successful manage-ment of particular groups of invasive organisms. We hope that this handbook will be useful to a range of readers, including invasive species managers, legislators, students, and the broader community concerned with biological conservation. Mick N. Clout and Peter A. Williams
x | Introduction Acknowledgements We thank all of the contributers to this book, the staff of OUP for their profes-sional help, and Carola Warner for her invaluable assistance in the completion of this work.
Contents Contributors xxi 1 Biosecurity and quarantine for preventing invasive species 1 Glynn Maynard and David Nowell 1.1 Introduction 1 1.2 Invasiveness and impacts 1 1.3 Legislative frameworks 3 1.3.1 International framework 3 1.3.2 National frameworks 3 1.4 Pathways 4 1.4.1 Natural spread and host range extension 5 22.214.171.124 Natural disasters 5 1.4.2 Accidental introductions 5 126.96.36.199 Trade 5 188.8.131.52 Traditional movement of people and goods 6 184.108.40.206 Emergency food, disaster relief, and development aid 6 1.4.3 Deliberate introductions 7 220.127.116.11 Biological control 7 18.104.22.168 Plant introductions 8 22.214.171.124 Smuggling 9 1.5 Actions 9 1.5.1 Pre-entry 10 1.5.2 Entry (border) 11 1.5.3 Emergency actions 14 1.6 Summary 16 1.7 Acknowledgements 18 2 Risk assessment of invasive species 19 Thomas J. Stohlgren and Catherine S. Jarnevich 2.1 Introduction 19 2.1.1 Why do we need a formal approach to invasive species risk assessment? 20 2.1.2 Current state of risk assessment for biological invaders 21 2.1.3 The ultimate risk assessment challenge 22
xii | Contents 2.2 Components of risk assessment for invasive species 23 2.2.1 Information on species traits 23 2.2.2 Matching species traits to suitable habitats 25 2.2.3 Estimating exposure 27 2.2.4 Surveys of current distribution and abundance 29 2.2.5 Understanding of data completeness 30 2.2.6 Estimates of the ‘potential’ distribution and abundance 31 2.2.7 Estimates of the potential rate of spread 31 2.2.8 Probable risks, impacts, and costs 32 2.2.9 Containment potential, costs, and opportunity costs 33 2.2.10 Legal mandates and social considerations 33 2.3 Information science and technology 34 2.4 The challenge: to select priority species and priority sites 34 2.5 Acknowledgements 35 3 Detection and early warning of invasive species 36 Tracy Holcombe and Thomas J. Stohlgren 3.1 Introduction 36 3.1.1 Fire as a metaphor for invasion 37 3.1.2 Defi nitions 37 3.2 Early detection and rapid assessment 38 3.3 Guiding principles for early detection and rapid assessment 40 3.3.1 Data and information management 41 3.3.2 Global and regional invasive species databases 41 3.3.3 Species reporting requirements 45 3.4 Conclusions 45 4 Eradication of invasive species: progress and emerging issues in the 21st century 47 John P. Parkes and F. Dane Panetta 4.1 Introduction 47 4.2 From scepticism to positive consideration 47 4.3 Feasibility 48 4.4 Advances in eradication of vertebrate pests 50 4.5 Advances in eradication of weeds 52 4.6 Emerging issues 55 4.6.1 Eradication on mainlands 55 4.6.2 Does scale count? 56 4.6.3 Delimiting boundaries and detecting survivors and immigrants 56 4.6.4 A particular problem with weeds—seed banks 57
Contents | xiii 4.6.5 Tricky species 58 4.6.6 Institutional commitment 58 4.6.7 Local elimination 59 4.7 Conclusions 59 4.8 Acknowledgements 60 5 Principles of containment and control of invasive species 61 Tony Grice 5.1 Introduction 61 5.2 Control and containment—strategies without an end-point 62 5.2.1 When to contain, when to control 63 5.2.2 Feasibility of containment 63 5.2.3 Elements of a containment strategy 65 5.2.4 To control or not to control 65 5.3 Principles of containment and control 67 5.3.1 Evaluate impacts of invasive species 67 5.3.2 Assemble knowledge of species’ biology, ecology, and responses to management 67 5.3.3 Map distribution and abundance 68 5.3.4 Set priorities for species and places 68 5.3.5 Coordinate management of multiple, functionally similar invasive species 69 5.3.6 Take action early in the invasion process 69 5.3.7 Direct effort where benefi t: cost ratio is high 70 5.3.8 Direct containment effort at the periphery of an expanding distribution 70 5.3.9 Exploit natural barriers to range expansion 70 5.3.10 Exploit times when invasive species’ populations are low 71 5.3.11 Acquire continuing commitment 71 5.3.12 Resolve confl icting interests 72 5.3.13 Monitor the consequences 72 5.4 Examples 73 5.4.1 Containment of rubber vine in northern Australia 73 5.4.2 Containment of leucaena—a commercially grown fodder shrub in Australia 74 5.4.3 Control of invasive mammalian predators in New Zealand 74 5.4.4 Invasive pasture grasses in Australia 75 5.5 Conclusions 76 5.6 Acknowledgements 76
xiv | Contents 6 Biological control of invasive species 77 Sean T. Murphy and Harry C. Evans 6.1 Introduction 77 6.2 Why classical biological control is an appropriate tool for managing invasive species 78 6.3 The practice of classical biological control 79 6.3.1 Early history and development 79 6.3.2 Biological control projects against invasive species in natural ecosystems 80 6.3.3 Success, failures, and the economics of biological control 83 6.4 Modern methods of biological control 86 6.4.1 The characteristics of effi cacious agents 86 6.4.2 Issues related to ecological risks 87 6.5 Constraints to the implementation of biological control 91 6.6 Conclusions 92 7 Public participation in invasive species management 93 Souad Boudjelas 7.1 Introduction 93 7.2 Why involve the public? 93 7.2.1 Ethics 93 7.2.2 Compliance 93 7.2.3 Effectiveness 95 126.96.36.199 Locally relevant 95 188.8.131.52 Maximize the resource effort 95 184.108.40.206 Public support 98 220.127.116.11 Part of the problem; part of the solution 99 7.3 How to successfully involve the public 99 7.4 Conclusions 106 8 International legal instruments and frameworks for invasive species 108 Maj De Poorter 8.1 Introduction 108 8.2 Scope and types of international instruments 110 8.3 Invasive species and global instruments for conservation of biological diversity 112 8.3.1 The Convention on Biological Diversity (CBD) 112 8.3.2 The Convention on Wetlands (Ramsar) 113 8.3.3 The Convention on International Trade in Endangered Species (CITES) 114 8.3.4 Convention on the Conservation of Migratory Species of Wild Animals (CMS) 114
Contents | xv 8.3.5 The UN Convention on the Law of the Sea (UNCLOS) 115 8.3.6 The Code of Conduct for Responsible Fisheries 115 8.4 Invasive species and regional instruments for conservation of biological diversity 115 8.4.1 The International Council for the Exploration of the Sea (ICES) Code of Practice 115 8.4.2 United Nations Environment Programme (UNEP) Regional Seas Programme 116 8.4.3 Other agreements 116 8.5 Invasive species and instruments relating to phytosanitary and sanitary measures 117 8.5.1 The International Plant Protection Convention (IPPC) 117 8.5.2 Other regulations 117 8.6 Invasive species and instruments relating to transport operations 118 8.6.1 International Maritime Organization (IMO) 118 8.6.2 The International Civil Aviation Organization (ICAO) 119 8.7 Relationship with multilateral trading systems 119 8.8 International instruments and approaches relevant to invasive species 120 8.9 Relation between invasive species and sustainable development programmes 121 8.10 Regional strategies and plans 122 8.10.1 South Pacifi c Regional Environment Programme (SPREP): invasive species strategy for the Pacifi c Island region 122 8.10.2 European Strategy (Council of Europe) 122 8.10.3 European Union 122 8.10.4 Pacifi c Invasives Initiative 122 8.10.5 Pacifi c Ant Prevention Programme (PAPP) 123 8.11 International programmes and organizations 123 8.11.1 The Global Invasive Species Programme (GISP) 123 8.11.2 The International Union for Conservation of Nature and Natural Resources (IUCN) 124 8.11.3 The Invasive Species Specialist Group (ISSG) 124 8.11.4 The Global Invasive Species Database (GISD) and Global Invasive Species Information Network (GISIN) 124 8.12 Conclusions 125 9 Management of invasive terrestrial plants 126 Jodie S. Holt 9.1 Introduction 126 9.2 Classifi cation of weeds and invasive plants 126 9.3 Plant characteristics important in management 127
xvi | Contents 9.4 Management of terrestrial invasive plants 128 9.4.1 Principles of prevention, eradication, containment, and control 128 9.4.2 Physical methods of invasive plant control 132 18.104.22.168 Hand pulling and using manual implements 132 22.214.171.124 Fire 133 126.96.36.199 Using machines for invasive plant control 134 188.8.131.52 Mulching and solarization 136 9.4.3 Cultural methods of invasive plant control 136 184.108.40.206 Prevention 136 220.127.116.11 Competition 137 9.4.4 Biological control 138 9.4.5 Chemical control 138 9.4.6 Integrated weed management 139 10 Management of invasive aquatic plants 141 Julie A. Coetzee and Martin P. Hill 10.1 Introduction 141 10.2 Plant characteristics important in management 141 10.3 Modes of introduction and spread 145 10.4 Management of aquatic invasive plants 146 10.4.1 Utilization 146 10.4.2 Manual/mechanical control 146 10.4.3 Herbicidal control 148 10.4.4 Biological control 148 10.4.5 Integrated control 151 10.5 Prevention, early detection, and rapid response 152 11 Management of invasive invertebrates: lessons from the management of an invasive alien ant 153 Peter T. Green and Dennis J. O’Dowd 11.1 Introduction 153 11.2 History 155 11.2.1 The yellow crazy ant as a pantropical invader 155 11.3 YCA invasion of Christmas Island 156 11.3.1 The interim response 157 11.3.2 The aerial control campaign 161 18.104.22.168 Legislative approval 162 22.214.171.124 The helicopter 162 126.96.36.199 Dispersion of Presto®01 ant bait 163 188.8.131.52 Mapping supercolonies 163 184.108.40.206 Trial of aerial baiting 164
Contents | xvii 220.127.116.11 Measuring the success of the island-wide operation 164 18.104.22.168 Non-target impacts 165 11.3.3 Evaluation and lessons learned from the aerial campaign 167 11.4 Conclusions 170 11.5 Acknowledgements 171 12 Management of terrestrial vertebrate pests 173 John P. Parkes and Graham Nugent 12.1 Introduction 173 12.2 Tools to prevent new species arriving 174 12.3 Tools to manage established wild populations 175 12.3.1 Detection tools 175 12.3.2 Exclusion 176 12.3.3 Control tools 176 22.214.171.124 Snares and traps 176 126.96.36.199 Shooting 178 188.8.131.52 Poisoning 179 184.108.40.206 Biocontrol 181 220.127.116.11 Fertility control 182 12.4 Conclusions 183 13 Management of invasive fi sh 185 Nicholas Ling 13.1 Introduction 185 13.2 The role of humans 186 13.3 Risk assessment 187 13.4 Economics of eradication and control 188 13.5 Marine versus freshwater 188 13.6 Indigenous fi sh as invasive species 188 13.7 Routes of introduction and spread 189 13.7.1 Ballast water and vessel hull transport 189 13.7.2 Live fi sh importation and sale 189 13.7.3 Aquaculture for the aquarium trade 191 13.7.4 Aquaculture for food 191 13.8 Eradication and control 192 13.8.1 Early response 192 13.8.2 Response tools 192 18.104.22.168 Preventing spread: physical barriers, electrical barriers, interstate/interisland biosecurity barriers 192 22.214.171.124 Chemical control 193 Rotenone 195 Antimycin-A (Fintrol®) 196
xviii | Contents Natural saponins 196 TFM and niclosamide 197 126.96.36.199 Biocontrol measures 197 Predatory fi sh 197 Pheromones 197 Fish pathogens 197 Habitat modifi cation and restoration 198 Immunocontraceptive control and genetic modifi cation 198 188.8.131.52 Physical removal 199 13.8.3 Case studies in the effectiveness of physical removal 200 184.108.40.206 Nile perch in Lake Victoria 201 220.127.116.11 Common carp in Lakes Crescent and Sorrell, Tasmania 203 13.9 Conclusions 203 14 Marine biosecurity: management options and response tools 205 Richard F. Piola, Chris M. Denny, Barrie M. Forrest, and Michael D. Taylor 14.1 Introduction 205 14.2 Pre-border management 207 14.2.1 Human-mediated invasion pathways 207 14.2.2 Management of human-mediated pathways 210 14.3 Post-border management 211 14.3.1 Early detection and rapid response 212 14.3.2 Response tools 214 18.104.22.168 Physical removal 214 22.214.171.124 Wrapping and smothering 221 126.96.36.199 Physical treatment 224 188.8.131.52 Chemicals 224 14.4 Discussion 227 14.5 Acknowledgments 231 15 Management of interacting invasives: ecosystem approaches 232 Leigh S. Bull and Franck Courchamp 15.1 Introduction 232 15.2 Cases when removal of alien species does not lead to ecosystem recovery 234 15.2.1 When the alien species has an important functional role 234
Contents | xix 15.2.2 When the alien species has a long lasting effect 234 15.2.3 When the alien species interacts with other aliens 235 184.108.40.206 Interactions resulting from conspicuous aliens Hyperpredation 235 220.127.116.11. Interactions resulting from inconspicuous aliens Release from introduced herbivores 238 The mesopredator release effect 241 The competitor release effect 242 15.3 Mitigating actions 243 15.3.1 Pre-eradication studies 244 15.3.2 Exclosure experiments 244 15.3.3 Control strategies 245 18.104.22.168 Hyperpredation 245 22.214.171.124 Mesopredator release 245 126.96.36.199 Competitor release 245 188.8.131.52 Post-eradication monitoring 246 15.4 Conclusions 247 References 249 Index 295
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Contributors Souad Boudjelas Pacifi c Invasives Initiative School of Biological Sciences The University of Auckland Auckland, New Zealand Leigh S. Bull Universite Paris-Sud XI Laboratoire Ecologie, Systématique et Evolution Orsay, France Mick N. Clout Centre for Biodiversity and Biosecurity School of Biological Sciences The University of Auckland Auckland, New Zealand Julie A. Coetzee Rhodes University Department of Zoology and Entomology Grahamstown, South Africa Franck Courchamp Universite Paris-Sud XI Laboratoire Ecologie, Systématique et Evolution Orsay, France Maj De Poorter Invasive Species Specialist Group Centre for Biodiversity and Biosecurity The University of Auckland Auckland, New Zealand Chris M. Denny Cawthron Institute Nelson, New Zealand Harry C. Evans CAB International Europe (UK) Silwood Park Ascot, UK Barrie M. Forrest Cawthron Institute Nelson, New Zealand Peter T. Green La Trobe University Department of Botany Bundoora, Australia Tony Grice CSIRO Sustainable Ecosystems Aitkenvale, Australia Martin P. Hill Rhodes University Department of Zoology and Entomology Grahamstown, South Africa Tracey Holcombe US Geological Survey National Institute of Invasive Species Science Fort Collins Science Centre Fort Collins, CO, USA Jodie S. Holt University of California Riverside, CA, USA Catherine S. Jarnevich US Geological Survey National Inst of Invasive Species Science Fort Collins Science Centre Fort Collins, CO, USA Nicholas Ling The University of Waikato Hamilton, New Zealand Glynn Maynard Offi ce of the Chief Plant Protection Offi cer, Department of Agriculture, Fisheries & Forestry Canberra, Australia
xxii | Contributors Sean T. Murphy CAB International Europe (UK) Silwood Park Ascot, UK David Nowell International Plant Protection Convention (IPPC) Rome, Italy Graham Nugent Landcare Research NZ Limited Lincoln, New Zealand Dennis O’Dowd Australian Centre for Biodiversity School of Biological Sciences Monash University Victoria, Australia F. Dane Panetta Department of Natural Resources and Mines & CRC for Australian Weed Management Alan Fletcher Research Station Sherwood, Australia John P. Parkes Landcare Research NZ Limited Lincoln, New Zealand Richard F. Piola Cawthron Institute Nelson, New Zealand Thomas J. Stohlgren US Geological Survey National Institute of Invasive Species Science Fort Collins Science Centre Fort Collins, CO, USA Michael D. Taylor Cawthron Institute Nelson, New Zealand Peter A. Williams Landcare Research NZ Limited Nelson, New Zealand
1 Biosecurity and quarantine for preventing invasive species Glynn Maynard and David Nowell 1.1 Introduction The saying ‘prevention is better than cure’ applies to the entry of invasive species but this is diffi cult to achieve, particularly in the absence of physical or ecological barriers to the movement of invasive species, or where human activities and vec-tors provide pathways for their entry. For the purposes of this chapter, the term ‘invasive species’ applies to those that enter and establish in a new area and have the ability to spread aggressively, to intrude or overwhelm other organisms. This can apply to organisms affecting human food safety, human health and culture, and agricultural, natural terrestrial, and aquatic ecosystems. Biosecurity includes all policies and measures that a country implements to minimize these harmful affects, ranging from preventing the entry of unwanted species into an area to their management if they do enter. Biosecurity is a broader concept than quarantine (system), but at times these terms are used interchangeably. Together they are usu-ally integrated measures that cross over all sectors that relate to the protection of the environment in general. Internationally the term quarantine is used in several ways. In the broad sense it refers to all activities aimed at preventing the introduction, and/or spread, of a species of concern. In a narrower sense, it is the offi cial confi nement of organisms that have a risk of invasiveness (FAO 2007a). In this chapter, the broader sense of quarantine refers to a quarantine system and the narrower sense refers to a quaran-tine facility, quarantine procedure, or quarantine measure. All of these systems or measures are tools used to reduce the likelihood of entry of invasive organisms. We stress that accurate identifi cation of the species involved is critical to all aspects of biosecurity and invasive species management to enable appropriate deci-sions or actions. 1.2 Invasiveness and impacts The impacts of invasive species range from negligible to extremely high and they can be diffi cult to understand. Certain components are clearly quantifi able, such
2 | Invasive species management as the loss of human lives (e.g. West Nile disease) and fi nancial losses (e.g. direct loss of agricultural production or increased cost of control measures). Many other impacts are less easily quantifi ed, including environmental impacts (e.g. loss or change of biodiversity), impingements on human lifestyle, and amenity losses. In general, if invasive species can be prevented from establishing in an area, the resources used in prevention are usually signifi cantly lower than those needed for eradication, containment, long-term control, or the consequences of doing noth-ing. Hence, where an invasive species does enter and is detected, it is essential to have well organized and implemented emergency management procedures to minimize the risk of widespread establishment and the subsequent need for an eradication campaign. Eradication can be diffi cult to achieve and often entails fairly severe measures that may need to be maintained over lengthy periods (see Chapter 4). Many organisms that enter a new or endangered area either do not establish or necessarily become pests even if they do establish. Other species will establish but do not appear to have a signifi cant impact, at least initially, because the popula-tions are small in size and initially not problematic. However, some species, after several to many generations—which may take months to years—the population can reach suffi ciently high levels to become problematic. Invasiveness may increase with a change in conditions, ranging from broad-scale climate change resulting in more available habitat, to a single event such as the introduction of a more effi cient plant pollinator resulting in greater seed set. Such changes may result in previously benign species becoming invasive with unacceptable impacts. In addition to exotic species, previously benign native species can invade, through habitat modifi cation such as the introduction of new nutrient resources (e.g. new hosts), to such an extent that they require control. A critical aspect of all aspects of biosecurity, particularly at the border, is the great diffi culty of predicting which species will be invasive. Th ere is no single set of characteristics that determine if a species will be invasive, although certain char-acteristics increase the likelihood that a species is more likely to be successful in establishing and possibly becoming invasive. A general formula for invasiveness = [Nutrition availability (food or niche availability) + capacity to spread + sen-sitivity (ecological and human) of ecosystem to change/impact] × Constraints (climate requirements, parasites, disease, reproductive constraints etc.) Th ere are many texts on this subject with greater or lesser details with many predictive models available that have varying degrees of usefulness. Th e major requirement for a species to establish and invade in an area is the availability of suit-able nutrition, which ranges from host organisms (e.g. parasites) to niches on the landscapes. Once established, other constraints that determine the extent of impact include: its dispersal capacity either by its own means such as fl ight, or mediated by other means such as passive wind dispersal or attachment to bird feathers or mammal coats; tolerance of diff erent environments; lack of competition at the site of invasion; presence/absence of predators, disease, or parasites; abundance of high value nutrition; host suitability; reproductive capacity; climate; coincidence of
Biosecurity and quarantine for preventing invasive species | 3 climate and host life stages; niches availability and disturbance levels (e.g. change of landscape by humans). 1.3 Legislative frameworks 1.3.1 International framework When considering the establishment of quarantine systems/measures there are many issues to be taken into account. At the broadest level there are obligations to international conventions and intergovernmental organizations to which govern-ments are members or contracting parties. The principle conventions and inter-governmental organizations that deal with invasive species are the International Plant Protection Convention (IPPC), World Organisation for Animal Health (OIE), Convention on Biological Diversity (CBD), Codex Alimentarius, Ballast Water (International Maritime Organisation, IMO), and the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). These international agreements provide a framework of principles to guide a coun-try in developing mechanisms/measures to reduce the threats from invasive species (see Chapter 8). Th e agriculture sector has been developing procedures, methodologies, and tools to lower the likelihood of entry of organisms of concern for many years. Th e fi rst international plant health agreement was signed in Bern, Switzerland in 1881, as a response to spread of a plant pest, Phylloxera, on grape vine planting material. It was called the Convention on measures to be taken against Phylloxera vastatrix (now renamed Daktulosphaira vitifoliae). Th is agreement was the forerun-ner of the current IPPC. Over the past 12 years international phytosanitary stand-ards (ISPMs) have been developed within the framework of the IPPC, to provide guidance on a range of plant quarantine issues covering plant pests—under IPPC defi nitions the term plant pest includes plant pathogens, insect pests, and weeds (FAO 1997, 2004a–c, 2005a, 2007a,b; IPPC 1997) Th ese standards are generally adaptable across all sectors. Th e risk assessment standards have been unoffi cially adapted for use by some scientists for invasive species in areas other than agricul-ture, e.g. aquatic species. 1.3.2 National frameworks These agreements, international standards, and frameworks are often adminis-tered through different national mechanisms, usually implemented by different sectors of government, and hence not necessarily applied in a unifi ed or coordi-nated manner. National issues that can impact on a country’s capacity to implement quarantine systems/measures include the national economic status, eff ectiveness of govern-ance, social and political stability, and the well-being of a populace. If major social problems prevail—such as poverty, famine, civil unrest, or war—then the preven-tion of entry or deliberate introduction of potential invasive species is likely to have
4 | Invasive species management a relatively low national priority. Th at is, the short-term imperatives of human issues are likely to have higher priority than establishing quarantine measures despite the potential longer-term consequences of not doing so. 1.4 Pathways Apart from the biological characteristics of invasive organisms, many other factors need to be considered during the implementation of quarantine measures. In par-ticular are the pathways via which organisms can enter new areas. There are three broad categories of pathways of introduction: 1) Species that spread naturally either passively by water or wind, including extreme events such as cyclones, or actively fl ying, crawling, or swimming. 2) Species that are accidentally introduced hitch-hiking or vectored on/by something for example,: during trade; movement of material during emer-gency relief or confl icts; traditional movement of people; movement of plants, animals, or soil; scientifi c materials; traveller’s personal effects; move-ment of contaminated agricultural, military, or industrial equipment; ships, including ballast water. 3) Species that are deliberately introduced, e.g. new genetic stock, biological control, hunting, pets, or ornamental trade. These may be introduced legally or illegally (smuggled) into an area. A further layer of complexity arises when one community considers an organism invasive and another community (often in the same country) considers the species benefi cial. Th e volume of human-facilitated movement of goods and organisms, and people travelling around the globe is huge and increasing every year. Th ese move-ments provide pathways that are possibly the most signifi cant sources of poten-tial invasive organisms. Every traveller and item of goods that are imported into a country potentially provides a pathway for an invasive species. Th e following describes some data of known movements of people and goods in two countries with relatively well-controlled borders, the USA and Australia. Th ey give some idea of the magnitude of the task of minimizing the risk of invasive species entering a country. Both the USA and Australia have invested heavily in the prevention of entry of invasive organisms, as well as in management of pest incursions. Th e USA has a mix of long land borders and sea borders. Australia is entirely surrounded by sea with only one area in close proximity to another country. Th e USA intercepted about 325,000 pests between 1991–96, and inspected over 315,000 ships. In 1996, they inspected over 66 million passengers (APHIS web facts). Australia intercepted about 140,000 pests between 1993–2003. In the year 2006–07 there were 1.6 million sea cargo containers inspected; rising to 1.8 million in 2007–08—an increase of over 10% in one year. Currently12 million air passengers are screened each year and around 45,000 items of quarantine con-cern are seized every month and about a quarter of these are undeclared—there
Biosecurity and quarantine for preventing invasive species | 5 are 3,300 staff (inspection and non-inspection) in the agency that manages the international border. Hence, to complement the eff ectiveness of the work done by government agencies, there needs to be a high level of cooperation by a greater part of the populace 1.4.1 Natural spread and host range extension The Queensland fruit fl y (Bactrocera tryoni) exemplifi es the combination of nat-ural spread and host range extension resulting from human modifi cation of the environment. It is native to south east Queensland, Australia, where it originally lived on native fruit. When exotic horticultural species of fruit and vegetables were introduced into its native range, B. tryoni was exposed to a novel host range to which it readily adapted. It subsequently expanded its distribution to wide areas of eastern Australia where it has severe consequences for some crops. High levels of control and monitoring are required to ensure that major production areas are kept free from this native, invasive species. 184.108.40.206 Natural disasters Natural disasters affect the entry of invasive species. Cyclones (hurricanes) can result in the movement of organisms over abnormally long distances. Similarly, large-scale disturbance of landscapes can create conditions in which invasive organisms can establish, e.g. the spread of insect vectors or large-scale destruc-tion of land cover creates opportunities for establishment of weeds. In addition, natural disasters often generate emergency relief actions and the rapid import-ation of largely uncontrolled goods. The associated quarantine risks often lead to accidental introductions (see Section 1.4.2). 1.4.2 Accidental introductions There are many historical examples of accidental introductions, e.g. rodents via ships, weeds in fodder, and European woodborer in furniture. More recent examples include aquatic diseases introduced through ornamental fi sh and hyper-parasites introduced with biological control agents. The impacts of such accidental introductions can rival those of deliberate introductions. For example, there are many documented examples of rodents causing at least local extinction of certain bird species. Most accidental introductions enter via contaminants of commodities or organ-isms. Th ey can also result from the deliberate introduction of another species upon which they are parasites, e.g. parasitic mites of bumblebees introduced into Japan for pollination purposes where the parasitic mites moved from the imported spe-cies to native species where they have had a negative impact (Goka et al. 2006). 220.127.116.11 Trade Trade is the major pathway for short- and long-distance movement of small-to- large quantities of materials and goods. Over recent decades, there have been vast
6 | Invasive species management improvements in the capacity to rapidly move greater volumes, and an increased variety, of material. Organisms associated with trade goods no longer need to sur-vive for as long a period as they previously needed to in order to arrive in a viable condition at a destination. Hence, there is a signifi cant increase in the potential for trade to be a source of invasive species. As the primary objective of trade is profi t or economic benefi t, this often involves moving goods as fast as possible from source to outlet. This need is frequently in confl ict with quarantine measures designed to lower the likelihood of entry of invasive species, because the measures may be seen to impede the speed of movement of goods. This can result in a tendency to avoid these measures. Therefore, there is a need to develop pragmatic quarantine meas-ures, in conjunction with stakeholders, which are commensurate with the threats posed by the trade. If possible, these measures should be undertaken as close to the entry point into a country and as effi ciently as possible. If the quarantine measures are integrated into normal practices, there is a greater probability of a high level of compliance than if the measures cause change to nor-mal practices. However, there are circumstances where changes to normal prac-tices are unavoidable to achieve the required level of protection. It is important to remember that not only the goods themselves are potential pathways for invasive alien species, but also the conveyances by/on which they are transported, e.g. wood borers in packing crates. 18.104.22.168 Traditional movement of people and goods Traditional movement of people and goods are pathways that have existed for a considerable time, particularly between countries with land borders. These pathways can allow the entry of invasive alien species, including both acciden-tal introductions such as cattle diseases, and purposeful introductions such as food crops with weed potential. When establishing a quarantine system these movements should be given consideration but with an understanding that some may be diffi cult to manage. The objective is not necessarily the complete exclu-sion of traditional movements, which often encourages illegal trade. Rather, the need is to look at what goods (animals, foodstuff, plant material, and convey-ances) are involved, the areas through which they pass, the risks involved, and the available management options. Communities should be engaged to increase awareness of the risks and develop appropriate quarantine measures to reduce the risks. 22.214.171.124 Emergency food, disaster relief, and development aid Emergency food and disaster relief, and development aid, can be a source for the introduction of invasive species, e.g. stored product pests such as larger grain borer (Prostephanus truncatus), aquatic species, and weed seeds. Such aid often involves the rapid deployment of people, vehicles, goods, and products, and in many cases quarantine or preventative measures are intentionally or unintentionally ignored. Often there are few, if any, controls enforced when people, vehicles, and goods
Biosecurity and quarantine for preventing invasive species | 7 enter a country. Political interference can over-ride justifi ed safety measures. Thus, the risks of the introduction of invasive species are often substantially increased during such a process. It is predicted that the need for food aid is likely to increase with the effects of global warming with a resulting increase in risk of invasions. The application of controls in source countries probably has the greatest potential to lower the likelihood of entry of invasive species into recipient countries. 1.4.3 Deliberate introductions Deliberate introductions of alien species for any purpose, including pasture and genotype improvement, new crops, biological control, land rehabilitation (e.g. for erosion control or post-mining activities), leisure activities (e.g. gardening), the pet trade, hunting, research, agricultural or horticultural purposes can have wide reaching, and often unexpected, consequences. Hence, there should be careful consideration of impacts beyond those of the immediate focus of the introduction programme when undertaking a risk analysis before importation. A large number of invasive species have been human assisted at least in the fi rst instance, a process that has been going on for thousands of years. During the coloniza-tion of the New World, especially in the 1800s, there were proactive moves to intro-duce a greater range of species into new areas for food or utility, for ornament, as pets, or for hunting (acclimatization societies) to make the new lands ‘feel like home’. Birds were often introduced to control insect outbreaks and later on, mammalian preda-tors were introduced to control outbreaks of the previous ‘useful’ introductions. A few of those introduced to Africa, Australia, and New Zealand include common mynahs (Aves: Sturnidae: Acridotheres tristis), rabbits (Mammalia: Oryctolagus cuniculus), foxes (Mammalia: Canidae: Vulpes vulpes), stoats (Mammalia: Mustelidae: Mustela erminea), weasels (Mammalia: Mustelidae: Mustela nivalis), European starlings (Aves: Sturnidae: Sturnus vulgaris), sparrows (Aves: Passeridae: Passer domesticus), deer (Mammalia: Cervidae: Cervus spp.), lantana (Magnoliopsida: Verbenaceae: Lantana camara), prickly pear (Magnoliopsida: Cactaceae: Opuntia spp.), pasture grasses (Liliopsida: Poaceae), goats (Mammalia: Bovidae: Capra hircus), and pigs (Mammalia: Suidae: Sus spp.). Many of these introductions, especially food plants, have been critical to the new colonies. Some introductions, when undertaken with appropriate consideration of the potential off -target impacts, can be highly benefi cial, such as biological control agents. A major trap for those proposing to import new organisms is that most spe-cies are normally not considered invasive in their home range. When introduced to a new range, these same species, by adaptation to new hosts or niches, have resulted in drastically altered habits and ecosystems, including the extinction of some native species. Th e consequences of many of the above introductions still have major impacts today. 126.96.36.199 Biological control Biological control usually involves the deliberate introduction and release of new organisms into areas, often in a repetitive manner. The objective of quarantine
8 | Invasive species management systems is to prevent the entry of new organisms that can have a negative impact and, as such, the release of biological control agents is contrary to most quarantine measures. Just because an organism is labelled as a biological control agent does not automatically mean that it will be safe or benefi cial in all circumstances. Even though an organism may have been used successfully and safely as a biological con-trol agent in a particular target area, it does not necessarily mean it will be safe in another ecological area. An example of this is with the highly successful use of the prickly pear moth, Cactoblastis cactorum in Australia to control prickly pear (Dodd 1940), where, even 70 years after initial release, it is still controlling prickly pear in that country. This same species of moth has accidentally entered the USA where it is an invasive pest (Hight et al. 2002; Vigueras and Portillo 2002; Zimmermann et al. 2002), and threatens species of cacti in their area of origin and livelihoods of subsistence farmers. This does not discount from the usefulness of this species as a safe biological control agent, provided appropriate non-target testing has been undertaken as well as consideration of the possible affects of this species in areas outside of the release areas, i.e. ability of this species to disperse (or be transported) to other geographic areas. Hence, when releasing biological control agents, if a country has land borders with another country or is in close proximity to another country, then potential impact of the biological agent in those areas should be considered. 188.8.131.52 Plant introductions Plants have been introduced around the world in an attempt to improve prod-uctivity in many areas. However, signifi cant numbers of these plants have either not been particularly useful or become invasive weeds. For example, in north-ern Australia, 463 pasture species of legumes and grasses were introduced for pasture improvement between 1947 and 1985; only four species proved useful with no invasive consequences, 17 species were proved useful as well as having weedy characteristics that caused problems for some sectors, and a further 60 species are considered invasive and as having no useful characteristics (Lonsdale 1994).1 Other examples of species introduced for commercial reasons include pines, acacias, and eucalypts, which form the basis of commercial plantation industries in many countries. However, in some areas outside of their native ranges, these introduced species have become invasive. For example, in South Africa in climatically suitable areas all three groups have become invasive (Rouget et al. 2002). Many ornamental plants that have been deliberately introduced into various areas around the world have become highly invasive. Some continue to be promoted in various areas as ornamental species. Part of the problem is that the combination of hardiness and attractiveness makes them desirable in horticulture because they require little maintenance to produce sometimes spectacular fl oral displays. One 1 These fi ndings eventually resulted in a weed risk assessment system for the introduction of plants into Australia (Pheloung et al. 1999).
Biosecurity and quarantine for preventing invasive species | 9 such species is Lantana camara. Th is species originally came from Central and South America, it now occurs throughout most tropical and subtropical areas in the world (e.g. Asia, Australia, the pacifi c islands, Africa). Lantana camara has attractive fl owers and thrives in a broad range of temperatures, soil types, and rain-fall ranges. It is a major weed of disturbed areas including agriculture and areas of signifi cant environmental value. It is tolerant of slashing and chemical controls and hence is diffi cult to control. It has been the subject of biological control eff orts for many years; these have, at best, only achieved partial success. It continues to expand its range and become denser in areas where it already exists. It is diffi cult to eradicate and takes considerable persistence to do so, and vigilance to prevent reinfestation. Th e recent trend for introducing biofuel crops raises the spectre of new weed invasions, especially onto marginal land in the tropics or the encouragement of the clearing of virgin forests to plant alien species, hence creating signifi cant areas of ecological disturbance. 184.108.40.206 Smuggling Deliberate illegal introductions can have signifi cant consequences, not only from the species smuggled, but also other pests and diseases entering with the material. This can be because of ignorance of the consequences or deliberate avoidance of extremely strict quarantine regulations. Hence, to lower the likelihood of such instances there is a need to facilitate movement of material wherever possible, and where this is not possible to work with people and provide reasons and information as to why it is so. Therefore, the engagement of populace and good communication is critical to a robust quarantine system and indeed all aspects of biosecurity. Another factor that complicates the issue of quarantine or biosecurity is the pos-sibility of malicious or deliberate introduction of species in an attempt to create damage or fear e.g. the possible release of zoonotic diseases or widespread distribu-tion of crop diseases. Th is risk should be considered when conducting the overall risk analyses of threats to a country. 1.5 Actions The types of action that can be taken to reduce the risk of entry/establishment of invasive species fall into three broad categories. These are: pre-border actions— those actions taken outside a country or region; border actions; and post-border emergency actions. Each category has two main components—physical (e.g. infrastructure, materials, fi nance) and human (e.g. legislation, procedures, skills). It should be noted that to establish and maintain quarantine system takes the ongoing commitment of physical and human resources. Th e objective of quarantine systems is usually to lower the risk or prevent the entry of identifi ed unwanted organisms. When a quarantine system is developed, various aspects should be considered. Th ese include understanding of the degree
10 | Invasive species management of natural biological isolation of the country, infrastructure capacity, the legal and political situation, available technical expertise, communication capacity, and personnel capabilities. Th ere are generic similarities between most quaran-tine systems, but every quarantine system should be developed specifi cally for the particular circumstances that prevail within a country. In the case of plant quaran-tine systems, ISPM 20 (FAO 2004b) provides general guidance for the elements of an import system for plants—these are applicable to most systems and can be adapted to lower the risk of entry of invasive species. See Fig. 1.1 for a diagram of assessment and management of risks associated with invasive species In quarantine systems, actions with regards to particular species can take place before the border (pre-entry), at the border (entry), or as a reaction to the detection of an invasive species (emergency actions). 1.5.1 Pre-entry There is a need to identify the organisms or groups of organisms that pose risks and assess their potential impacts. This will enable appropriate guidance and con-tingency resources for detecting or controlling them should they enter or escape. When undertaking a risk analysis or assessment, issues that are useful to consider include those mentioned in Section 1.1, in particular the pathway/s via which an organism is most likely to arrive. Control of pathways of entry of invasive organ-isms provides the best opportunity to prevent the entry. Risk mitigation measures prior to entry include: pre-export inspection; pre-export treatments; fi eld treatments; selection of material from areas free of the invasive species or areas where there is low populations of the invasive species of concern; or treatment of goods that may provide a pathway for the target invasive species at discharge at the airport/port of entry. Identify regulations needed to enable and support actions Identify possible risk mitigation actions Surveillance measures applied before entry, at entry, after entry Identify vulnerable areas including those from non-natural entry: Inspection points (all entry points— road, air, sea) Risk assess Deploy resources to high priority areas Fig. 1.
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