# Invasive Non-Native Species: Background and Issues for Congress > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/crs%3ARL30123 ## Record - **Collection:** Congressional research report - **Document type:** CRS Report - **Published:** November 25, 2002 - **Citation:** RL30123 ## Text Order Code RL30123 Report for Congress Received through the CRS Web Invasive Non-Native Species: Background and Issues for Congress Updated November 25, 2002 M. Lynne Corn, Eugene H. Buck, Jean Rawson, Alex Segarra, and Eric Fischer Resources, Science, and Industry Division Congressional Research Service ˜ The Library of Congress Invasive Non-Native Species: Background and Issues for Congress Summary For the first few centuries after the arrival of Europeans in North America, plants and animals of many species were sent between the two land masses. The transfer of non-natives consisted not only of intentional westbound species ranging from pigs to dandelions, but also intentional eastbound grey squirrels and tomatoes. And for those centuries the remaining non-native species crossing the Atlantic uninvited and often unwelcome, were ignored if they were noticed at all. National focus on non-native species arose in the 19th Century, primarily over losses in agriculture (due to weeds or plant diseases), the leading industry of the time. A few newly-arrived non-natives, and new estimates of adverse economic impacts exceeding $100 billion annually, have sharpened that focus. Very broadly, the unanswered question regarding non-native species is whose responsibility is it to ensure economic integrity and ecological stability in response to the actual or potential impacts of non-native species? As this report shows, the current answer is not simple, and may be “no one.” It may depend on answers to many other questions: Is the introduction deliberate or accidental? Does it affect agriculture? By what pathway does it arrive? Is the potential harm from the species already known? Is the species already established in one area of the country? Finally, if the answers to any of these questions are unsatisfactory, what changes should be made? The specific issue before Congress is whether new legislative authorities and funding are needed to address issues of non-native species and their increasing economic and ecological impacts. Such legislation could affect domestic and international trade, tourism, industries dependent on bringing in non-native species, those dependent on keeping them out, and finally, the variety of natural resources which have little direct economic value and yet affect the lives of a broad portion of the public. In the century or so of congressional responses to harmful non-native species, the usual approach has been an ad hoc attack on the particular problem, from impure seed stocks to brown tree snakes on Guam. A few notable attempts have begun to address specific pathways (e.g., ship ballast water), but no current law addresses the general concern over non-native species and the variety of paths by which they enter this country. A 1998 Executive Order takes a step in bringing together some of the current authorities and resources to address a problem that has expanded with both increasing world trade and travel and decreasing transit time for humans and cargo. Bills have been introduced on this subject in the 105th, 106th, and 107th Congresses. This report compares an approach based on a species-by-species assessment, vs. one based on pathways of entry. It also assesses the choice of an emphasis on prevention vs. post hoc control and intra-state quarantine. It describes existing federal laws and federal agency roles, federal interagency cooperation, and the federal interaction with state governments. Finally, it outlines effects, costs, and issues surrounding 47 selected harmful non-native species. Contents Overview and Current Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 The Size of the Threat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Dollar Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Major Laws and Executive Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Executive Order 13112 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Preliminary Options for A Complex Problem . . . . . . . . . . . . . . . . . . . . . . . . 4 Predicting an Invasion: Black and White? . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Threat of Harmful Non-Native Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Numbers of Non-Native Species in the United States . . . . . . . . . . . . . . . . . . 9 A Brief History of Introductions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Geographic Origins of Non-Native Species . . . . . . . . . . . . . . . . . . . . . . . . . 11 Pathways of Invasion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Basic Methods of Pest Prevention and Control . . . . . . . . . . . . . . . . . . . . . . 14 Baits and Attractants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Traps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Fumigants, Repellents, and Barriers Designed for Confined Spaces . . 16 Herbicides and Pesticides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Biological Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Bounties and Commercial Exploitation . . . . . . . . . . . . . . . . . . . . . . . . 19 Cultivation Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Mechanical Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Site Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Unusually Susceptible Habitats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Available Estimates of Costs and Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Industries That Benefit from Non-native Species . . . . . . . . . . . . . . . . . . . . 23 Harm to the Natural Environment: Diffuse Responsibilities . . . . . . . . . . . . 24 Federal Laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Lacey Act . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Animal Damage Control Act . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Federal Seed Act . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 National Environmental Policy Act of 1970 (NEPA) . . . . . . . . . . . . . . . . . 27 Endangered Species Act (ESA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Federal Noxious Weed Act . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Nonindigenous Aquatic Nuisance Prevention and Control Act . . . . . . . . . . 29 National Invasive Species Act . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Alien Species Prevention and Enforcement Act of 1992 (ASPEA) . . . . . . 32 Wild Bird Conservation Act of 1992 (WBCA) . . . . . . . . . . . . . . . . . . . . . . 32 Hawaii Tropical Forest Recovery Act of 1992 . . . . . . . . . . . . . . . . . . . . . . 32 Plant Protection Act of 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Executive Order 13112 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Agency Responsibilities: Programs and Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Interagency Efforts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 National Invasive Species Council . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Aquatic Nuisance Species (ANS) Task Force . . . . . . . . . . . . . . . . . . . 39 Federal Interagency Committee for Management of Noxious and Exotic Weeds (FICMNEW) . . . . . . . . . . . . . . . . . . . . . . . . . 39 Department of Agriculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Agricultural Research Service (ARS) . . . . . . . . . . . . . . . . . . . . . . . . . 39 Animal and Plant Health Inspection Service . . . . . . . . . . . . . . . . . . . . 40 Cooperative State Research, Education, and Extension Service (CSREES) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Economic Research Service (ERS) . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Farm Service Agency (FSA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Forest Service (FS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Natural Resources Conservation Service (NRCS) . . . . . . . . . . . . . . . . 42 Department of Commerce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 National Oceanic and Atmospheric Administration (NOAA) . . . . . . . 42 National Sea Grant College Program . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Department of Defense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Army Corps of Engineers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Department of the Interior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Bureau of Indian Affairs (BIA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Bureau of Land Management (BLM) . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Bureau of Reclamation (BOR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Fish and Wildlife Service (FWS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Geological Survey (USGS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 National Park Service (NPS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Office of Surface Mining Reclamation and Enforcement (OSM) . . . . 47 Department of State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Department of Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Coast Guard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Federal Aviation Administration (FAA) . . . . . . . . . . . . . . . . . . . . . . . 48 Federal Highway Administration (FHwA) . . . . . . . . . . . . . . . . . . . . . 49 Executive Office of the President . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Council on Environmental Quality (CEQ) . . . . . . . . . . . . . . . . . . . . . . 49 Office of Science and Technology Policy (OSTP) . . . . . . . . . . . . . . . 49 Office of the United States Trade Representative (USTR) . . . . . . . . . 49 Independent Agencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Environmental Protection Agency . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 National Science Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Smithsonian Institution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 State Efforts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 International Efforts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Coverage of Laws or Policy: Actions and Approaches . . . . . . . . . . . . . . . . . . . . 55 Federal Agency Actions: A Patchwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Interaction of State and Federal Programs . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Approaches to Regulation: Species-by-Species vs. Pathways . . . . . . . . . . . 58 A Few Legislative or Policy Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 A Gallery of Harmful Non-Native Plants and Animals . . . . . . . . . . . . . . . . . . . . 63 Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Whirling Disease, Myxobolus cerebralis . . . . . . . . . . . . . . . . . . . . . . . 63 Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Leafy Spurge, Euphorbia esula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Purple Loosestrife, Lythrum salicaria . . . . . . . . . . . . . . . . . . . . . . . . . 64 Spotted, Diffuse, and Russian Knapweed, Centaurea maculosa, C. diffusa, Acroptilum repens, and Yellow Starthistle, Centaurea solstitialis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Melaleuca, Melaleuca quinquenervia . . . . . . . . . . . . . . . . . . . . . . . . . 65 Water Hyacinth, Eichhornia crassipes . . . . . . . . . . . . . . . . . . . . . . . . 65 Salt Cedar, Tamarix (several species) . . . . . . . . . . . . . . . . . . . . . . . . . 65 Hydrilla, Hydrilla verticillata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Cordgrass, Spartina sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Caulerpa, Caulerpa taxifolia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Arthropods: Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Formosan Termite, Coptotermes formosanus . . . . . . . . . . . . . . . . . . . 67 Imported Fire Ants, Solenopsis invicta and S. richteri . . . . . . . . . . . . 68 Argentine Ant, Linepithema humile . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Africanized Honeybee, Apis mellifera scutellata . . . . . . . . . . . . . . . . 69 Asian Longhorned Beetle, Anoplophora glabripennis . . . . . . . . . . . . 69 Asian Tiger Mosquito, Aedes albopictus . . . . . . . . . . . . . . . . . . . . . . . 70 Mediterranean Fruit fly, Ceratitis capitata . . . . . . . . . . . . . . . . . . . . . 71 Other Arthropods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Honeybee Mites, Acarapis woodi and Varroa jacobsoni . . . . . . . . . . 72 European Green Crab, Carcinus maenas . . . . . . . . . . . . . . . . . . . . . . . 72 Chinese Mitten Crab, Eriocheir sinensis . . . . . . . . . . . . . . . . . . . . . . . 73 Rusty Crayfish, Orconectes rusticus . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Spiny Water Flea, Bythotrephes cederstroemi . . . . . . . . . . . . . . . . . . . 74 Mollusks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Zebra Mussel, Dreissena polymorpha . . . . . . . . . . . . . . . . . . . . . . . . . 74 Brown Mussel, Perna perna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Asian River Clam, Corbicula fluminea . . . . . . . . . . . . . . . . . . . . . . . . 75 New Zealand Mud Snail, Potamopyrgus antipodarum . . . . . . . . . . . . 75 Vertebrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Sea Lamprey, Petromyzon marinus . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Alewife, Alosa pseudoharengus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Round Goby, Neogobius melanostomus . . . . . . . . . . . . . . . . . . . . . . . 76 European Ruffe, Gymnocephalus cernuus . . . . . . . . . . . . . . . . . . . . . . 77 Common Carp, Cyprinus carpio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Walking Catfish, Clarias batrachus . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Snakeheads, Channidae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Rainbow Trout, Oncorhynchus mykiss . . . . . . . . . . . . . . . . . . . . . . . . 78 Lake Trout, Salvelinus namaycush . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Coqui, Eleutherodactylus coqui . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Brown Tree Snake, Boiga irregularis . . . . . . . . . . . . . . . . . . . . . . . . . 79 Indian Mongoose, Herpestes auropunctatus . . . . . . . . . . . . . . . . . . . . 79 Nutria, Myocastor coypus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Appendix A: List of Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Appendix B: Federal Agency Funding for Invasive Species . . . . . . . . . . . . . . . 83 List of Figures What’s In A Name? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 U.S. As A Source of Non-Native Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Homeland Security and Invasive Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 List of Tables Estimated Numbers of Non-Native Species in the United States . . . . . . . . . . . . 10 Invasive Non-Native Species: Background and Issues for Congress Overview and Current Status The Size of the Threat Brown tree snakes from the western Pacific threaten power utilities and communications on Guam and the Northern Marianas, and seem ready to invade Hawaii and harm its enormous tourism industry. Zebra mussels from eastern Europe clog intakes for urban water supplies and nuclear power plants in the Great Lakes and the Mississippi basin. Formosan termites devastate living trees and historic buildings in New Orleans’ French Quarter. Leafy spurge slashes the forage value of western grazing land, thereby creating precipitous drops in land value. Voracious snakehead fish from China appear in a pond in Maryland, precipitating drastic measures by state officials to keep them from spreading and destroying many of the region’s freshwater fish. To continue with a full list of the damaging effects of harmful non-native plants and animals risks sounding like hyperbole. Only in fairly recent years have many people realized that various areas of the country share problems that are similar in outline if not in detail. Impacts have been particularly severe on agriculture. The globalization of trade, the increased speed of travel, the massive volume of cargo shipments, and rising tourism all combine to increase the chance of more accidental introductions. Moreover, trade in exotic plants and animals that would have been impractical when voyages took days or weeks, now becomes practical when shipment times are only a fraction of that. Some of the species in the horticulture and exotic pet trades may escape or be released in the wild by accident or when owners tire of them. All 50 states and all of the territories have at least some non-native plants and animals. A few (e.g., Hawaii, Florida, Louisiana, Great Lakes states, California) have so many harmful non-natives as to cause major ecological and economic damage to a variety of locations and industries. Problems with terrestrial non-native species tend to be more severe in the southern half of the country in terms of total numbers of non-native species. Aquatic invasives have created more evenly distributed problems. Dollar Impacts Estimating the total economic impact of harmful non-native species is extremely difficult. No federal agency accumulates such statistics comprehensively. One CRS-2 widely cited estimate put damage at $123 billion annually.1 Including cost of control, damage to property values, health costs, and other factors, the following are the costs of selected species:2 Leafy spurge (plant) — over $100 million annually Purple loosestrife (plant) — $45 million annually Formosan termite — $1 billion annually (including several hundred million dollars in New Orleans alone) ! Fire ant — about $2 billion annually (including $300 million in Texas alone) ! European green crab — about $44 million annually ! Zebra mussel — More than $750 million over 10 years (only for cleaning water intake pipes, filtration equipment, power generating equipment, etc., but not damage to docks, recreational or commercial boats, or other problems) ! Asian river clam — $1 billion annually ! Sea lamprey — $10-15 million annually for control only ! Brown tree snake — $1 million annually on Guam in power outages alone ! ! ! Many impacts would be extremely difficult to measure in monetary terms. The West Nile virus has had a severe impact on populations of some wild birds, which are a major focus of recreation for millions of Americans. The introduction of lake trout into Yellowstone Lake (see Gallery, below), for example, is likely to have profound effects on populations of native cutthroat trout and, as a result, on grizzly bears, bald eagles, and other species. The presence of honeybee mites (see Gallery) is more problematic. On the one hand, crops pollinated by honeybees (itself a nonnative species) will be more difficult to raise. On the other, species of native bees (bumble bees, carpenter bees, solitary bees, etc.), which are unaffected by the mites, may benefit from the absence of competition, and the presence of mites may be slowing the northward spread of Africanized honeybees, also a non-native species. And zebra mussels – one of the most costly invasives to date – have benefitted water quality in the Great Lakes region (see Gallery). 1 David Pimentel, Lori Lach, Rodolfo Zuniga, and Doug Morrison. “Environmental and Economic Costs of Nonindigenous Species in the United States.” BioScience, January 2000, Vol. 50, p. 53-65. It represents one of the few attempts to date to provide comprehensive cost estimates. (Hereafter referred to as Pimentel report.) Costs estimates in the study included weeds, crop disease, rats, insect pests, non-native diseases of humans, zebra mussels, and a variety of other species and categories. Domestic and feral cats and dogs were included, and accounted for 4.9% and 0.1% of the total, respectively. Some have criticized the report as inflated, or as failing to count benefits of other introduced species. 2 Each of these species is covered, in this order, in A Gallery of Invasive Non-native Plants and Animals at the end of this report; see these entries for documentation of economic impacts. CRS-3 Major Laws and Executive Order Because the problem of non-native species has continued to present itself as a series of seemingly disconnected crises, legislation has also become a patchwork, as each crisis was addressed. The laws addressing threats to agriculture (for centuries a well-developed North American industry whose risks from non-native invasions are relatively clear) tend to be more developed than laws protecting other industries, or ecosystems. In consequence, agencies whose mission is to address those risks are also better developed. Yet even there, responsibilities to protect agriculture from non-natives which are established in some regions but not others, are diffuse, shared, or even lacking. Moreover, the enormous volume of trade makes the burden on understaffed federal inspection systems so severe as to permit What’s In A Name? only limited or cursory Many names have been used to describe inspections, and force a strong species that are able to survive and reproduce reliance on self-reporting by outside the habitats where they evolved or spread importers of living and nonnaturally. Among them are alien, exotic, injurious, living cargo. Laws protecting the natural ecosystems on which such industries as tourism, the electric power industry, or city water supplies depend are far less developed. In some important instances, such laws scarcely exist at all. A state agency which wishes to bring in a sport fish from another continent to benefit its anglers may face few obstacles in doing so, much less a burden of proof to show that the action will not harm other economic interests, natural resources, or ecosystems. introduced, invasive, nonindigenous, non-native, and noxious. Alien tends to be applied to species from other regions that are also harmful and likely to proliferate wildly in their new habitat. Injurious, invasive, and noxious are generally used synonymously and are not confined to species outside of their normal range. These terms are applied to species that proliferate wildly, whether native (like white-tailed deer and barnacles) or nonnative (like leafy spurge and brown tree snakes). In the legal arena, these terms are found in various laws and defined in various ways. This report generally uses the term non-native to emphasize the geographic origin of these species, but the term invasive is also used in deference to its increasing use among federal agencies. This paper focuses on those non-native species which have caused or seem likely to cause substantial economic harm. The authors recognize that many species (e.g., cattle, olives, wheat, tulips, etc.) were introduced with either little known adverse ecological impact, or with sufficient net benefits to make it likely that most people would not consider them harmful. No comprehensive U.S. law addresses imports of nonnative species (see Federal Laws below for a summary of current statutory provisions). Some areas of interest lack laws altogether. No obligation lies generally with those importing living organisms (other than those already known to threaten agriculture) to show that the imported species is safe. Some laws force the burden of proof in the other direction: an import is deemed safe unless it is on a list of organisms known to be harmful. Special laws to control imports of exotic aquarium fishes or pets, and the disposal of those pets once owners tire of them, are lacking, or may be focused on some other issues (e.g., CRS-4 effects on populations of wild birds in the exporting country rather than in the United States). Executive Order 13112. In response to rising concern, especially in southern and western states plus Hawaii, President Clinton issued Executive Order 13112 on Invasive Species (64 Fed. Reg. 6183, Feb. 8, 1999), revoking and replacing President Carter’s 1977 Executive Order 11987 on exotic species.3 The Executive Order seeks to prevent the introduction of invasive species,4 provide for their control, and minimize their impacts through better coordination of federal agency efforts under a national invasive species management plan developed by an interagency National Invasive Species Council. The Order directs all federal agencies to address invasive species concerns as well as refrain from actions likely to increase invasive species problems. The National Invasive Species Council, supported by an advisory committee, was directed to develop recommendations for international cooperation, promote a network to document and monitor invasive species impacts, and encourage development of an information-sharing system on invasive species. (See National Invasive Species Council below for more information.) Preliminary Options for A Complex Problem Non-native species introductions can be divided into those which were intentional, or at least known by the person bringing in the living organisms, and those whose arrival was probably not known to the persons involved. While there may be disagreement over which species should be excluded among the many species whose entry is sought, there appears to be no constituency for unintentional imports. Rather, opposition results from the effects of regulations on trade or travel generally that might arise from efforts to prevent introductions. Therefore research on which pathways pose the greatest risks, and on the least intrusive mechanisms to reduce those risks, could offer substantial benefits with reduced harm to trade and travel. However, with the possible exception of controls on ballast water and some agricultural pathways, little has been done systematically to identify or control additional high risk pathways. Congress may wish to consider requiring studies to (a) identify other high risk pathways; (b) identify (or create) suitable methods to prevent further introductions via these pathways; and (c) investigate methods to reduce inconvenience of control measures to travelers and shippers using those pathways. Untreated wood used in pallets, packing material, crates, and barrels; airline cargo holds; ship hulls, holds and ballast tanks; used tires, etc. are among possible targets for broader risk assessment or controls. In contrast, intentional introductions present a different set of problems. Because many deliberate releases of non-native organisms have not been wellplanned and have not taken into account the potentially injurious nature of the exotic 3 For more information on the legal status of Executive Orders, see CRS Report 95-772 A, Executive Orders and Proclamations. 4 Invasive species are defined in §1 of the Executive Order as “alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” CRS-5 species, nor compared the potential risks with expected gains, some organizations have developed guidelines and codes of practice. The American Fisheries Society,5 the International Council for the Exploration of the Sea, the World Resources Institute,6 and the Food and Agriculture Organization of the United Nations7 have prepared such guidelines to assist regulatory bodies and other groups in determining whether an introduction is justified, and then to advise them on what to do after an introduction is approved. These guidelines complement the legislation described later in this report by providing a conceptual framework for determining whether the risk of introduction is acceptable, and then suggesting quarantine, monitoring, and/or adaptive management if an introduction is approved. Components of these guidelines have been incorporated in national legislation in the United States and elsewhere. Rapid response to news of a recent introduction of an invasive species is also an area being considered for improvement. In this respect, lessons might be learned from the National Interagency Fire Center (NIFC), primarily under the management of the Bureau of Land Management. Response to wildfires faces many of the same problems of haste, technical needs, and interagency and intergovernmental coordination. All federal land managing agencies participate in the NIFC, and a great deal of the program focuses on work with tribal, state, and local governments to bring many resources to bear on major fires. Somewhat similar problems are also faced at the federal Center for Disease Control and Prevention in Atlanta. Either program might provide models for congressional consideration. Predicting an Invasion: Black and White? Federal laws have tended to focus on exclusion, or “black lists,” i.e., on species that have already been shown to be harmful (anything not on the list is allowed), in contrast to a “white list” (anything not on the list is excluded). The black list can be prepared in various ways, but is usually made up of species already shown to cause serious damage to fisheries, endangered species, or (especially) agriculture.8 An alternative approach would be to attempt to predict potential harm before a species’ arrival. The prediction would be based on known characteristics of a species, such as how it reproduces, the number of seeds or offspring, etc. A central dilemma, however, is the difficulty in making this prediction. What characteristics of seed dispersal, nesting, food and host preferences, etc., are most likely to lead to exuberant proliferation and result in economic and ecological harm? Even more fundamentally, of the many millions of species on the planet, which ones should be tested? For example, it seems logical that, all else being equal, plants 5 [http://www.fisheries.org/Public_Affairs/Policy_Statements/ps_15a.shtml] 6 [http://www.wri.org/biodiv/b12-gbs.html#guidelines] 7 Devin M. Bartley, R.P. Subasinghe, and D. Coates, Framework for the Responsible Use of Introduced Species, EIFAC/XIX/96/inf. 8. Report of the 19th Session, (Dublin, Ireland: European Inland Fisheries Advisory Commission, 1996). 8 It should be noted that black lists do not readily address introductions by persons who are unaware that they are bringing in non-native organisms. CRS-6 producing many seeds will be more invasive than those producing few seeds. The problem is that all else rarely is equal: a variety of factors affect “invasiveness.” The abundant seed producer may require a special pollinating insect; the newly arrived plant with few seeds may leave behind its major herbivores, etc. A host of other factors may complicate prediction. No evidence to date has identified a suite of features in plants or animals that seems to be a truly reliable predictor of invasiveness, and thus many experts view all importations as suspect. One observer argued that a somewhat reliable predictor is what he called “propagule pressure.”9 In very simple terms, this means that those species that “attempt” invasions (arrive in large numbers) most frequently and/or with the largest number of arriving individuals are most likely to have some success at invading. Scientists continue to model various factors which might contribute to invasiveness. Nonetheless, many scientists will likely prefer the strictest possible exclusionary policies, including white lists, because they lack confidence in these models. In contrast, a number of industries depend in some respect on introductions of non-native species. These industries include florists as well as the horticulture, pet, and aquarium industries. They argue that a white list approach would exclude many species that were unlikely to cause harm, or else would require inordinate economic burdens on their industries to prove that a given imported species was safe. Further, paperwork to prove that an imported species was indeed one that was on the white list, could be burdensome as well. These groups strongly prefer a black list approach. Whether a list is white or black, however, still implies that the importers actually know they are importing living organisms. An effort to prevent unintentional introductions would be compatible with any shade of list. 9 Mark Williamson, Biological Invasions (London: Chapman & Hall, 1996), Chapter 2, p. 28-54. CRS-7 Threat of Harmful Non-Native Species A variety of abundant non-native species have had severe economic impacts on U.S. industries and the natural environment. The increasing number of introductions and greater estimates of their cost are causing pressure on Congress to develop new responses to the problem. For example, according to a 1993 study by the Office of Technology Assessment OTA), just 79 of over 4,500 non-native plants and animals in the United States caused over $97 billion in damage between 1906 and 1991.10 A more recent study estimated current damage from all of the species examined at $123 billion annually.11 Damage varies by species, and can span an enormous range of effects, including power outages; loss of farmland property value; contamination of grain; spread of disease; increased operating costs; loss of irrigation water; collapse of buildings; competition with native plants; loss of sport, game, or endangered species; ecosystem disturbance; etc. Some non-native plants have been notorious for years for causing both economic and ecological damage; kudzu, melaleuca, cordgrass, salt cedar, purple loosestrife, spotted knapweed, and Russian thistle are just a few examples of unwanted plants now causing ecological and economic harm in large areas of the United States. Their damage includes lowering water tables, poisoning humans and livestock, decreasing crop yields, and increasing pest control costs. A serious infestation can cause substantial losses in property values.12 Non-native invertebrate pests are also well-known: gypsy moths, Japanese beetles, Asian longhorned beetles, Asian tiger mosquitoes, fire ants, Africanized honeybees, and zebra mussels are among the most well-known. Introduced vertebrate pests (e.g., walking catfish, lake trout, cane toad, brown tree snakes, monk parakeet, starlings, feral goats, bighorn sheep, nutria, rats, etc.) can also have serious economic and ecological impacts. These effects can also include the introduction of various human parasites and diseases.13 10 U.S. Congress. Office of Technology Assessment. Harmful Non-Indigenous Species in the United States. OTA-F-565. Washington, DC: U.S. Government Printing Office, September 1993, p. 3-5. (Hereafter referred to as “OTA Report.”) 11 Pimentel report. This study covered a broader array of species than the OTA report, and extrapolated estimates from available sources. (See Pimentel report for precise assumptions.) The arrival of more species since 1991 and a larger economy alone would be expected to increase damage substantially. 12 A serious infestation of leafy spurge (Euphorbia esula) on an Oregon ranch caused a drop in property value from about $125-$150 per acre to $22 per acre over 10 years. (Federal Interagency Committee for the Management of Noxious and Exotic Weeds. Invasive Plants: Changing the Landscape of America. Washington, DC, p. 27; hereafter referred to as the “FICMNEW report.”) 13 While the transfer of human pathogens such as smallpox, syphilis, measles, AIDS, and malaria from continent to continent has enormous human, ecological, and economic consequences, human pathogens and parasites will not be covered in this report, though a few disease vectors (species that can transmit diseases to other organisms, but are not themselves pathogens) are mentioned. CRS-8 In some of these cases (e.g., kudzu, melaleuca, gypsy moths, Africanized bees, zebra mussels, and starlings), the source of the introduction is either known or strongly suspected. Introducers of some species, such as kudzu, melaleuca, and starlings, actually intended that their imports proliferate in the wild. Their purposes ranged from the practical (kudzu for erosion control) to the quixotic (starlings for a purported desire to bring all of the birds mentioned in Shakespeare’s works to the United States). Whatever the motive, society itself was the loser in the importers’ Faustian bargains as the organisms proliferated to the detriment of the economy, native fauna and flora, and ecosystems. Had they foreseen the damage these species would later cause, governments at all levels would probably have worked to prevent these introductions. Introductions of non-native species may be intentional or unintentional. Some intentional introductions produced benefits (or at least low levels of harm), as in the case of the ring-necked pheasant, a game bird native to Asia. Unintentionally introduced species may be present for years or decades before their presence is even recognized, and the harm that they do, if any, is measured or observed.14 However, catastrophic results can come from both accidental introductions (e.g., zebra mussels), and intentional introductions (e.g., hogs to Hawaii). A wide variety of intentional introductions have had effects which, even if harmful to natural ecosystems or biodiversity, have produced economic benefits sufficient to cause acceptance of collateral damage. These include such food sources as cattle, wheat, honeybees, kiwi fruit, and soybeans, and such ornamentals as tulips, chrysanthemums, and dawn redwoods, to name only a few. In each case the introduction of these species was very much intentional and their propagation was more or less controlled. The economic benefits conveyed by these species are vast, and probably exceed the $123 billion figure cited above for the annual costs of nonnative species.15 U.S. agriculture would have a far different appearance if it were limited to the several dozen food crops known to have been cultivated in North America before 1492 rather than the hundreds of crops grown today. These nonnative crops and their benefits are not the focus of this report, but should not be forgotten in discussions of those imported species which cause serious harm. However, even in the case of non-native species conveying obvious benefits to humans, the introductions of non-natives are not without ancillary dangers, sometimes to the interests of those importing the target species: cattle can bring in seeds and new diseases, tubers can bring in insect pests, and soil from roots or hooves can harbor diseases for native plants. There may be damage to local ecosystems as they are deliberately modified to accommodate new plants or animals; in many cases (e.g., tulip cultivation or chicken ranches), society has accepted 14 Measurements of the number of non-native species that do no harm is exceedingly difficult: by being innocuous, they escape study. Similarly, Kentucky blue grass (Poa pratensis, which, despite its common name, may have been an early import from Europe) now serves as important forage for native herbivores in much of the United States, and its benefits are equally hard to measure. 15 No estimates of the benefits of desirable non-native species were found. A short discussion of industries and interests benefitting directly from non-natives is given on p. 23. CRS-9 conversion of land to support these species. On the other hand, controversies over grazing rights for such non-natives as cattle and sheep show that acceptance is not automatic. Examples of these attendant risks and problems will be considered below. This paper will focus on species prone to (a) escaping human control or whose potential for escape is unclear, or (b) harboring or transporting other undesirable species. Predicting either of these risks is one of the most difficult problems in addressing invasions by non-native species. Numbers of Non-Native Species in the United States If a new kind of tree grows in the forest, no one hears of it, at least not for a long time. When new organisms are introduced to a new site, they must find conditions adequate to their needs, depending on the biology of the species (e.g., food, rainfall, temperature, or mates), and must avoid predators and diseases. As a result, scientists agree, the great majority of biological introductions, whether caused by humans or occurring naturally, tend to fail. Of those that succeed, a small fraction become serious pests. A new species can exist in an area for decades without being noticed. For that reason, the number of non-native species counted in an area (if such counts are made) is likely to underestimate of the number of non-native species in the area. So vast is this “bioinvasion” (as some have termed it), that only rough estimates can be made of the numbers of non-native species now in North America, much less the rest of the world. The 1993 OTA study cited above summarized information known then on the number of non-native species in the United States. (See Table 1.) It divided the species into those of foreign origin, and those of U.S. origin that had been introduced outside of their native ranges. As the OTA study noted, “These numbers should be considered minimum estimates. Experts believe many more [non-native species] are established in the country, but have not yet been detected.” A more recent report estimated 30,000 non-native species in the United States.16 16 Pimentel report. CRS-10 Table 1. Estimated Numbers of Non-Native Species in the United States Species with origins outside the United States Category Number Plants >2000 unknown Terrestrial vertebrates 142 ~6% Insects and arachnids >2000 ~2% Fish 70 ~8% Mollusks (non-marine) 91 ~4% Plant pathogens 239 unknown Total Percent of total species in United States by category >4542 Species of U.S. origin introduced beyond their natural ranges Plants unknown unknown Terrestrial vertebrates 51 2% Insects and arachnids unknown unknown 57 17% Mollusks (non-marine) unknown unknown Plant pathogens unknown unknown Fish Total >108 Source: U.S. Congress. Office of Technology Assessment. Harmful Non-Indigenous Species in the United States. 1993. p. 92. Various original sources cited in report. Totals and percentages shown here are likely to be underestimated: entire groups of organisms (e.g., many categories of non-marine invertebrates) are not included; other studies show higher numbers of non-native plants, etc. See text for discussion. A Brief History of Introductions The first human introduction of a non-native species into North America is lost in antiquity. Nomads crossing the Bering Strait brought their dogs with them over 10,000 years ago. Polynesians landed in Hawaii bearing pigs, rats, and crop seeds over 1500 years ago. Nearly a thousand years ago, Icelandic settlers in what is now Greenland brought cattle, sheep, and goats with them (and perished with them, possibly due to a reliance on European livestock unable to find fodder in an increasingly harsh climate). Corn, native to Central America, was spread over much of North and South America well before 1492. In the 17th Century, Puritan colonists CRS-11 released domestic pigs into the New England forests to fend for themselves and provide food for the colonists. By the 1840s the descendants of the Puritan’s pigs were as common “as grains of sand on the sea-shore” in midwestern forests.17 The colonists also brought smallpox, measles, brucellosis, and other undesirables, to the severe detriment of native populations, both human and non-human. Some, like dandelions and Norway maples, have been in this country for so long that their nonnative status is remembered largely by specialists. According to the OTA report “[e]stimated numbers of [non-native species] in the United States increased over the past 100 years for all groups of organisms OTA examined.”18 Contributing factors include increases in the number of people traveling, the speed and methods of travel, trade generally, improved ability and speed in moving living plants and animals so that more of them survive the journey, the increase in modes of transport for hitch-hiking organisms (such as ship ballast water, pallet wood, and airplane wheel wells), the desire to have familiar sport and game animals in new areas, trade in horticultural and garden plants, trade in pets and aquarium animals, etc. Geographic Origins of Non-Native Species Plants and animals tend to survive best in a new site when that site is similar to their original habitat. Formosan termites arriving in New Orleans are much more likely to thrive than Formosan termites whose next stop is Anchorage, and a northern European grass seed traveling inside a prize bull is much more likely to survive in the Chicago area than the same species would in Miami. Thus, the plants and animals of northern Europe, Korea, northern China, Japan, and New England are more likely to be a threat to the stability of each other’s ecosystems, than any of them would be to the fauna and flora of Miami or Singapore. Regions with similar climates and soils around the world are tending toward increasing biological homogenization as plant and animal species spread and the new arrivals thrive at the expense of natives. This reverses the normal evolutionary pattern of ever-greater species divergence between two geographically separated regions — from biodiversity to “biosimilarity” — as the new arrivals create a homogenized flora and fauna in the two regions.19 17 C. Dickens, 1842, p. 165 in From Coastal Wilderness to Fruited Plain, by Gordon G. Whitney. (Cambridge, England: Cambridge University Press, 1994.) 18 19 OTA Report, p. 91. One author calls the phenomenon “evolution in reverse,” though this can be misleading, since species themselves do not return to previous evolutionary forms. Rather ecosystems become more similar, contrary to typically increasing divergence. See Christopher Bright, Life Out of Bounds: Bioinvasion in a Borderless World. New York, NY: W.W. Norton & Co, p. 17 (1998). (Hereafter referred to as “Bright.”) CRS-12 Near neighbors20 are less likely to be a source of pests. Canada, whose northern forests are contiguous with those of the United States, is not likely to be a source of forest pests, since its forests have no meaningful biological barrier separating them from our own. Consequently, if a native Canadian species could survive in a U.S. forest, it is probably already here. Similarly, desert plants of the southwest are probably shared with Mexico, and neither country’s native desert fauna or flora poses much of a threat to the other.21 Pathways of Invasion U.S. as Source of Non-Native Species While the focus of this report is on species that are not native the United States, this country is itself a source of species which threaten ecosystems elsewhere. The grey squirrel of the eastern and northern states was introduced to Britain, where it has severely threatened populations of the English red squirrel. In 1958, Pan Am Airways and a local hotel introduced largemouth bass into scenic Lake Atitlan in Guatemala. The introduction led, in the next 25 years, to the crash of a sustainable crab fishery and of several native fish, contributed to the near-elimination of the commercial harvest of reeds used in local handicrafts, and forced the extinction of a bird found nowhere else. Moreover, the harvest of the bass has since plummeted. And even at the ends of the earth, human fecal coliform bacteria contaminate McMurdo Sound, the major U.S. scientific research base in Antarctica. In an area thought of as earth’s most nearly pristine environment, the bacterium Clostridium perfringens contaminates over 80% of sea urchins near the undersea outfall of the untreated sewage from the base. The scientist who discovered this contamination plans to study the effect, if any, this sewage contamination is having on the plants and animals of the Sound. Analysts have identified no laws designed expressly to prevent the spread and proliferation of U.S. species in other countries, except in agricultural areas. To some extent, pathways of invasion between countries can be predicted. The arrival of zebra mussels and their attendant damage to city water supplies and electric utilities in the Great Lakes area focused much attention on the ballast water of cargo ships as a pathway for biotic invasion. Similarly, the propensity of brown tree snakes to hide in the wheel wells of airplanes has done much to focus attention on air stowaways. The recent arrival of Asian longhorned beetles may play a similar role in focusing attention on pallet wood, packing crates, live plants, and airport warehouses as pathways and centers of biotic invasion. In general, any arrival 20 “Near neighbors” must be construed biologically. For example, a spiderling dispersed by wind might easily be blown from British Columbia to Montana. A freshwater clam or a deep soil insect would scarcely ever be transported naturally from one to the other. 21 However, the statement does not apply to all ecosystems. For example, the higher elevation forests of the Sierra Madre in Mexico have been separated for millennia by hundreds of miles of desert from ecologically very similar forests of the Rockies. Pests, both plant and animal, could evolve in comparative isolation in these two areas, and be transported only recently with greater links of trade and traffic. Thus, the flora and fauna of either disconnected area could pose a threat to the other while the more continuously connected desert species are much less likely to do so. Moreover, non-native species may have invaded one area successfully without yet being found in the other; intervening desert could provide protection from invasion. CRS-13 of living or untreated material (water, wood, soil, etc.) should not be overlooked as a possible pathway for biotic invasion. A comprehensive review of possible pathways, their risks, options for control, and research needs is, to the authors’ knowledge, currently lacking. Within countries, certain paths for species invasions are quite predictable. In the 19th Century, the railroads over which cattle were transported were a major path for the establishment of new plants. In the 20th Century, the zebra mussel quickly escaped the drainage of the Great Lakes (probably via the artificial connection to the Illinois River), and began its invasion farther and farther south into the Mississippi River drainage. In addition to the accidental introduction of non-native species, introductions may occur from species deliberately brought into the country. In some cases, the importer does not intend for the imported plant or animal to escape to the wild, and in other cases, the purpose of importation is to promote its spread into natural habitats to achieve some desirable goal. In the first category are the imports of nonnative pets and plants. The importer is hardly ever interested in seeing the imported organisms escape. But once the specimens are sold, control is lost, and purchasers sometimes release unwanted non-native fish from aquaria or garden ponds, for example, into local lakes or streams, often feeling they are doing a humane thing by letting the fish go.22 A garden or greenhouse plant imported for horticulture may scatter shoots or seeds far more widely than expected. Water hyacinths, for example, were brought from South America in the late 19th Century as pool ornaments. The plant now covers thousands of acres in the southern United States, plus parts of Cape Cod and California, as well as parts of Africa and Asia. Moreover, the non-native animal or plant may harbor microorganisms that pose a danger to other species, even if the animal or plant itself does not survive in the wild. People deliberately release organisms into the wild for a variety of purposes. Several species of fish were deliberately released into the Colorado River for sport anglers. (The continuing presence of these fish has been one complicating factor in efforts to recover threatened and endangered species in and along the river, as well as to manage the river more naturally.) Salt cedar (or tamarisk) was introduced from Central Asia into the desert Southwest in the early 19th Century, in part to control erosion along river banks. The tree now forms dense thickets on more than a million acres of riparian habitat. The thickets have generally little value for most native 22 According to one author, “By far the most ecologically disruptive sector of the pet industry is the aquarium trade... Of those exotic fish species established in the United States that are completely foreign to the country, about 65 percent arrived through the aquarium trade.” (Bright, p. 162-163.). In contrast, the introduction of snakeheads (an Asian fish) began when they arrived alive to be sold in a New York City fish market. Two live fish were purchased and taken to Maryland where the buyer eventually decided not to cook them and so put them in an aquarium. When the fish got too big he released them into a nearby pond. They bred and their presence was discovered over a year later. See Snakeheads, below. CRS-14 animals, and the trees are estimated to absorb more water each year than all the cities of southern California.23 Basic Methods of Pest Prevention and Control The critical first line of defense against harmful non-native species is prevention of introductions, since success in controlling these species, once established, has been poor. Prevention is desirable from an ecological standpoint, and is usually economically advantageous, as most established non-native species cannot be eradicated, and controlling them to acceptable levels, when or if possible, is usually expensive. Because many deliberate releases of non-native organisms have not been wellplanned and have not taken into account the potentially injurious nature of the exotic species, nor compared the potential risks with expected gains, some organizations have developed guidelines and codes of practice. The American Fisheries Society,24 the International Council for the Exploration of the Sea, the World Resources Institute,25 and the Food and Agriculture Organization of the United Nations26 have prepared such guidelines to assist regulatory bodies and other groups in determining whether an introduction is justified, and then to advise them on what to do after an introduction is approved. These guidelines complement legislation described later in this report by providing a conceptual framework for determining whether the risk of introduction is acceptable, and then suggesting quarantine, monitoring, and/or adaptive management if an introduction is approved. Components of these guidelines have been incorporated in national legislation in the United States and elsewhere. Inspections and quarantines are key components of prevention by which the entry of non-native species via specific pathways might be controlled. This approach requires that species recognized as pests be listed and thus prohibited from entry.27 Quarantines operate basically on either of two premises: (1) invest in strict control at points of entry (by which time, it could be too late to prevent entry) or (2) attempt to control what arrives (i.e., try to act on the source or point of export or regulate the pathway of import). Ballast water management for ocean vessels is a means of “quarantine” whereby a major pathway of potential import for aquatic species is managed. A quarantine may also be posted on an area where a non-native species has been introduced, to prevent its further spread and promote its eradication. 23 Bright, p. 149. 24 [http://www.fisheries.org/Public_Affairs/Policy_Statements/ps_15a.shtml] on October 24, 2002. 25 [http://www.wri.org/biodiv/b12-gbs.html#guidelines] on October 24, 2002. 26 Devin M. Bartley, R.P. Subasinghe, and D. Coates, Framework for the Responsible Use of Introduced Species, EIFAC/XIX/96/inf. 8. Report of the 19th Session (Dublin, Ireland: European Inland Fisheries Advisory Commission, 1996). 27 For an overview of plant quarantine procedures and guidelines, see Robert P. Kahn, Plant Protection and Quarantine. Vol. 1 Biological Concepts (Boca Raton, FL: CRC Press, Inc., 1989), 226 p. CRS-15 Inspections and quarantines for agricultural pests are a major responsibility of the Animal and Plant Health Inspection Service (APHIS) of the U.S. Department of Agriculture (USDA). In addition, various states (particularly California, Arizona, and Florida) and territories conduct their own inspection programs aimed at agricultural pests. However, inspections and quarantines may not be effective for many species, especially non-target “hitchhiking” species, species which enter via uncontrolled or unrecognized pathways, and species that have invasive potential but are not yet recognized as pests. Public education also plays a critical role in preventing the introduction of harmful non-native species. Campaigns have been relatively effective in educating the public about the hazards of bringing non-native plant species home from vacation, or releasing undesirable exotic pets or aquaria life into the wild.28 Agriculture extension offices and the mass media are two generally effective means for distributing popular information to the public. In addition, the importance of educating specific groups, such as dock workers and vessel crew members, about controlling harmful non-native species could be emphasized, and might be integrated when possible with regulatory measures. If exclusion and quarantines fail to keep a non-native species out of an area, and a species becomes established, the problem shifts to control of the pest, which includes preventing its spread between local areas and beyond any established perimeter. Control of harmful non-native species is divided into two related tasks: eradication where possible, and reduction to manageable/tolerable levels29 where eradication is not possible. No single method of control is likely to be a panacea. Few control methods, if any, promise eradication under conditions where a species is well-established, but several methods, especially when used in combination and continuously, might reduce some target species’ populations to tolerable levels.30 Eradicating very small populations before they become established may be possible and is more likely if many methods are used intensively and in combination, including treating outlying populations as soon as they are discovered. For introduced species, control methods include at least nine basic categories: (1) baits and attractants; (2) traps; (3) fumigants, repellents, and barriers designed for confined spaces; (4) herbicides and pesticides (conventional and biological); (5) biological control; (6) bounties and commercial exploitation; (7) cultivation control; (8) mechanical removal; and (9) site removal. To apply any of these basic strategies of control, substantial knowledge of the target species’ behavior, biochemistry, dietary preferences, diseases, or other aspects of its biology is essential. The degree of species specificity of the selected approach can be a valuable asset in targeting control efforts. A number of species (e.g., the brown tree snake and the 28 The extensive national public education program using “Smokey Bear” very effectively communicated the role that private individuals could play in preventing forest fires; Smokey’s success may offer a model for preventing invasions of non-native species. 29 Identification of what might constitute such a manageable/tolerable level is subjective, value-laden, and open to interpretation, depending upon who is affected. 30 In the absence of eradication, control practices strive to be permanent, because residual pest populations could otherwise reproduce and return to problem levels. CRS-16 Mediterranean fruit fly) have been the focus of several of these strategies. In addition, control program managers should be expected to solicit public input early in the process of formulating and evaluating control alternatives and to answer questions from the public about possible human health, economic, and other effects from control programs. The pros and cons of these nine strategies, and some of the information needed to apply them, are described below.31 Comparatively more discussion is provided on biological control methods as they can sometimes involve the introduction of additional non-native species. Baits and Attractants. Baits and attractants may be used to draw unsuspecting individuals of a target species toward a potential source of food or mates (see the additional discussion below on pheromones under “herbicides and pesticides (biological)”), where the target species can be counted, trapped, killed, or studied. Difficulties with baits and attractants commonly include sustaining a longterm monitoring effort and preventing harm to non-target species. Baits and attractants seem most promising when the area needing protection is well-defined with clear boundaries and has a significant density of the target species. Traps. Trap use is limited primarily by cost, time required to service traps, and inability of traps to control target species over large areas. Various trap designs are available, and most are used in combination with some type of bait. For confined areas such as cargo holds, buildings, etc., traps may be relatively successful. On the other hand, traps have obvious drawbacks in open situations with either abundant alternative food or very low target species densities. Traps are comparatively safe to use, although they require some care when trapped individuals are killed and removed. Sticky traps have been used on rodents and brown tree snakes. Chinese mitten crabs have been trapped at irrigation screens during their downstream migration to spawn in saltwater. Fumigants, Repellents, and Barriers Designed for Confined Spaces. Lethal substances can be used to target pests in confined areas or to prevent them from crossing a geographic bottleneck. These methods can be used either to create pest-free “islands” in a zone of infestation or to prevent invasive species from leaving an infested area via boxes, cargo holds, etc. Some species are known to avoid certain substances, such as tear gas or gasoline. Obviously, these substances can be used only to a limited extent in areas where there is infrequent human access, rather than in area-wide application. Fumigants can also be used to kill or exclude pests from confined areas, such as cargo containers. For example, the Environmental Protection Agency has approved methyl bromide32 as a fumigant for the brown tree snake. Light is also known to repel some nocturnal animals. Submerged surfaces have been electrified at water and power facilities to discourage the settling of zebra mussel larvae and on ship hulls to inhibit barnacle settlement. Physical barriers can be used to prevent range extensions and access to new habitats, such as the electrical barrier 31 The discussion below draws heavily on U.S. Dept. of the Interior, The Brown Tree Snake, Boiga irregularis, A Threat to Pacific Islands, Biological Report 88(31), (Washington, DC: Fish and Wildlife Service, September 1988), p. 18-20. 32 For more information, see CRS Report 98-590 STM, Methyl Bromide and Stratospheric Ozone Depletion Policy Issues. CRS-17 being constructed by the Army Corps of Engineers in the Chicago Sanitary and Ship Canal to prevent or reduce the dispersal of invasive aquatic species between the Great Lakes-Saint Lawrence drainage and the Mississippi River drainage. Screens are used to prevent the movement of aquatic plant fragments within waterways. However, care is required to ensure that barriers do not impede the migratory behavior or natural dispersal of native species. Herbicides and Pesticides. These chemical control agents can be subdivided into those derived from manufactured (conventional) or natural (biological) sources. Conventional. Where chemical control is an option, herbicides and pesticides affecting or controlling only one or a group of related species are strongly preferable since broadly toxic substances risk substantial harm to non-target species. For example, TFM (3-trifluoromethyl-4- nitrophenol) is very specific in its toxicity to the larval stage of lamprey. Similarly, a variety of aquatic herbicides can be used specifically for the control of Hydrilla and water hyacinth. However, even if pesticides are highly specific, safety precautions often suggest the use of chemical control in conjunction with baits, thereby further reducing risks to pets, children, and other non-target organisms. Biological. Biological herbicides and pesticides (also known as biopesticides) are derived from natural materials, such as animals, plants, bacteria, and certain minerals. At the end of 2001, there were approximately 195 registered biopesticide active ingredients and 780 products.33 Biopesticides can be divided into three major classes: (1) biochemical pesticides are naturally occurring substances (e.g., pheromones) that control pests by non-toxic mechanisms (e.g., interfering with mating);34 (2) microbial pesticides contain a microorganism (e.g., a bacterium, fungus, virus, or protozoan) as the active ingredient, such as various types of the bacterium Bacillus thuringiensis (Bt) used to control certain insects harmful to cabbages, potatoes, and other crops;35 and (3) plant-incorporated protectants are pesticides that plants produce from genetic material that has been added to the plant, such as when the gene for the Bt pesticidal protein is introduced into a plant’s own genetic material causing the plant to manufacture the substance that destroys pests.36 Although biopesticides tend to pose fewer risks than conventional pesticides (they 33 [http://www.epa.gov/pesticides/biopesticides/what_are_biopesticides.htm] on October 24, 2002. 34 In some species (particularly insects), chemicals known as “sex pheromones” are given off that allow males and females to find each other. Sex pheromones work even when target species densities are low, and they are highly species-specific. For example, “Disparlure” (the commercially synthesized sex pheromone of the female gypsy moth) is used to trap male gypsy moths. Because it is sometimes difficult to determine whether a natural pesticide controls a pest by non-toxic means, EPA has established a committee to determine whether a pesticide meets the criteria for consideration as a biochemical pesticide. 35 Public concern has arisen over the use of Bt in some situations (e.g., for controlling Asian gypsy moths) because of possible adverse health effects that may occur in people with compromised immune systems. 36 Both the protein and its genetic material are regulated by EPA; the plant itself is not regulated. CRS-18 tend to be less toxic, usually are effective in very small quantities, often decompose quickly, and generally affect only the target pest and closely related organisms), users need to know a great deal about managing pests to employ them effectively. Biological Control. A biological control organism competes with, preys on, parasitizes, or causes disease in a targeted pest species. Ideally, biological control agents attack the target species and no others.37 Considerable knowledge of both the target species’ and the control organism’s basic biology and ecology is necessary to select a suitable control. Screening requirements vary for selecting biological control agents, with very stringent requirements for some uses, while requirements for other uses may be nonexistent. Together, individual state laws and APHIS (through 7 CFR 371) regulate the introduction of biological control organisms, and the USDA, through the Agricultural Research Service, administers a Biological Control Documentation Program. A particular concern with biological control organisms is that they might commence feeding on non-target species once target species are sparse or eradicated. An example of this problem is mongoose introductions. In the 1600s, mongooses were introduced in Puerto Rico to eradicate rats, which they did with great success. Unfortunately, mongooses proliferated and began to eat a variety of birds and other native animals. Similarly, the house sparrow (Passer domesticus, or English sparrow) was brought from Europe to control the canker worm. This non-native bird now crowds out native birds and damages crops. In recognition of these problems, vertebrate animals with broad feeding habits are seldom, if ever, used today as biological control agents. Production and release of large numbers of sterilized males has been particularly successful in controlling various insect pests (e.g., medflies, screwworm flies, Cochliomyia hominivorax) and sea lamprey. Competitive mating by sterilized males results in lower reproductive rates for the invasive species population, reducing its abundance and potentially controlling population spread. Using a disease or selective parasite may be an attractive option in some circumstances, but again there is a risk that the disease or parasite will attack nontarget species. Fieldwork in a target species’ native habitat is usually necessary to identify diseases or parasites to which the target species may be susceptible. Although the requisite research might be expensive, using biological control agents holds hope for long-term control. The alligator weed flea beetle (Agasicles hygrophila) for control of alligator weed (Alternanthera philoxeroides) and the current program using several beetles (Galerucella pusilla, G. calmariensis, and Hylobius transversovitattus) to control purple loosestrife are success stories for biological control of plants. The brown tree snake of Guam could be a possible candidate for biological control, since there is only one snake native to Guam and its habitat is quite different from the brown tree snake’s. Thus, the chance of an introduced parasite or disease affecting the native snake species is minimal. 37 The USDA requires proof of host-specificity before supporting an insect introduction for non-native plant control. CRS-19 Natural biological control can also occur through adaptive ecosystem response by native species to invasive species. An example is the indigenous weevil, Euhrychiopsis lecontei, which is a specialist feeder on northern water milfoil (Myriophyllum sibiricum). Once this weevil is exposed to the non-native Eurasian water milfoil (M. spicatum), it appears to change its feeding habits to preferentially feed upon the Eurasian variety. In Oregon, the native defoliating butterfly, Vanessa cardui, feeds on introduced thistles, Cirsium arvense and C. vulgare. Other forms for biological control may involve planting competitive vegetation and managing livestock grazing. For example, grazing by sheep and goats can be an effective management tool for controlling leafy spurge. Bounties and Commercial Exploitation. Under a bounty system, someone is paid to catch and kill the target species. High bounties may have to be paid to encourage sufficient control that results in a substantial effect on the target species’ population. The problem, however, is that paying bounties can create a market incentive — a particular risk when a population dwindles to very low levels and prices go up or bounties are increased. In addition, these methods may have incidental adverse ecological consequences for native species arising from increased human traffic and collecting methods. In August 1999, the California Department of Fish and Game decided against permitting the commercial harvest of non-native Chinese mitten crabs, concluding that such harvest would not contribute to controlling this species and might encourage further introductions. Cultivation Control. Use of such measures as timing of fertilizer applications, adjustment of planting dates, and crop rotation can be valuable management and control tools for invasive weeds. Some cultivation control methods, while minimal in cost and equipment, may require an additional commitment of labor and are unlikely to be effective unless combined with other control methods. Mechanical Removal. Mechanical controls may be used to collect and remove large volumes of invasive non-native species, particularly plants. Mechanical harvesters may be used in the management of non-native aquatic vegetation, such as Hydrilla and water hyacinth, but are ineffective for control of these species on large bodies of water. Mechanical controls are also used to prevent the further spreading of established non-native species, and include methods such as cleaning of equipment (e.g., during highway construction) and using certified weed-free seed and feed (e.g., weed seeds have been mechanically excluded or removed). Mechanical control of terrestrial plants includes such basic procedures as hand-pulling and mowing. Some of these methods may require expensive specialized equipment or substantial commitment of labor to be effective. Site Removal. The recently introduced Asian longhorned beetle (still perhaps at low enough levels to have some slight chance of being eradicated) is currently being controlled to some degree by removing all trees on which the pests might feed in neighborhoods where they have been found. Site removal has also been used in California to eradicate Hydrilla by draining small ponds and filling their depressions with earth. Such a drastic strategy would be unworkable if a pest becomes widely dispersed. CRS-20 Unusually Susceptible Habitats Harmful non-native species occur throughout the United States, but some ecosystems are more susceptible to invasion than others. Mild climate, geographic isolation, disturbance of the natural landscape,38 and a high rate of exposure to nonnative species are all factors which can make a habitat particularly susceptible to invasion. Islands and other long-isolated areas with unique plants and animals are also known to be particularly susceptible to invasive species. Hawaii and Florida, for example, each have many threatened and endangered species and, not coincidentally, a plethora of harmful non-natives. Both states were long isolated biologically and have large numbers of native species found nowhere else. The mild climates of Florida and Hawaii make it easier for the rich flora and fauna from the rest of the tropical and semitropical regions to survive, and also make the states attractive to businesses that import and maintain or even breed non-native animals and plants, such as tropical fishes and ornamental plants. In Florida, the number of non-natives seemed overwhelming to a local reporter: In southern Florida, especially, untrammeled whims of humans have introduced so many species of non-farm animals (mainly as “pets”) that the native fauna is greatly diluted. Running wild in Dade and Broward Counties have been piranhas, walking catfish, blue tilapia (“introduced from Africa in 1961 by officials of the Game and Freshwater Fish Commission”), electric eels, little barbed Amazonian catfish that swim up [human] urinary tracts, and other fish (“23 exotic fish now breeding in the wild”), Cuban anoles, iguanas, Asian water monitors, caimans, boa constrictors, pythons, mambas (“people want the newest animals as pets”), red-whiskered bulbuls, monk parakeets, howler monkeys, gibbons, green African savannah monkeys, crab-eating macaques, and a herd of 300 buffalo.39 Both Hawaii and Florida are major travel destinations and transportation hubs, so they are more likely to be subjected to inadvertent introductions. In both states, large areas have been cleared of native plants. It is often easier for non-native species to establish themselves in such disturbed habitats — in fact, many invasive species are weeds that have evolved to exploit such land and then “hitchhike” to freshly disturbed areas. Another factor putting some environments at risk is the sheer number of opportunities for new introductions. Seaports, in which ships have exchanged ballast 38 Some writers argue that evidence is lacking on how disturbance affects susceptibility to invasions. But scientists generally accept the idea that severe depletion of an ecosystem’s flora and fauna (e.g., through fire, storm, volcanic eruption, etc.) does offer significant opportunities for newly arrived species, since the new arrivals face reduced competition in disturbed habitat. 39 W. Belleville. “Critter patrol,” Florida (a news magazine of the Orlando Sentinel Star), 29 May 1994: 8-12, 15. Some of this paragraph may reflect the reporter’s view of the subject more than a strict interpretation of fact. For example, not all of the species mentioned actually reproduce in south Florida. In focusing only on exotic pets however, the paragraph understates Florida’s problem. CRS-21 water daily for decades or even centuries are at severe risk of invasions. Even if only a tiny proportion of newly arriving non-native species survive in the new habitat of San Francisco Bay, Chesapeake Bay, or Boston Harbor, the actual number of successful, invasive species may be very large. The areas around airports, with increasing volumes of international traffic and tourism, are also at risk. In addition, the greater the similarity of the point of origin, the more likely the invasion is to be successful. For example, biotic invasion of the Hawaiian islands is more likely to come from a plane originating in Guam than one originating in Anchorage. Available Estimates of Costs and Impacts It is difficult to quantify the damage due to invasive species. One study by Pimentel and his colleagues put annual costs and damage due to non-native species at $123 billion per year.40 The study included no information about the overall costs of excluding non-natives. The assumptions used in the study to make these estimates may be questioned as over- or understating the costs; probably no two scientists or economists would make the same assumptions to derive such an estimate. As one of the first attempts to make a broad estimate over a very large range of species, the figure of $123 billion should be construed an informed estimate, and the interested reader should examine the report itself to assess the validity of the assumptions used to derive the figures. The handful of species highlighted in this report alone cause annual losses over $3.5 billion, and two (Formosan termite and Asian river clam) are responsible for $1 billion each in control costs, diminished property values, and other damage. Even if new imports of non-natives were completely halted (a near impossibility), the costs of controlling established non-native species would continue. The value and the cost of prevention are difficult to assess. In the absence of any other information, since the first several thousand harmful non-native species (i.e., those for which any numbers could be gathered) collectively were estimated to cause about $123 billion annually in costs and damage, it seems reasonable to assume that the next several thousand to arrive and become established could cause comparable economic damage. Damage could include the same types of damage already known to affect economies and ecosystems through power outages; changes in flood regimes; increased erosion; loss of farmland property value; contamination of grain; spread of disease; increased operating costs; inefficient irrigation; higher risk of fire; collapse of buildings; loss of sport, game, or endangered species; ecosystem disturbance; etc.. There could also be effects on industries or ecosystems that have not yet been markedly harmed by non-natives (e.g., the threat to fall tourism and the maple syrup industry in New England from Asian longhorned beetles, which attack and kill a variety of tree species, but are particularly fond of maple trees and their relatives). Targeting each newly arriving non-native species individually seems very likely to be more costly than targeting pathways or groups of species. A focus on high-risk pathways could be more cost-effective over the long term, but a pathways approach 40 Pimentel report, p. 1. CRS-22 itself has costs, as evinced by debate over the arrival of the Asian longhorned beetle. In an effort to stop or slow the entry of this widespread Asian species, controls were placed on its suspected major pathway — raw wood packing material of imports from China (rather than from all the Asian countries in which this species is common) and, for a time, the controls threatened a trade war with China. It also escalated federal government attention to the problem of non-natives to the highest levels of government. (See Asian Longhorned Beetle, below.) Another cost of biological invasion is restoration of disturbed habitat, if it is undertaken at all. Damage due to an invasive species tends to rise as the species becomes established. Education of the public (which may stop the transport of many species before it even starts) can be relatively inexpensive on a per species basis. At each subsequent stage — transport, release, establishment, and spread — the cost of eradicating the non-native typically increases. And once the species is established over a wide area, eradication could be virtually impossible for any reasonably foreseeable sum. If a non-native becomes established and some local (and necessarily continuing) control occurs, restoration of the damaged habitat might be attempted, insofar as possible. Restoration could involve recruiting small armies of volunteers to pull non-native plants, hiring sharpshooters or trappers to kill or capture animals, transporting animals to native habitat, dredging streams and lakes, poisoning lakes, etc. Many restoration efforts could involve not only major costs but also substantial political controversy.41 The controversy illustrates the dilemma for policymakers. Specifically, the high cost to many industries (even seemingly unlikely ones, such as imported computer parts, steel, or other products with no obvious connection to living organisms), to economic interests, and to ecosystems from unwanted species is balanced against the costs of protective measures imposed on commerce in general. It will also have to be balanced against the needs of domestic industries (horticulture, agriculture, pet trade, etc.) that depend directly on importing non-natives. 41 The manager of one national wildlife refuge (in Hawaii) told one of the CRS authors that no control efforts at all would be attempted at that time in one distant area of the refuge that was overrun with non-native species, since only very substantial budget and time commitments would produce results, and any effort short of that would be a waste of money. Failing that, control efforts were instead directed to other areas with greater chances of success within available budgets. Restoration costs at that refuge might therefore be considered either zero — or completely insurmountable. CRS-23 Industries That Benefit from Non-native Species While the ecological damage from some non-native species can be great, only a small percentage of arrivals have proved to be economically harmful, and many are beneficial.42 (For many species, the economic impacts are simply unknown.) Some industries rely heavily on non-natives. For example, nearly all food plants and animals in the United States are not native to the areas where they are now grown. Besides agriculture, industries relying significantly on non-native species include the nursery, aquaculture, and pet industries. Most woody invasive plants in the United States were originally introduced by the landscape industry.43 The giant hogweed, whose toxic sap can cause severe scarring, was introduced as an ornamental but escaped cultivation and is now widely listed as a noxious weed.44 Similarly, water hyacinths were introduced, apparently as an ornamental for garden ponds. (See Gallery, below.) As a result of this and similar escapes, the nursery industry has been subjected to increasing criticism. States are increasing their regulation of potentially invasive species.45 Some of those species are economically important to the nursery industry. Some industry groups have been working to develop voluntary controls to lessen the risk of inadvertent introduction of invasive plants. Production from private aquaculture nearly tripled from 1985 to 1999 and was worth more than $987 million in 1999.46 Many cultured species are not native. There is concern about the escape and establishment of cultivated species that may be harmful to native ones. Examples include the threat of Atlantic salmon in the Pacific Northwest; and the inadvertent introduction of diseases, such as dermo and MSX in oysters; or of other pest species. Concerns are similar for the aquarium and exotic pet trades, which rely heavily on tropical species. The United States is the world’s leading importer of reptiles, for example, and though the chief concern has been for potential effects on source countries (e.g., iguanas from Central America), there are concerns regarding possible escapes, especially in southern states.47 A number of the species (some described in the Gallery below) were thought or known 42 Only a few commercial foods now grown in the U.S. are apparently native to this country. Known examples include sunflowers, Jerusalem artichokes, pecans, black walnuts, some wild cherries, strawberries, blueberries, and cranberries. Other familiar foods of the new world (e.g., corn, potatoes, chilies, and tomatoes) either were not grown in this country in 1492, or were non-natives brought in earlier by Native Americans. For some foods, the native range is still debated. 43 S.H. Reichard and C.W. Hamilton, “Predicting Invasions of Woody Plants Introduced into North America,” Conservation Biology, vol. 11 (1997):193-203. 44 Mary Robson, “The Perils of Giant Hogweed,” [http://gardening.wsu.edu/column/07-05-98.htm], 5 July 1998. 45 FICMNEW report, p. 86-91. 46 U.S. Joint Subcommittee on Aquaculture, “U.S. Private Aquaculture Production for 1985-1999,” October 2001. [http://ag.ansc.purdue.edu/aquanic/jsa/aquaprod.htm] 47 Data from Traffic International [http://www.traffic.org/dispatches/archives/september98/], established to assist in the implementation of the Convention on International Trade in Endangered Species. CRS-24 to have entered the United States as pets, or in association with pets: caulerpa, hydrilla, apple snails, goldfish, walking catfish, budgerigars, ring-necked doves, and common pigeons.48 Harm to the Natural Environment: Diffuse Responsibilities Responsibilities for native flora and fauna and the ecosystems in which they live are scattered — the wards of many or of none. Generalized effects on ecosystems from very large to very small (e.g., the Great Lakes, suburban trees, Texas lawns) are not the specific responsibility of one federal agency. With so many pathways for the entry of non-natives, so many possible entering species, and so many possible and nearly unknowable injured species, the natural ecosystem as a whole has no specific guardian. This scattered responsibility is a result of the evolving legal history of species protection,49 agriculture, and import regulation. U.S. law concerning native wild plants and animals is not a comprehensive body at the federal level. Under our system, inherited from English legal tradition, and stated very simply, the government regulates the “take” of native wild animals generally, and landowners control the native (and other) plants growing on their lands. A wild deer walking across a pasture does not “belong” to the landowner but is rather the government’s to regulate; the bush it eats belongs to the landowner. Thus, colonial governments regulated native wild animals and, after the U.S. Constitution was ratified, the states retained the rights they previously had as colonies to control the wildlife within their boundaries. Aside from special rules for lands owned by the federal government, federal native wildlife law can be thought of as a series of exceptions to the general concept that states regulate wild animals, and landowners manage (or don’t manage) wild plants. Some of the major exceptions to that generalization include federal laws regulating the taking of migratory birds (pursuant to treaties), marine mammals, and endangered species. The great majority of native wild plant and animal species do not fall into any of these categories and therefore are not direct federal responsibilities under current law. Native wild flora and fauna are frequently protected as a consequence of protecting something else — agriculture and endangered species, for example. Where there have been specific injuries to other industries or interests (utility intakes, for example). the pathway by which the harmful species arrived may be regulated to prevent other non-natives arriving via that pathway. Natural ecosystems, as result of the threats to other interests, may benefit from an incidental reduced risk of harm arriving by a pathway that is controlled. 48 For an overview of the risks of both plants and animals introduced from the aquarium trade, see [http://www.vetcentric.com/magazine/magazineArticle.cfm?ARTICLEID=1443]. 49 For a general discussion of early development of federal wildlife law, see The Evolution of National Wildlife Law, 3rd ed., by Michael J. Bean and Melanie J. Rowland (Westport, CT: Praeger Publishers. 1997), p. 7-14. CRS-25 Federal Laws Federal law concerning non-native species is scattered. No laws focus on the broad problems of non-native species, their interception, prevention, and control across a variety of industries and habitats. The body of law addressing non-native species and agriculture appears better-developed than laws relating to other sectors of the economy or the nation’s natural resources. Some laws, though they do not directly address non-native species control or prevention, have effects that may limit such introductions. Below is a brief digest of existing laws, presented in chronological order of enactment, which affect non-native species introduction, prevention, and control. However, control of non-native species is not the major purpose of the law in some cases included below. In addition to federal laws, a number of states have laws restricting transport or possession of non-native species. State laws are not described in this report. Also omitted are the handful of federal laws referring to single species. Lacey Act Originally enacted in 1900, the Lacey Act (16 U.S.C. 3371-3378, 18 U.S.C. 42) makes it illegal to import, export, sell, receive, acquire, or purchase fish, wildlife, or plants50 taken, possessed, transported, or sold in violation of U.S. or tribal law. In addition, this Act makes it unlawful to engage in interstate or foreign commerce involving any fish, wildlife, or plant material taken, possessed, transported or sold in violation of state or foreign law. Specific provisions authorize the federal government to prescribe requirements and issue permits for importing wild animals under humane and healthful conditions.51 One portion of the Act (18 U.S.C. 42) appears to give the Secretary of the Interior and the Secretary of the Treasury considerable power to exclude three major categories of non-native animals: vertebrates, crustaceans, and mollusks. Moreover, grounds for exclusion were expanded beyond the traditional harm to agriculture, horticulture, and forestry interests to include harm to “wildlife and wildlife resources.” The inclusion of the latter could mean that nearly any non-native member of these groups could be considered for exclusion, since most and perhaps all ecologists would hold that the proliferation of any non-native species in an ecosystem risks harm to its wildlife resources. The reach of the law is somewhat unclear, however. Is the Secretary of the Interior to prepare a “white list” or a “black list”? In the 1970s, the Interior Department interpreted the provision as permitting 50 Plants are commonly covered under somewhat different provisions than animals are. To be covered under the Lacey Act, plants must be “indigenous to any state” and either protected under the Convention on International Trade in Endangered Species or under a state law protecting species threatened with extinction. Thus, a state like Hawaii apparently could not use the Lacey Act to help enforce that state’s laws designed to keep out common native (mainland) plants. On the other hand, the Act might help the same state exclude animal pests from other states, whether native to the state of origin or not. 51 The term “wildlife” can have various meanings in federal and state laws, including game species; game species except fish; mammals (rather than birds); or the entire animal kingdom. CRS-26 a white list, and attempted to develop regulations accordingly. Public protest, chiefly from the pet industry but also others, stopped the process.52 Current regulations, which adopt a black list approach and name only a small number of species to be excluded, are found at 50 CFR Part 16. Animal Damage Control Act The Animal Damage Control Act of 1931, as amended, (7 U.S.C. 426 et seq.) is the primary statute under which APHIS operates its Wildlife Services (WS) program (known until 1997 as the Animal Damage Control program). The Act gives APHIS wide authority to control wildlife damage on federal, state, or private land. WS is involved in protecting: (1) field crops, vegetables, fruits, nuts, horticultural crops, and commercial forests; (2) freshwater aquaculture ponds and marine species cultivation areas; (3) livestock on public and private rangeland and in feedlots; (4) public and private buildings and facilities, such as houses, commercial properties, swimming pools, golf courses, reservoirs, levees, and landfills; (5) civilian and military aircraft (against collisions with birds); and (6) public health (against wildlifeborne diseases such as rabies, Lyme disease, West Nile virus, and plague). WS control methods include providing advice to individuals and to municipal, state or federal agencies on a wide variety of preventive, non-lethal control methods. Control of predatory animals, native or non-native, is largely carried out by lethal means, including hunting, trapping, and poisoning. WS also has cooperative agreements with the Fish and Wildlife Service (FWS), the National Park Service, the Bureau of Land Management, the Forest Service, and state natural resource agencies to help protect natural resources, including wildlife and threatened or endangered species, from loss of life, habitat, or food supply due to the activities of other species. Under the authority of the Act, as broadened by the Agricultural Appropriations Act of 2001 (P.L. 106-387), APHIS addresses damage problems caused by such non-native species as nutria, European starlings, and monk parakeets. Also in 1991, Congress passed P.L. 102-237, which (among other things) amended the Animal Damage Control Act specifically to add the brown tree snake to the list of animals that WS is charged to monitor and control. Federal Seed Act The Federal Seed Act of 1939, as amended (7 U.S.C. 1551 et seq.), requires accurate labeling and purity standards for seeds in commerce. Among other things, the Act prohibits importing and moving adulterated or misbranded seeds, and imposes labeling requirements. The Act also authorizes enforcement activities and rulemaking functions. In addition, this Act regulates interstate and foreign commerce in seeds, and addresses “noxious weed seeds” that may be present in agricultural 52 For a brief history of these actions, see Michael J. Bean and Melanie J. Rowland. The Evolution of National Wildlife Law, 3rd ed. (Westport, CT: Praeger Publishers, 1997), p. 53-55. These authors argue that the legislative history of the Act is unclear on the question of species-by-species lists. If white lists were permitted, the statute could be a powerful check on importing and transporting non-native animals in the three major taxonomic groups it covers. CRS-27 (e.g., lawn, pasture) or vegetable seed. APHIS administers the foreign commerce provision of this Act; the Agricultural Marketing Service administers the interstate commerce provisions. The law works in conjunction with Plant Protection Act to authorize APHIS to regulate only imports of agricultural seed that may contain noxious weed seeds. National Environmental Policy Act of 1970 (NEPA) NEPA (P.L. 91-190, as amended; 42 U.S.C. 4321, et seq.) requires, among other things, that federal agencies consider and consult with the public about the environmental effects of their actions. The primary mechanism to achieve this end is the preparation of environmental impact statements (EISs) for major federal actions affecting the environment. Agencies are expected not only to prepare EISs, but also to comment on the EISs prepared by other agencies.53 This law could apply to some introductions of non-native species. If a federal action might affect the risk of introducing or spreading non-native species, thereby having a significant impact on the natural and human environments, the associated EIS would have to address this possibility. The limitations of NEPA vis-a-vis its application to non-native species include: limited applicability to actions without a federal connection; inapplicability to completed federal actions, although these actions may have effects that continue into the present; ! limited utility if the possibility of introducing non-native species is not foreseen; and ! the inability of scientists to provide agency administrators with the information necessary to assess the risks or consequences associated with introducing most non-native species. ! ! If NEPA is invoked, the opportunity for significant analysis of a proposed action via an EIS is great. The resulting analysis may cause modification or abandonment of some actions or alternatives, if serious objections are raised. However, because NEPA is essentially procedural, it does not, by itself, prevent an activity, even if the risk of unfavorable environmental outcomes is high. Nonetheless, failure to consider the issue of non-native introductions could be grounds for requiring an agency to amend its EIS, thereby delaying the introduction and risk while the revision is prepared. 53 For an overview of NEPA, see CRS Report 97-49 ENR, Summaries of Environmental Laws Administered by the Environmental Protection Agency, p. 109-113. While the focus is on the responsibilities of that agency, the fundamentals of the Act are also explained. CRS-28 Endangered Species Act (ESA) The ESA54 (P.L. 93-205, as amended; 16 U.S.C. 1531-1543) focuses its attention on species that are rare, not those that are common to the point of being weeds or pests. However, the strong protections offered under the ESA for rare species may provide a vehicle for regulating non-native species. For example, in the Pacific Northwest, the threat to resident salmon species protected under ESA is a major argument being used against the introduction or expansion of aquaculture for Atlantic salmon. Similarly, introduction of mountain goats in an area where they are not native would be more likely to be questioned if there are local endangered or threatened plants likely to be harmed by the goats. ESA could provide protection in two ways. First, if the introduction were to be carried out by a federal agency or require licensing, financial support, permits, etc., from a federal agency, the agency involved would have to consult with FWS or National Marine Fisheries Service (NMFS) to determine whether the introduction (or action leading to introduction) would tend to jeopardize the continued existence of the listed species or adversely modify its critical habitat. If so, the introduction would usually be prevented or modified to reduce the risk. Second, if the action had no federal nexus, but its effects could result in taking (as defined in the Act) a listed species, the party carrying out the action would have to obtain an incidental take permit from FWS or NMFS. Questions of knowledge, intent, and causality affect whether violations under the ESA have occurred and whether penalties may be applied. Therefore, as a practical matter, ESA is an unlikely alternative for penalizing the introduction of non-native species because the persons responsible for introducing many non-native species may never be known and introduction is often inadvertent. For example, it is not known who introduced zebra mussels, and it is likely that their probable introduction via ballast water was unintentional. In addition, introductions may go unnoticed for a long time, compounding the difficulty in determining responsibility. For example, the introductions of the brown tree snake on Guam went unnoticed for years after their arrival, though the brown tree snake is strongly suspected of being directly responsible for the extinction of several species on Guam. Consequently, enforcement actions under ESA in the usual sense are unlikely. However, the policies of the ESA and the duty of federal agencies to ensure that federal actions will not jeopardize species listed under the Act may result in changes in certain practices and the tightening of regulation of potential pathways, e.g., greater regulation of ballast water practices or design requirements for aircraft cargo holds to reduce the chance of biological stowaways. Although there may be some circumstances in which the ESA will play a role, Congress may see new laws more directly and better suited to the prevention of introductions as also desirable. 54 For more information about the ESA generally, see CRS Issue Brief IB10072, Endangered Species: Difficult Choices. CRS-29 Federal Noxious Weed Act Although most provisions in the Federal Noxious Weed Act of 1974 (P.L. 93629) were supplanted by the Plant Protection Act (see below), a key section (7 U.S.C. §2814) still requires each federal agency to provide for noxious weed management on lands under its jurisdiction. The provision, introduced in the 1990 Farm Bill (P. L. 101-624, title XIV, §1453, 104 Stat. 3611) amended the Federal Noxious Weed Act to require federal agencies to establish and fund noxious weeds management programs through the agencies’ budgetary process. It also allowed the agencies to implement cooperative agreements with state agencies regarding the management of undesirable plant species in areas adjacent to federal lands. The Act requires joint leadership from the Secretaries of Agriculture and of the Interior in coordinating federal agency programs for control, research, and education associated with designated noxious weeds. In 1994, a memorandum of understanding among several federal agencies created the Federal Interagency Committee for Management of Noxious and Exotic Weeds (FICMNEW) as a vehicle to coordinate noxious weed priorities (see Interagency Efforts, below). Nonindigenous Aquatic Nuisance Prevention and Control Act The Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 (NANPCA; Title I of P.L. 101-646; 16 U.S.C. 4701, et seq.) established a federal program to prevent the introduction of, and to control the spread of, unintentionally introduced aquatic nuisance species and the brown tree snake. The Coast Guard, EPA, FWS, the Army Corps of Engineers, and the National Oceanic and Atmospheric Administration (NOAA) share responsibilities for implementing this effort, acting cooperatively as members of an Aquatic Nuisance Species (ANS) Task Force to develop a program for protection, monitoring, control, and research. The Task Force conducts studies and reports to Congress: (1) to identify areas where ballast water exchange can take place without causing environmental damage; (2) to assess whether aquatic nuisance species threaten the ecological characteristics and economic uses of U.S. waters other than the Great Lakes; (3) to determine the need for controls on vessels entering U.S. waters other than the Great Lakes; and (4) to identify and evaluate approaches for reducing the risk of adverse consequences associated with intentional introduction of aquatic organisms.55 Under NANPCA, state governors are authorized to submit (1) comprehensive management plans to the Task Force that identify areas or activities for which technical and financial assistance is needed; and (2) public facility management plans to the Assistant Secretary of the Army (Civil Works) that identify public facilities for which technical and financial assistance is needed. Grants are authorized to states for implementing approved management plans, with maximum federal shares of 75% 55 See [http://www.ANSTaskForce.gov/accomp.htm] for accomplishments of the ANS Task Force. CRS-30 of costs for each comprehensive management plan, and 50% for each public facility management plan.56 Under §1101 of NANPCA, a Great Lakes ballast water management program (voluntary in its first 2 years) became mandatory in 1992. This section directed the Coast Guard to issue regulations (33 CFR Part 151) to prevent the introduction and spread of aquatic nuisance species into the Great Lakes through the ballast water of vessels and established civil and criminal penalties for violating these regulations. The Act also encourages the Secretary of Transportation, through the International Maritime Organization, to negotiate with foreign countries on the prevention and control of the unintentional introduction of aquatic nuisance species. In addition, the Act directs the Corps of Engineers to develop a program of research and technology for the environmentally sound control of zebra mussels in and around public facilities, and make information available on these control methods. Subsequently, the Corps established a zebra mussel facility research program, including annual technical conferences and a publication series. National Invasive Species Act In 1996, the National Invasive Species Act (NISA; P.L. 104-332) amended NANPCA to create a national ballast management program modeled after the Great Lakes program wherein all ships entering U.S. waters (after operating outside the U.S. Exclusive Economic Zone) are directed to undertake high seas ballast exchange or alternative measures pre-approved by the Coast Guard as equally or more effective. While initially unenforced on a ship-by-ship basis, this national program was to have become mandatory within 3 years of the date the Coast Guard issued its voluntary guidelines57 if ships did not show adequate compliance with the program58 in the absence of enforcement. The National Ballast Information Clearinghouse (NBIC) was developed jointly by the Coast Guard and the Smithsonian Environmental Research Center to synthesize, analyze, and interpret national data concerning ballast water management. During the first 2 years (July 1999 through June 2001), the NBIC found that nationwide compliance with ballast exchange reporting requirements was low, with only 30.4% of vessels entering the U.S. Exclusive Economic Zone (EEZ) filing reports with the NBIC.59 On March 4, 2002, the Coast Guard published an advanced notice of proposed rulemaking, seeking comments on development of a ballast water treatment goal and an interim ballast 56 Despite substantial authorizations, relatively little has been appropriated or made available for state grants to implement these management plans. 57 64 Fed. Reg. 26672-26690, May 17, 1999. These regulations are effective July 1, 1999. 58 If the voluntary program does not result in sufficient compliance, reporting of ballast water management practices will become mandatory for nearly all vessels entering U.S. waters (33 CFR 151.2040). If necessary, the Coast Guard will promulgate further regulations to implement such a mandatory reporting program. 59 G. M. Ruiz, et al., Status and Trends of Ballast Water Management in the United States: First Biennial Report of the National Ballast Information Clearinghouse, (Edgewater, MD: Smithsonian Environmental Research Center, Nov. 16, 2001), p. 4. CRS-31 water treatment standard as part of regulations that would make guidelines for ballast exchange mandatory.60 NISA encouraged negotiations with foreign governments to develop and implement an international program for preventing the introduction and spread of invasive species in ballast water. This Act required a Coast Guard study and report to the Congress on the effectiveness of existing shoreside ballast water facilities used by crude oil tankers in the coastal trade off Alaska, as well as studies of Lake Champlain, the Chesapeake Bay, San Francisco Bay, Honolulu Harbor, the Columbia River system, and other estuaries and waters of national significance. It also authorized funding for research on aquatic nuisance species prevention and control in the Chesapeake Bay, Gulf of Mexico, Pacific Coast, Atlantic Coast, and San Francisco Bay-Delta Estuary. Under NISA, a Ballast Water Management Demonstration Program was established to promote the research and development of technological alternatives to ballast water exchange. In addition, NISA modified the composition and research priorities of the Aquatic Nuisance Species Task Force; and expanded the zebra mussel demonstration program requirements. Research grants were required on environmentally sound methods for controlling the dispersal of aquatic nuisance species. In addition, the Corps of Engineers was directed to investigate and report to Congress on methods specifically for preventing and reducing the dispersal of species from the Great Lakes-Saint Lawrence drainage into the Mississippi River drainage through the Chicago River Ship and Sanitary Canal. In addition, research was authorized on the prevention, monitoring, and control of aquatic nuisance species in Narragansett Bay, Rhode Island. Finally, NISA required the Task Force to develop and implement a comprehensive program to control the brown tree snake in Guam and other areas where the species has spread outside of its historic range. NISA has been criticized as inadequate and faulted for several alleged shortcomings, including weakness in implementing some of its provisions.61 Since NISA exempted most coastwise vessel traffic from ballast water exchange guidelines, vessels traveling short distances (e.g., from San Francisco Bay, which is highly invaded, to Puget Sound, which is less so), and therefore likely to be carrying live organisms, are exempt from controls. With the exception of the Great Lakes, critics point out that no ecological surveys or management actions have been funded for inland waters such as the Colorado, Rio Grande, or Missouri Rivers. In addition, they claim that sections of NISA pertaining to invasive plant management have not been funded or used. Others are critical of the provisions of 16 U.S.C. 4711(k)(2)(A) giving the vessel owner a blanket exemption to ignore any mandatory regulations if the master determines that the vessel might not be able to safely conduct a ballast water exchange on the open ocean. Whereas earlier provisions applicable to the 60 61 67 Fed. Reg. 9632-9638. Letter of February 11, 1999, to Hon. Carol Browner, Administrator of Environmental Protection Agency, from Representatives George Miller, Jim Saxton, and 16 other Members of the U.S. House of Representatives. CRS-32 Great Lakes provided a safety exemption, the master of a vessel was required to report the problem to the Coast Guard and conduct alternate ballast water management measures, often negotiated on a case-by-case basis. Critics believe the NISA language has eliminated any incentive to change ballast water piping systems or adopt other management or treatment options to deal with the problem safely. Alien Species Prevention and Enforcement Act of 1992 (ASPEA) This law (P.L. 102-393; 39 U.S.C. 3015) makes it illegal to ship certain categories of plants and animals through the mail. The prohibited species are those injurious animals whose movement is prohibited under part of 18 U.S.C. 42 and those plants and animals whose shipment is prohibited under 16 U.S.C. 3372. (Both sections are part of the Lacey Act.) ASPEA does not make any new categories of plants or animals illegal to ship, but rather makes it clear that use of the U.S. mail is included among those forms of transport whose use is illegal for shipment of prohibited species. PEA appears to do very little to prevent the introduction of non-native species, especially if the sender is unaware that the shipped items are prohibited under the above laws, but ASPEA does appear to add one more law to the arsenal under which prosecutors might bring cases involving shipment of various species, including non-native species, to court. Wild Bird Conservation Act of 1992 (WBCA) The WBCA (P.L. 102-440; 16 U.S.C. 4901, et seq.) does not focus on the prevention of invasions by non-native species, but rather on the conservation of birds caught in the wild in foreign countries and imported into this country. By regulating imports of certain wild birds, the WBCA may reduce imports of non-native parasites and diseases that could affect wild populations of native birds. Prevention of invasions would therefore be a potential effect of the law, rather than its purpose. It also could reduce the chance that an imported wild bird species could escape, breed, and increase to pest levels. Ten families of birds are specifically exempted from the provisions of the law, though their importation could be restricted by many other applicable U.S. laws. Hawaii Tropical Forest Recovery Act of 1992 The Hawaii Tropical Forest Recovery Act (P.L. 102-574; 16 U.S.C. 4503(note)) amended the International Forestry Cooperation Act to create a variety of measures to address the problems of the native forests of Hawaii. The introduction of such non-native species as pigs, goats, and mosquitoes has been a major threat to the integrity of native Hawaiian forest ecosystems, and the Act has several features that address these issues. The Secretary of Agriculture is authorized to develop a program to assist Hawaii and U.S. territories, through the Forest Service, to protect native species from non-native species, and to establish biological control agents for the non-natives. The Secretary must also develop plans for the Institute of Pacific Islands Forestry and for the Hawaiian tropical forests which must, among other things, provide for the study of biological control of non-native species. CRS-33 In addition, the Act created a short-term task force of specified federal, state, and other individuals. Among its other responsibilities, the task force was to develop an action plan to “promote public awareness of the harm caused by introduced species” and develop recommendations on “the benefits of fencing or other management activities for the protection of Hawaii’s native plants and animals from non-native species, including the identification and priorities for the areas where these activities are appropriate.” The report has since served as the framework for Forest Service management and research budget requests in this area. There has been a modest increase in funds to support invasive species research and eradication efforts, as well as a specialist to oversee management activities on invasive species. Plant Protection Act of 2000 The Plant Protection Act of 2000 (PPA) (7 U.S.C. 7701 et seq.) consolidated several plant quarantine authorities, some dating back to the 1880s. It gives the Secretary of Agriculture the authority to prohibit or restrict the importation, exportation, and the interstate movement of plants, plant products, certain biological control organisms, noxious weeds, and plant pests.62 The statute also gives the Secretary the authority to inspect foreign plant imports, to quarantine any state or premise infested with a new pest or noxious weed, and to cooperate with states in certain control and eradication actions. These authorities have been traditional hallmarks of U.S. plant pest regulations, and are administered by APHIS in collaboration with state departments of agriculture and their plant protection boards. Traditionally, all states have some type of domestic quarantine laws but federal regulations preempt state actions in interstate commerce. The new Plant Protection Act, however, allows states to petition the Secretary for “special needs” exceptions to federal rules. Exceptions granted by the Secretary would allow states more control over movement of certain plant material across their borders. Regulations for applying the new petition process have not yet been issued, but the Secretaries still would retain the power to grant these “special need” petitions. The new law also allows individuals or states to petition the Secretary of Agriculture to add or remove plant pests from federal regulation. Regulation of foreign and interstate plant movement has been important to prevent or limit the spread of a harmful non-native species in the United States. The new law seeks to give more power to states to influence the list of invasive species that would be federally regulated. 62 The PPA became law in June 2000 as part of the Agricultural Risk Protection Act (P.L. 106-224). This law consolidated and superceded several U.S. plant health laws, including: (a) The Act of August 20, 1912 (commonly known as the “Plant Quarantine Act”, 7 U.S.C. 151-164a, 167); (b) The Federal Plant Pest Act (7 U.S.C. 150aa et seq. and 7 U.S.C. 147a); (c) Section 102 (a) - (e) of the Department of Agriculture Organic Act of 1944 (7 U.S.C. 147a); (d) The Federal Noxi [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/crs%3ARL30123. Public record. Not legal advice.