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Freshwater invasive species: a double-edged sword?organized by Jennifer Molnar (The Nature Conservancy), Carmen Revenga (The Nature Conservancy), and Mordecai Ogada (Nairobi, Kenya)THE DISTRIBUTION OF FRESHWATER INVASIVE SPECIES AND THEIR IMPACTS: RESULTS FROM A GLOBAL THREAT ASSESSMENT JENNIFER MOLNAR and Carmen Revenga, The Nature Conservancy, Seattle, WA, USA (JR) and Washington, D.C., USA (CR), jmolnar@tnc.org Invasive species have been highlighted as one of the major pressures on native biodiversity; however, even basic data on the presence or absence of invasive species at a global level are often inconsistent and only available for limited geographic areas. We present the results of a global threat assessment of freshwater invasive species. Building on existing datasets, we integrated information from a wide variety of sources and developed a geographically-referenced database of the freshwater invasive species. Non-native distributions were documented by freshwater ecoregion. Where the data allow, we have scored the threat of each species to native biodiversity by the following categories: ecological impact, geographic scope, invasive potential, and management difficulty. Due to limited data availability, our assessment has some significant geographic and taxonomic gaps that will be filled in the future with additional local and site-level datasets and information. Our initial analysis, however, allows us to assess broad patterns of freshwater invasive species presence and their threat to natural habitats and biodiversity globally. GLOBAL LINKAGES: FORECASTING THE OCCURRENCE, SPREAD AND IMPACT OF FRESHWATER NONINDIGENOUS SPECIES DAVID LODGE, Center for Aquatic Conservation, University of Notre Dame, Notre Dame, IN, USA, dlodge@nd.edu Invasive species are a major driver of global changes in freshwater community structure and ecosystem function. Until recently, however, ecologists had little capacity to forecast—and therefore prevent—the introduction, spread and impact of species likely to cause net financial or environmental harm. Forecasting capacity is now well developed for some stages of invasions, some ecosystems, and some taxonomic groups. This is especially true for intentional pathways (e.g., pet and horticultural industries). Forecasting capacity for introductions via unintentional pathways (e.g., ship ballast water or hull fouling) is also growing rapidly, but many logistical and technical challenges remain in research. In addition, the science-policy interface is dramatically underdeveloped. For science to better inform management and policy, it is essential to integrate the emerging forecasting capacity into international (e.g., World Trade Organization SPS) and national (e.g., USDA noxious weed and plant pests, Lacey Act injurious wildlife) regulatory risk assessment protocols, as well as into voluntary protocols in the private sector. MINIMIZING THE EFFECTS ON NATIVE FAUNA OF INTRODUCED FISH SPECIES FOR FOOD SECURITY IN DEVELOPING COUNTRIES Devin Bartley and DAVID COATES, Fisheries Department, Food and Agriculture Organization of the United Nations, Italy (DB), Secretariat of the Convention on Biological Diversity, Montreal, Canada (DC), david.coates@biodiv.org Alien species within fisheries and aquaculture have made significant contributions to food security in many countries, but adverse impacts have arisen and need to be minimized in the future. It is useful to distinguish between invasive alien species causing net losses in ecosystem function, and those alien species offering significant benefits with reduced risk of invasiveness. Determining the potential invasiveness of a species is critical to risk management. Pre-introduction assessments of benefits and risks should be undertaken, using a code of practice or similar arrangement. Once species are in use, risks can be further reduced through the management of releases from aquaculture facilities. Risks of establishment can be further reduced through the production of sterile stock. However, most developing countries do not have management infrastructures in place to manage risks after importation. Pre-introduction assessments remain the first, and possibly only, line of defense in many countries. Policies that shift emphasis from the use of alien to native species may not necessarily lead to net gains in biodiversity conservation. In many cases, the use of well-known, easily managed alien species, particularly where they already occur, can be preferable to undermining local genetic diversity through the poor hatchery management of native species. IMPACTS AND USES OF EXOTIC SALMONIDS IN PATAGONIA, FROM THE POND TO THE OCEAN SHELF MIGUEL PASCUAL, Centro Nacional Patagonico, Chubut, Argentina, pascual@cenpat.edu.ar Exotic salmonids are widely distributed in lakes, rivers, and oceans throughout Patagonia. They are top predators, with far reaching effects on receiving communities. They also constitute highly prized food items and trophy recreational fish. Salmonid populations, as well as related activities, span across boundaries, from private to public, from municipal to provincial, from national to international. In this presentation I use three examples of contrasting scale to illustrate some of the main problems and challenges posed by exotic species of commercial value in freshwater systems of Patagonia: trout aquaculture in shallow fishless lakes, trout recreational fisheries in lakes and rivers, and marine net pen salmon aquaculture. For each of these case studies, I analyze positive and negative impacts brought by exotic salmonids and discuss the prospects for finding win-win situations between use and conservation. ECOLOGY AND ECONOMY: THE TRADE-OFF IN AQUATIC SPECIES INTRODUCTIONS IN KENYA MORDECAI OGADA, Nairobi, Kenya, mordyogada@yahoo.com Kenya’s major aquatic invasive species were introduced deliberately with beneficial objectives, but with mixed results. The species are the brown trout (Salmo trutta), large mouth bass (Micropterus salmoides), Louisiana crayfish (Procambarus clarkii), and Nile perch (Lates niloticus). The trout is a predator in highland aquatic ecosystems, but this species has never established itself and this reduces its impact. This is out-weighed by the fees paid by fly fishermen to catch them. The Nile perch eliminated over 200 fish species from Lake Victoria and became the mainstay (92%) of the local fishing industry, bringing in significant economic gains. Large mouth bass eliminated most cichlid species from Lake Naivasha, and made up 78% of the local fish catch. However, these gains have now been compromised by over-exploitation. The Louisiana crayfish established itself in most lowland aquatic ecosystems, causing losses of up to 75% of aquatic biodiversity, but currently bringing no economic gains. Economic gains from aquatic invasives are subject to many unpredictable variables, but ecological losses are guaranteed and often permanent. From Kenya’s experience, gains should be sought from the invasives that are already there, but there isn’t any economic gain large enough to justify introduction of new ones. CLASSIFICATION AND ZONING OF RIVERS: A TOOL FOR CONSERVING THREATENED SPECIES AND MANAGING ALIEN FISH SPECIES WITH SOCIO-ECONOMIC VALUE PIERRE DE VILLIERS, Orange Vaal Yellowfish Conservation and Management Association, Bloemfontein, South Africa, yellowfish@lantic.net The concept of zoning rivers or sections thereof is being developed in order to be able to conserve threatened species as well as to manage established alien species that have a high socio-economic value. Both of these tasks could not be addressed by managers in South Africa using one specific legislative act, so they are using several new acts, promulgated by different government departments, in a cooperative way to carry out the necessary conservation and management measures. These acts may be used to facilitate the identification, classification, conservation, and management of specific aquatic habitats or zones and the species therein. The identification of these zones is being done in parallel to the listing of threatened species and alien species. No new alien species will be imported into South Africa or released in waters in South Africa without a full risk assessment. This use of identifying river zones will be discussed using the Largemouth Yellowfish (Labeobarbus kimberleyensis) and Rainbow Trout (Oncorhynchus mykiss) as examples. PREDICTING THE IDENTITY AND IMPACTS OF FRESHWATER INVASIVE SPECIES REUBEN KELLER, David Lodge, David Finnoff, and John Drake, Department of Biological Sciences (RK) and Center for Aquatic Conservation (DL), University of Notre Dame, Notre Dame, IN, USA, Department of Economics and Finance, University of Wyoming, Laramie, WY, USA (DF), National Center for Ecological Analysis and Synthesis, Santa Barbara, CA, USA (JD), rkeller2@nd.edu The trades in live non-indigenous organisms introduce species that have net benefits and species that become invasive (i.e., cause net economic and/or environmental harm). Preventing the introduction of invasive species is necessary to maximize the value of these trades, and this requires knowing the species in trade and assessing their risks of becoming invasive. Until recently, however, risk assessments were not accurate enough to be applied economically because they mistakenly excluded many beneficial species. Accuracies have recently improved and we have used a bioeconomic framework to test their utility. We show that under many situations it is economically rational to apply risk assessments with currently attainable accuracies. Next, we have surveyed the trades in aquatic organisms in the Laurentian Great Lakes region to identify the species being introduced. We show that these trades pose risks of spreading known invaders, and of introducing new invaders. To address one taxon, we have constructed a risk assessment for mollusks that can be used to determine the invasion risk posed by any species. These methods—identifying species in trade and assessing the risks posed—are applicable to many taxa and ecosystems, and have the potential to greatly reduce damages from invasive species. USES AND NEEDS FOR CODES OF PRACTICE FOR THE INTRODUCTION OF ALIEN SPECIES DAVID COATES and Devin Bartley, Secretariat of the Convention on Biological Diversity, Montreal, Canada (DC), Fisheries Department, Food and Agriculture Organization of the United Nations, Italy (DB), david.coates@biodiv.org Despite a long history of development, dating from the late 1960s, codes of practice remain largely unused, even in regions where they were developed. An analysis is made of the reasons why codes have not been widely adopted in practice. The original codes are often difficult to implement, particularly in developing countries and under technical capacity constraints. Genuine motivation to use codes has also been widely lacking. The basic elements of a code are simple, involving a process of impartial risk assessment and decision making, but often institutional arrangements do not create the opportunity or ability to undertake such assessments. Suggestions are made for improving codes and their use particularly for developing countries. Codes must be developed and applied locally and promoted regionally. They need complementary guidance on undertaking assessments and proceeding with limited capacity. The greatest shortcoming of codes is the limited guidance on assessments of economic and social benefits (and risks) of introductions. The majority of assessments would conclude that proposals offer insufficient benefit to warrant more detailed consideration. A significant opportunity is to promote and use codes alongside existing institutional arrangements for the management of animal health (quarantine), avoiding the need for parallel capacity building programs. | |||||||||||||||||
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