Alaska Region Pathways Animal Introductions Alaska Has a Long History of Animal Tricia L
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This work was supported in part by the U.S. Department of Agriculture, Forest Service. The findings and conclusions in this publication are those of the authors and should not be 336 construed to represent any official USDA or U.S. Government determination or policy. Appendix: Regional Summaries Alaska Region Pathways Animal Introductions Alaska has a long history of animal Tricia L. Wurtz and Bethany K. Schulz introductions, especially on its islands (Bailey 1993; Paul 2009). The frst deliberate releases of Arctic foxes (Vulpes Introduction lagopus) for fox ranching on several Aleutian Islands Alaska has fewer invasive species and is less impacted by occurred in 1750 (Black 1984); the frst known accidental invasive species than most places on Earth. Until recently, release of Norway rats (Rattus norvegicus) was prior to 1780 Alaska has been protected by its cold climate and by its via a shipwreck (Brechbill 1977). The rats spread so comparative lack of roads and other development. prolifcally that the island where the shipwreck occurred However, these barriers are eroding. Warming climate later came to be known as Rat Island (Ebbert and Byrd 2002). trends and longer shoulder seasons have reduced the cli- It was the site of an intensive, successful rat eradication mate flter that so far may have prevented some invasive effort in 2008 for the purpose of restoring seabird nesting species from establishing in the State (Figs. A1.1 and A1.2; habitat (Croll et al. 2016; Dunham 2012; Fritts 2007; USFWS Carlson et al. 2015; Jarnevich et al. 2014; Sanderson et al. 2007). Cattle (Bos taurus), Sitka black-tailed deer 2012; Wolken et al. 2011). More extensive wildland fre (Odocoileus hemionus sitkensis), and elk (Cervus canadensis) combined with increasing activity in mining, oil and gas have all been released on islands in Alaska and have proven extraction, and wilderness tourism are extending the net- diffcult to manage or remove when their populations thrived work of travel corridors and altered landscapes that are beyond intention or when management objectives changed vulnerable to the establishment and spread of invasive spe- (Ebbert and Byrd 2002). cies (Cortes-Burns et al. 2008; Spellman et al. 2014). With 10,680 km of coastline and at least 2670 named islands, Alaska encompasses a very large geographic area, and Alaska is also vulnerable to invaders in the nearshore species that occur naturally in one part of the State may marine environment. behave invasively and problematically when introduced to Invasive species have been introduced to Alaska via a another. Two prime examples are northern pike (Esox lucius) variety of pathways. Plants have been intentionally and Alaska blackfsh (Dallia pectoralis), both of which are introduced for agricultural and commercial purposes, and native to parts of Alaska north or west of the Alaska Range. non-native animals have been introduced for subsistence and Both have been illegally transplanted to Southcentral Alaska, sport hunting. Many introductions of invasive species to starting in the 1950s, resulting in a number of established Alaska, however, have been unintentional. Such pathways populations. The diets of introduced blackfsh are similar in include contaminants in agricultural or forestry products; the composition to the diets of native juvenile salmonids movement of contaminated road vehicles, boats, and aircraft; (Oncorhynchus spp.) and stickleback (Gasterosteus and the disposal of live animals and plants from aquaria. aculeatus and Pungitius pungitius), pointing to the potential Problem species span many taxa: both terrestrial and aquatic for competition for prey between blackfsh and native fsh plants, mammals, birds, fsh, insects, earthworms, and a species (Eidam et al. 2016). Northern pike are highly marine tunicate. predatory; where introduced, they have greatly reduced the Fig. A1.1 The Alaska region Appendix: Regional Summaries 337 Fig. A1.2 Current known distribution of non-native plant species in the Alaska Exotic Plant Information Clearinghouse database (https:// Alaska, shown with the projected change in annual mean temperature accs.uaa.alaska.edu/invasive-species/non-native-plants/); climate from the reference period 1970–1999 to the future period 2030–2059. projections are from the US Department of the Interior Alaska Climate The projected climate is the average of fve climate model projections Science Center. (Data courtesy of Scenarios Network for Alaska and (CMIP5) for a higher emissions scenario (RCP 8.5). Plant data are from Arctic Planning (SNAP 2016)) presence of native fsh species. Rutz (1999) identifed fve tural species were later repurposed for erosion control dur- species of Pacifc salmon juveniles in the stomachs of har- ing road construction, mineral exploration, and mine vested pike in the Susitna River drainage, with coho salmon reclamation. This enlarged the area occupied by the intro- (O. kisutch) juveniles in 59% of non-empty stomachs. The duced species, providing a greater source for further Alaska Department of Fish and Game considers northern spread. Horticultural activities have greatly increased the pike to be the highest-priority invasive threat in Southcentral variety of species being introduced, again both intention- Alaska (ADFG 2002). ally—such as Japanese knotweed (Fallopia japonica), Siberian peashrub (Caragana arborescens), European bird Agriculture and Horticulture Several of Alaska’s most cherry (Prunus padus), Maltese cross (Silene chalcedon- aggressive invasive plant species were initially introduced ica), and orange hawkweed (Hieracium aurantiacum)— through agriculture, either for forage (e.g., reed canary and inadvertently such as perennial sowthistle (Sonchus grass (Phalaris arundinacea), bird vetch (Vicia cracca)) or arvensis) in the soil of containerized imported ornamental to improve soils (e.g., white sweetclover (Melilotus plants (Conn et al. 2008a). Imported hay and straw have albus)), or accidentally through seed mix impurities (e.g., been shown to carry a variety of viable weed seeds (Conn creeping thistle (Cirsium arvense)). Some of these agricul- et al. 2010). 338 Appendix: Regional Summaries Shipping In recent years, introductions have increased in 1000-km northward extension of the range of this species frequency and opportunity through trade (Carlson and along the West Coast of North America (Cohen et al. 2011). Shephard 2007). Shrink-wrapped bundles of frewood The attention it garnered has led to a multi-organization originating in Washington State and sold in Fairbanks were effort to test control options (McCann et al. 2013). found to harbor fve species of living insects, including two exotic bark beetles (FS-R10-FHP 2012). European and Asian Aquarium Release Aquatic plants of the genus Elodea are gypsy moths (Lymantria dispar) have been detected in native to much of North America but are not native to Alaska. Alaska (either captured in insect traps or intercepted in ports) The genus is widely used in aquaria, and in fact elodea was seven times since 1985 (FS-R10-FHP 2012). The European likely frst introduced to Alaska’s wild waterways by aquar- gypsy moth egg masses were likely carried north from the ium dumping. Since the initial fnd of a small amount of elo- lower 48 States on recreational vehicles; the Asian egg dea in Eyak Lake in 1982, it has been found in more than 20 masses were found on cargo ships from Asia. locations around the State, with several infestations occur- ring in urban lakes and waterways in Anchorage and Recreational Activities Several taxa are known to have Fairbanks (FS-R10-FHP 2016). It was released from aquaria been introduced or spread through recreational activities. (one infestation is immediately behind an elementary school) Non-native plants are common along most of the hiking and has spread via boats, foatplanes, and downstream water trails in the Kenai Mountains, but are rare within natural veg- fow (FS-R10-FHP 2016). Once established in a lake or etation communities of the area, suggesting that the plants slow-moving waterway, elodea grows aggressively (Figs. were introduced by trail users or trail maintenance activities A1.3 and A1.4), with the potential to degrade fsh habitat, (Bella 2011; Develice 2003; Ware et al. 2012). Three species displace native fora and fauna, impede boat travel and safe of non-native earthworms (Lumbricidae) have been intro- foatplane operation, decrease water fow rates, and increase duced on Alaska’s Kenai Peninsula, with at least one of them sedimentation rates (Luizza et al. 2016). The amount of suit- arriving via bait abandonment by anglers (Saltmarsh et al. able habitat for this species in Alaska is projected to increase 2016). with the warming climate (Luizza et al. 2016). If elodea con- tinues to spread in Alaska, it may pose direct negative Transport of Aquaculture Gear A marine tunicate invader, impacts on subsistence practices related to Chinook salmon “D-vex” (Didemnum vexillum), was discovered in Sitka’s (O. tshawytscha) and whitefsh (Coregonus nelsonii), thereby Whiting Harbor in 2010. D-vex is known to foul shellfsh posing a major challenge to Alaska Native communities aquaculture gear, hamper scallop movement, and overgrow (Luizza et al. 2016). Elodea is already challenging Alaska’s extensive areas of benthic habitat. This fnd represented a natural resource managers. Small infestations on the Kenai Fig. A1.3 Dense stands of the invasive aquatic plant elodea in a waterway near Fairbanks, AK, and close-up view of elodea (inset). (USDA Forest Service photos) Appendix: Regional Summaries 339 Fig. A1.4 Elodea washed up on the shore of Eyak Lake, in spring 2016. (USDA Forest Service photo) Peninsula and the Anchorage Bowl have been successfully erichsonii), an insect native to Europe, impacted an esti- treated with aquatic herbicides (Morton et al. 2014), but get- mated 240,000 ha of interior Alaska, killing roughly 80% of ting control of the State’s larger and more challenging infes- the larch trees (Larix laricina) in the affected area (Burnside tations (some in remote locations, some in fowing water) et al. 2010). In 2010, the green alder sawfy (Monsoma pul- will take signifcant funding and cross-agency cooperation.