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The Colorado River basin, its Native and Non-native Fishes, and the Potential for Application of Genetic Biocontrol to the Conservation of an Imperiled Fauna Paul C. Marsh Marsh & Associates, LLC Historical Setting • • • • • • Isolated for millennia Depauperate ichthyofauna Six freshwater families; 53 +/- taxa 48 of 53 (91%) of these taxa are endemic Three marine/estuarine families, 3 species 56 +/- total taxa Native Freshwater Families Salmonidae: 4 taxa Cyprinidae: 27 taxa Catostomidae: 9 taxa Native Freshwater Families Cyprinodontidae: 10 taxa Poeciliidae: 1 taxon Cottidae: 2 taxa Native Marine/Estuarine Fishes Elopidae Mugilidae Eleotridae XXX XXX X X XXX XXX XXX XXX XXX XXX XXX XXX XXX XXX How Did We Get Here? • Physical changes • Socio-politics and economics • Non-natives Regional drought, livestock grazing, logging, road building dam building and impoundment channelization Sociopolitical & Economic Factors • • • • Absence of protections until the late 1960s Lack of interest Failed management of native fishes Aggressive development and promotion of sport fisheries • Lack of cooperation at state and federal levels (e.g., RIP, MSCP) Non-native Biota Non-native Fishes in the Colorado River Basin • 24 families • About 100 species • Origins – – – – – eastern North America Mexico & Central America Atlantic and Pacific oceans Africa Asia Families of Non-native Fishes • • • • • • • • • • • • Acipenseridae Anguillidae Clupeidae Salmonidae Osmeridae Esocidae Characidae Cyprinidae Catostomidae Ictaluridae Clariidae Loricariidae • • • • • • • • • • • • Rivulidae Fundulidae Goodeidae Poeciliidae Cichlidae Atherinopsidae Centrarchidae Moronidae Haemulidae Sciaenidae Percidae Cottidae Non-native Fishes • The single most significant obstacle to the successful recovery of native fishes • The IUCN “Invasive Species Specialist Group” lists 100 of the world’s worst invasive alien species, and the list includes eight fishes. Six of those eight are established (all intentionally introduced) in the Colorado River basin, and another has been recorded but apparently never took hold. IUCN “100 Worst” List Fishes • While the underlying causes of invasive species threats are significant and global in nature, the threat can effectively be dealt with at the local site level, especially through prevention, early detection and rapid response (www.issg.org/about_is.htm). • Prevention does not exist, detection often is serendipitous, and response rarely is rapid, if at all. Two Colorado River Basin Examples • Green sunfish Lepomis cyanellus • Western mosquitofish Gambusia affinis Green sunfish Lepomis cyanellus Western mosquitofish Gambusia affinis Pluses of Genetic Biocontrol in the Colorado River System • Selective for the target species • If species-specific, would not threaten non-target species including sport fishes • No secondary or collateral damage to the system or its biotic components • Could treat entire watersheds, might not require emplacement of barriers • Potentially less expensive to implement • Eliminates piscicide-related issues such as registration, human health effects, etc. Potential Issues – Nothing New • • • • Containment Unintended effects on non-target species Effectiveness limited in time and/or space Does not ensure or alleviate issues of project support by agencies or the public • Does not mitigate the conflict between sport fishes and native fishes • Addition of genetically-modified organisms to a water body could temporarily increase impacts to natives • Public distrust of genetic manipulation could result in lack of support or outright opposition The Bottom Line Acknowledgements Rob Clarkson (Reclamation) Tom Dowling (Arizona State University) Abe Karam & Brian Kesner (Native Fish Lab at M&A) Jerry Stefferud (Forest Service, Ret.) Sally Stefferud (Fish & Wildlife Service, Ret.) Introductory Remarks • Not going to hear anything not already heard, but for a different place and different fauna • Perhaps learn a few things about the Colorado River system and its native fishes • Non-native fishes are a problem in the basin, and genetic biocontrol might be a useful tool • Do not represent a management agency and am not burdened with the task of issuing a “company line” • The “take home” message is that native fishes are in desperate need and can use all the help they can get Geographic Setting • SW United States (AZ, CA, CO, NM, NV, UT, WY) and NW Mexico (BCN, Son) • Three geographic provinces: Rocky Mountains, Colorado Plateau, and Basin & Range • Drains 632,000 km2 (1/12th of the continental United States • 2320 km long (2725 km via Green River) • Elevations from >4,000 m to below sea level • mouth at the Sea of Cortez (Gulf of California) In the lower basin the river and its tributary streams flow through some of the hottest and driest deserts on the continent Historical Setting • • • • • • Isolated for millennia Depauperate ichthyofauna Six freshwater families; 53 +/- taxa 48 of 53 (91%) of these taxa are endemic Three marine/estuarine families, 3 species 56 +/- total taxa Status of the Freshwater Fauna • • • • 3 (5%) species extinct 17 (32%) species endangered 7 (13%) species threatened 12 (23%) species state listed, special concern, or under conservation agreement • 39 of 53 (74%) taxa are in trouble, or gone How Did We Get Here? • Landscape changes wrought by regional drought and land uses (grazing, logging, roads, housing, etc.) • Loss of habitat or habitat suitability (desiccation, thermal alteration, loss of habitat complexity, loss of interconnectedness) • Dams, impoundment & channelization • Socio-political and economic factors • Introduction & establishment of non-native biota Introductions of Non-native Biota • • • • • Fishes Invertebrates Parasites Disease organisms Plants Non-native Fishes • The single most significant obstacle to the successful recovery of native fishes • The IUCN “Invasive Species Specialist Group” lists 100 of the world’s worst invasive alien species, and the list includes eight fishes. Six of those eight are established (all intentionally introduced) in the Colorado River basin, and another has been recorded but apparently never took hold. • A majority of non-native fishes are implicated in conflicts with native species. • Mechanisms of interaction include – Predation & competition – Hybridization (especially among trouts) – Novel parasites and diseases Green sunfish • One of the most invasive, pervasive, and destructive species in the basin, although not even recognized as an invasive species by some states • Implicated in declines of a diversity of native fishes including stream dwelling chubs (Gila spp.), “big river” razorback sucker Xyrauchen texanus, and Colorado squawfish (Ptychocheilus lucius) (Marsh & Langhorst 1988, Tyus & Carp 1990 Dudley & Matter 2000) • • • • • • Bass & sunfish family (Centrarchidae) Native to eastern North America First records in the 1920s Ubiquitous in the Colorado River basin Small (maximum length near 35 cm) Predaceous on native fish larvae & early juveniles of all species, and adults of some • Not a desired sport fish, and not intentionally stocked or managed • Current control technologies include chemical treatment and mechanical removal • Has proven difficult to eradicate, or to keep systems free of this pest • Is widespread and thus available to reinvade naturally, or with help. • Can occupy all sizes of lotic waters from tiny streams to large rivers, and lentic waters from small ponds to large reservoirs • Its range continues to expand Western mosquitofish • Perhaps the most widespread invasive species worldwide, and one of the most pervasive in the Colorado River basin, especially in warmer, southerly regions • Implicated in declines and local extirpations of its con-familial native Gila (Sonora) topminnow (Poeciliopsis occidentalis) and a diversity of other native fishes wherever the two kinds co-occur (Minckley & Meffe 1987, many others) • Live-bearing reproductive mode could create both challenges and opportunities for development of an effective biocontrol technology • • • • • • Livebearer family (Poeciliidae) Native to southeastern United States First records in the 1920s Ubiquitous in the Colorado River basin Diminutive (maximum length near 35 mm) Predaceous on native fish larvae & early juveniles of all species, and adults of some • Current control technologies and issues are similar to those for green sunfish • Mosquitofish are stocked routinely by counties and private parties for mosquito control. Its range continues to expand. • Ironically, native topminnow and desert pupfish (Cyprinodon macularius) are equally effective in this role, but not used because of permitting and other issues Existing Major Programs UCRB-RIP. 4 listed big-river fishes, multiple partners. Upper Colorado River basin. Goal: recovery with development Originally 15 yrs (1988-2003), extended until 2023 Original budget $67 million, total could exceed $150 million. 60% DOI, 28% power revenues, 12% others San Juan River RIP. 2 listed big-river fishes, multiple partners. San Juan River mainstream. Goal: recovery with development Originally 15 yrs (1992-2007), extended until 2023 Expended $17.8 m 2001-2009, could expend another $28 m. 79% DOI, 21% others CAP Fund Transfer Program. Gila River basin, 4 listed stream fishes, BR/FWS+AZ/NM. 2 parts: conservation actions and non-native control. Gila River basin. Goal: conservation with operations 25 years (1997-2022), $12.5 m budget. 100% Reclamation. LCR MSCP. 31 species including 3 listed and 1 non-listed big-river fishes, multiple partners. Lower Colorado River mainstream. Goal: conservation with operations 50 years (2005-2055), $626 m budget. 50% DOI, 50% states (25% CA, 12.5% AZ/NM) • Native fish conservation and recovery in the Colorado River basin has cost hundreds of millions of dollars since the inception of active implementation programs more than two decades ago • Most target and other native fishes are inarguably in worse shape today than when protection and management began with the ESA nearly four decades ago • Traditional habitat management strategies have not been effective because of the presence of non-native fishes • Control of non-native fishes is problematic The Bottom Line • Genetic biocontrol is an important tool that needs to be developed and applied in the basin • Develop alongside other novel controls such as species-specific piscicides • Could provide recovery opportunities where they currently do not exist or are logistically impractical • Could eliminate or reduce the need for current controls such as barriers, piscicides, or mechanical removal extras