Bonneville Cutthroat Trout (Oncorhynchus Clarki Utah)
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Bonneville Cutthroat Trout (Oncorhynchus clarki utah) Data: Range-wide Status (May and Albeke 2005) - Updated in 2010 and 2015 Partners: Bureau of Land Management, Confederated Tribes of the Goshute Reservation, Idaho Game and Fish Department, National Park Service, Nevada Department of Wildlife, Trout Unlimited, Utah Division of Wildlife Resources, Wyoming Game and Fish Department, US Fish and Wildlife Service, US Forest Service, Utah Reclamation Mitigation and Conservation Commission ii | Western Native Trout Status Report - Updated January 2018 Species Status Review to catch, and most populations are managed through the use of fishing regulations that The Bonneville Cutthroat Trout (BCT) is protect population integrity and viability. In ad- listed as a “Tier I Conservation Species” by the dition, many BCT populations occur in remote State of Utah, as a “Sensitive Species” by the locations and receive limited fishing pressure US Forest Service, as a “Rangewide Imperiled making special regulations unnecessary. Due (Type 2) Species” by the Bureau of Land Man- to protective regulations and/or the occurrence agement, and as a “Vulnerable Species” by the of BCT in remote areas, over-fishing is not State of Idaho. This species has been petitioned considered to be a problem at this time. Short- for, but precluded for, listing as Threatened or term fishing closures are often imposed to Endangered by the US Fish and Wildlife Ser- promote the development of recently re-intro- vice several times in the past decade. The most duced populations of BCT. Spawning season recent determination, that the species does not closures are frequently used, particularly for warrant listing as a threatened or endangered brood populations. Other regulations requiring species under the Endangered Species Act was limited harvest, length restrictions (slot limits), released on September 9, 2008. catch-and-release, and terminal tackle restric- tions have demonstrated effectiveness in main- The State of Utah Conservation Agreement and taining populations of BCT. Special regulations Strategy (CAS) for Bonneville Cutthroat Trout are very popular with some groups of anglers. was completed and signed by all parties in 1997 BCT (particularly the Bear Lake strain) are (Lentsch et al. 1997). The Range-wide Conser- cultured extensively in the State of Utah, and vation Agreement and Strategy was completed used widely in sport fish management pro- in 2000 (Lentch et al. 2000) and updated in grams. Angler support for BCT conservation 2018 (Oplinger et al. 2018). In 2004, the Utah management programs is strong in all four Conservation Team completed a Post Imple- states and is an important asset to conservation mentation Assessment to present progress and and management programs. accomplishments in BCT conservation in the State of Utah. Also during 2007, a comprehen- BCT Distribution sive Range-wide Status Review was published. A Management Plan for Conservation of Based on the 2015 Range- wide Status Update, BCT in Idaho was submitted during 2006. The At least 202 BCT populations collectively oc- Nevada Conservation Agreement and Strategy cupy about 2,728 miles of stream habitat in 21 was also finalized during 2006. watersheds in Utah, Idaho, Nevada, and Wyo- ming. These populations qualify as conservation BCT Sportfishing Status populations under standards developed by the States. Of the 202 conservation populations, 55 BCT are considered a game fish by all state, percent are considered core populations. federal, and tribal agencies that have manage- Conservation populations have at least 90 per- ment authority for this subspecies. Like other cent cutthroat trout genes and core populations cutthroat subspecies, BCT are generally easy have at least 99 percent cutthroat trout genes. BONNEVILLE CUTTHROAT TROUT (Oncorhynchus clarki utah) | III Of the 2,728 miles of occupied habitat, 1,160 Thirty-three of these populations representing miles (49%) are associated with lands adminis- 1,509 miles existed in drainages with strong or tered by the Federal Government. Almost 51% moderate connectivity. of BCT habitat occurs on land with non-fed- eral administration, including Goshute Tribal BCT Habitat Requirements lands (12 miles). Typical of most trout, BCT thrive in lotic habitats characterized by relatively cool, well Range and GMUs of the BCT oxygenated water; the presence of clean, well sorted gravels with minimal fine sediments for successful spawning; and habitat complexity composed of large woody debris and overhang- ing banks. However, BCT have been found to tolerate marginal habitat conditions as well (i.e., widely variable flows, high temperatures, poor instream structure, and high turbidity) due to the fact that they evolved in a desert environment. One study (Kershner 1995) found spawning substrate size to be proportional to body size. For example, large adfluvial BCT typically spawn in large gravels or cobbles, while smaller, stream resident BCT spawn over coarse sand or small gravels. Concerns and Issues Relative to the Conservation and Im- provement of BCT Primary threats include isolation of streams, BCT Range and GMUs habitat quality, oil and gas development, re- source extraction, grazing, water management, A total of 202 separate BCT populations cur- rently occupying 2,303 miles of habitat were and climate change. designated as “conservation populations” (84% of currently occupied habitat). These conser- vation populations were spread throughout the historical range, occurring in 19 of the 23 hydrologic units historically occupied by BCT. iv | Western Native Trout Status Report - Updated January 2018 Genetic Considerations Habitat Concerns Most of the western states that have manage- Continued habitat degradation is one of the ment and conservation authority for cutthroat major threats to the abundance and improve- trout participated in the development of a posi- ment of BCT. Loss of habitat quality has been tion paper on genetic management (Lentsch et recognized as one of the two major human- al. 2000). This position paper describes a hier- induced influences in the loss of BCT popula- archical classification for conserving cutthroat tions. Major habitat concerns: trout that includes: • Modification and fragmentation of habi- 1) a core component of genetically unaltered tat from barriers to fish passage, entrain- populations or individuals; ment, and thermal barriers due to dams and water diversions. 2) designated conservation populations that may be either genetically unaltered or slightly • Aquatic habitat degradation and altera- introgressed and have attributes worthy of tion from mining, forestry and agricul- conservation; and tural land use practices that result in sediment loading, elevated temperatures, 3) populations that are managed primarily for changes to stream structure and mor- their recreational fishery value. phometry, and changes in water quality. Core populations are recognized as having im- • Flow depletion and water quality degra- portant genetic value and could serve as donor dation due to water diversions for hydro- sources for developing either captive or wild power, municipal and agricultural uses, broods or for re-founding additional popula- and groundwater pumping for urban, tions from existing BCT populations. mining, and power production. Management of conservation populations will • Secondary impacts of dams from res- emphasize conservation, including potential ervoir pools in large river systems (i.e., conservation populations. The Range-wide hydro-power entrainment, gas super- BCT Status Report provided a generalized saturation, modification of flow patterns, population health assessment for each conser- creation of nonnative fish habitat, and vation population based on population de- changes in tailwater water temperatures). mographics/productivity, temporal variability, connectivity, and size. Seventy-one BCT popu- • Climate change influences, such as lations (46%) were rated as having either high warmer water, changes in stream flow, general health (11 populations) or moderately and the increasing frequency and intensi- high general health (60 populations). Fifty-six ty of disturbances (Williams et al. 2008). populations (37%) were rated as having mod- The accumulation of these detrimental influ- erately low general health and 26 populations ences through time has led to isolation and (17%) were rated as having low general health. fragmentation of habitat and reductions in range, which adversely impact the stability and viability of BCT populations. BONNEVILLE CUTTHROAT TROUT (Oncorhynchus clarki utah) | V Disease Concerns tamination. Thirty-four populations (17%) were rated as being at high genetic risk. A disease risk assessment was made for each conservation population using a ranking of 1 to Population Viability Concerns 5 based on the level of risk with a ranking of 1 being the lowest level and 5 being the highest For the purposes of conservation and recovery, level. BCT populations in the four states have been partitioned into a hierarchical classification Population isolation and security were impor- system. A sub‐basin or basin where a group of tant considerations, but they were not viewed genetically pure local populations may share as absolutes. Diseases of concern included, but common foraging, spawning, migrating, or were not limited to, whirling disease, furuncu- over‐wintering habitat and function as a meta‐ losis and infectious pancreatic necrosis virus. population are termed “Core populations”. Other