Common use of REDUCE NEGATIVE IMPACTS OF NONNATIVE FISHES AND SPORTFISH MANAGEMENT ACTIVITIES Clause in Contracts

REDUCE NEGATIVE IMPACTS OF NONNATIVE FISHES AND SPORTFISH MANAGEMENT ACTIVITIES. The introduction, establishment, and proliferation of nonnative fishes is considered the primary threat to the recovery of four Colorado River large-bodied endangered fishes. Unfortunately, in the upper Colorado River basin, despite years of significant effort, the nonnative threat remains largely uncontrolled. Only 13 of more than 50 fish species that now occur in the Upper Basin are native (Bezzerides and Bestgen 2002). Over the last 100 years, native fishes have decreased in range and abundance, while introduced fishes have concurrently become more widespread and abundant (▇▇▇▇▇▇▇ & ▇▇▇▇ 1989, ▇▇▇▇▇▇▇▇ et al. 1994; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014). An increasing body of evidence characterizes the negative interactions of nonnative fishes with the endangered fishes (▇▇▇▇▇▇▇ & ▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇ et al. 1998; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014), including predation and competition. Direct evidence of predation includes native fishes obtained from stomach contents of nonnative fishes (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014) and by visual observation of predation. Other means by which nonnative fishes may adversely affect native fishes are by competition for food and niche space. Warm water game fish, primarily stocked in reservoirs for recreational purposes, are thought to have the greatest adverse effect on endangered native fishes. Of those species, large-bodied predators are considered the most problematic – specifically centrarchids (smallmouth bass), esocids (northern pike), and percids (walleye). For example, during the 1990s, the Yampa River experienced a dramatic increase in northern pike and smallmouth bass numbers. Predation by these two piscivorous species wreaked havoc on the native fish community. Biologists documented significant declines of native fish densities in the Yampa River since that time (Bestgen et al.

REDUCE NEGATIVE IMPACTS OF NONNATIVE FISHES AND SPORTFISH MANAGEMENT ACTIVITIES. ‌ The introduction, establishment, and proliferation of nonnative fishes is are considered the primary threat to the recovery of four Colorado River large-bodied endangered fishes. Unfortunately, in the upper Colorado River basin, despite years of significant effort, the nonnative threat remains largely uncontrolled. Only 13 of more than 50 fish species that now occur in the Upper Basin are native (Bezzerides and Bestgen 2002). Over the last 100 years, native fishes have decreased in range and abundance, while introduced fishes have concurrently become more widespread and abundant (▇▇▇▇▇▇▇ & ▇▇▇▇ 1989, ▇▇▇▇▇▇▇▇ et al. 1994; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014). An increasing body of evidence characterizes the negative interactions of nonnative fishes with the endangered fishes (▇▇▇▇▇▇▇ & ▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇ et al. 1998; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014), including predation and competition. Direct evidence of predation includes native fish tags being detected in predatory fishes (▇▇▇▇▇▇▇▇▇ et al. 2017), native fishes obtained from stomach contents of nonnative fishes (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014) ), and by visual observation of predation. Other means by which nonnative fishes may adversely affect native fishes are by competition for food and niche space. Warm water game fish, primarily stocked in reservoirs for recreational purposes, are thought to have the greatest adverse effect on endangered native fishes. Of those species, large-bodied predators are considered the most problematic – specifically centrarchids (smallmouth bass), esocids (northern pike), and percids (walleye). For example, during the 1990s, the Yampa River experienced a dramatic increase in northern pike and smallmouth bass numbersnumbers in the 1990s and 2000s, respectively. Predation by these two piscivorous species wreaked havoc on the native fish community. Biologists documented significant declines of native fish densities in the Yampa River since that time (Bestgen et al. 2015). In studies on the Green River, researchers documented that young Colorado pikeminnow constituted 5% of the diet of northern pike, even though young Colorado pikeminnow made up a much smaller portion of the available food base in the river (▇▇▇▇▇ and ▇▇▇▇▇▇▇ 1996). Researchers estimated that a single northern pike could consume 100 or more young Colorado pikeminnow per year. In addition, northern pike are known to prey on large-bodied native fishes (▇▇▇▇▇▇▇▇ 2001, ▇▇▇▇▇▇▇ et al. 2005, ▇▇▇▇▇▇ and ▇▇▇▇▇▇ 2010) including adult Colorado pikeminnow, roundtail chub (Gila robusta), and ▇▇▇▇▇▇▇▇▇▇▇▇ and bluehead suckers. Recently, numbers of walleye have increased in the Green and lower Colorado rivers; ▇▇▇▇▇▇▇ and ▇▇▇▇▇ documented juvenile Colorado pikeminnow in the guts of nonnative walleye and reported a simultaneous decline in Colorado pikeminnow abundance in the lower Colorado River between 2010 and 2014 (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014). Burbot have been discovered in the Green River below Flaming Gorge Dam. ▇▇▇▇▇▇▇ and burbot pose a significant predatory and competitive threat to native and endangered fishes (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014, ▇▇▇▇▇▇▇▇ et al. 2011). Recovery Program activities related to nonnative fishes initially focused on identifying impacts/interactions and developing nonnative fish stocking procedures. Nonnative fish control strategies were developed to identify and prioritize options for controlling or removing nonnative fishes from river reaches occupied by the endangered fishes as well as other reaches that serve as production areas for nonnatives that subsequently disperse into occupied habitat (▇▇▇▇ and ▇▇▇▇▇▇▇▇ 1996; ▇▇▇▇▇▇▇ et al. 1996; ▇▇▇▇▇▇▇ and ▇▇▇▇▇▇ 1991). In February 2004, the Recovery Program adopted a nonnative fish management policy that addresses the process of identifying and implementing nonnative fish management actions needed to recover the endangered fishes (Upper Colorado River Endangered Fish Recovery Program 2004). Through 2009, emphasis was focused on the control activities identified in these strategies. Development of a new basin wide strategy for the management of nonnative aquatic species began in 2009, and was finalized in early 2014 (Nonnative Fish ad hoc Committee 2014). This strategy emphasizes prevention as a major component in efforts to control existing invasive impacts and to avoid similar impacts arising from existing or new species in additional locations within the Upper Basin. All nonnative fish control activities are evaluated for effectiveness annually. By thoroughly evaluating the smallmouth bass and northern pike control strategies in the Yampa River basin, the Larval Fish Lab at CSU provided the Program with guiding principles for nonnative removal in the entire basin. Specifically, both of these comprehensive evaluations indicate that the Recovery Program should focus on disrupting reproduction in the river and preventing immigration into river habitats, such as by limiting the escapement of these species from reservoirs. Disrupting in-river reproduction and preventing reservoir escapement are now the two key tenets of nonnative fish management. Limiting reproduction is accomplished through targeted removal of smallmouth bass during spawning (the Surge) and by netting northern pike in backwaters in the Yampa River. Landscape scale spawning disruptions of smallmouth bass via water management are also being considered (Bestgen and ▇▇▇▇ 2016; Bestgen 2018). Reservoir escapement is primarily prevented through installation of physical screens on outlets or channels and nets on spillways. Currently Starvation4, Elkhead, and Rifle Gap reservoirs, and Highline Lake, all have screened releases, while ▇▇▇▇▇▇▇ and Red Fleet reservoirs, and Lake Catamount, are planned for screening in the future. The States and the Service also have developed procedures for stocking of nonnative fishes in the Upper Basin (USFWS 1996a, 1996b). The procedures are designed to reduce the impact on native fishes from stocking of nonnative fishes in the Upper Basin and clarify the role of the States, the Service, and others in the review of stocking proposals. A cooperative agreement has been signed by the States and the Service implementing the Stocking Procedures. The Stocking Procedures were revised in 2009 (USFWS 2009) and the cooperative agreement was updated. The 2009 Stocking Procedures call for a review after 10-years, which is scheduled for 2019. In 2013, the Colorado Wildlife Commission updated changes to Colorado’s Wildlife Regulations that apply the provisions of the revised Stocking Procedures to the private aquaculture industry, in waters of both the Upper Colorado and San ▇▇▇▇ River. The provisions of the revised Stocking Procedures also are part of Utah’s stocking policy (including private aquaculture, which can only stock sterile salmonids without specific State review and approval). All private fish stocking in Wyoming also is subject to State review. Harvest regulations also play a key role in nonnative fish management. The Upper Basin States have liberalized bag and possession limits for the ‘worst of the worse’ predators (northern pike, smallmouth bass, walleye, and burbot). Utah and Wyoming have implemented must kill regulations for these species where appropriate. Colorado Parks and Wildlife has developed a “catch and keep” outreach strategy, paired with unlimited harvest and harvest incentives in regulation, as opposed to must kill regulations. The Colorado Parks and Wildlife Commission ratified unlimited harvest regulations for smallmouth bass and northern pike on the western slope, which took effect on April 1, 2016. The Recovery Program now implements a comprehensive strategy for nonnative fish management, focusing on in-river removal, reservoir escapement, and policy and outreach components. Over the past decade, the Recovery Program has committed millions of dollars and thousands of hours to removing these problematic predators from hundreds of miles of rivers in the upper Colorado River basin. What began over fifteen years ago as a pilot removal effort in 6 miles of the Yampa River now constitutes a basin-wide removal effort in more than 600 river miles, with some river reaches receiving up to 10 to 15 passes to disrupt spawning. In addition to this labor intensive effort, Recovery Program stakeholders are now preventing individuals from escaping reservoirs, implementing appropriate stocking and harvest policies, and conducting outreach on the problems of nonnative fish.

REDUCE NEGATIVE IMPACTS OF NONNATIVE FISHES AND SPORTFISH MANAGEMENT ACTIVITIES. ‌ The introduction, establishment, and proliferation of nonnative fishes is are considered the primary threat to the recovery of four Colorado River large-bodied endangered fishes. Unfortunately, in the upper Colorado River basin, despite years of significant effort, the nonnative threat remains largely uncontrolled. Only 13 of more than 50 fish species that now occur in the Upper Basin are native (Bezzerides and Bestgen 2002). Over the last 100 years, native fishes have decreased in range and abundance, while introduced fishes have concurrently become more widespread and abundant (▇▇▇▇▇▇▇ & ▇▇▇▇ 1989, ▇▇▇▇▇▇▇▇ et al. 1994; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014). An increasing body of evidence characterizes the negative interactions of nonnative fishes with the endangered fishes (▇▇▇▇▇▇▇ & ▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇ et al. 1998; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014), including predation and competition. Direct evidence of predation includes native fish tags being detected in predatory fishes (▇▇▇▇▇▇▇▇▇ et al. 2017), native fishes obtained from stomach contents of nonnative fishes (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014) ), and by visual observation of predation. Other means by which nonnative fishes may adversely affect native fishes are by competition for food and niche space. Warm water game fish, primarily stocked in reservoirs for recreational purposes, are thought to have the greatest adverse effect on endangered native fishes. Of those species, large-bodied predators are considered the most problematic – specifically centrarchids (smallmouth bass), esocids (northern pike), and percids (walleye). For example, during the 1990s, the Yampa River experienced a dramatic increase in northern pike and smallmouth bass numbers. Predation by these two piscivorous species wreaked havoc on the native fish community. Biologists documented significant declines of native fish densities in the Yampa River since that time (Bestgen et al. 2015). In studies on the Green River, researchers documented that young Colorado pikeminnow constituted 5% of the diet of northern pike, even though young Colorado pikeminnow made up a much smaller portion of the available food base in the river (▇▇▇▇▇ and ▇▇▇▇▇▇▇ 1996). Researchers estimated that a single northern pike could consume 100 or more young Colorado pikeminnow per year. In addition, northern pike are known to prey on large-bodied native fishes (▇▇▇▇▇▇▇▇ 2001, ▇▇▇▇▇▇▇ et al. 2005, ▇▇▇▇▇▇ and ▇▇▇▇▇▇ 2010) including adult Colorado pikeminnow, native roundtail chub (Gila robusta), ▇▇▇▇▇▇▇▇▇▇▇▇ and bluehead suckers, and may feed on humpback chubs in the Yampa River. More recently, ▇▇▇▇▇▇▇ and ▇▇▇▇▇ documented juvenile Colorado pikeminnow in the guts of nonnative walleye and reported a simultaneous decline in Colorado pikeminnow abundance in the lower Colorado River between 2010 and 2014, while walleye populations were increasing (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014). Recently, numbers of walleye have increased in the Green and lower Colorado rivers and burbot have been discovered in the Green River below Flaming Gorge Dam. Both of these species also pose a significant predatory and competitive threat to native and endangered fishes (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014, ▇▇▇▇▇▇▇▇ et al. 2011). Recovery Program activities related to nonnative fishes initially focused on identifying impacts/interactions and developing nonnative fish stocking procedures. Nonnative fish control strategies were developed to identify and prioritize options for controlling or removing nonnative fishes from river reaches occupied by the endangered fishes as well as other reaches that serve as production areas for nonnatives that subsequently disperse into occupied habitat (▇▇▇▇ and ▇▇▇▇▇▇▇▇ 1996; ▇▇▇▇▇▇▇ et al. 1996; ▇▇▇▇▇▇▇ and ▇▇▇▇▇▇ 1991). In February 2004, the Recovery Program adopted a nonnative fish management policy that addresses the process of identifying and implementing nonnative fish management actions needed to recover the endangered fishes (Upper Colorado River Endangered Fish Recovery Program 2004). Through 2009, emphasis was focused on the control activities identified in these strategies. Development of a new basin wide strategy for the management of nonnative aquatic species began in 2009, and was finalized in early 2014 (Nonnative Fish ad hoc Committee 2014). This strategy emphasizes prevention as a major component in efforts to control existing invasive impacts and to avoid similar impacts arising from existing or new species in additional locations within the Upper Basin. All nonnative fish control activities are evaluated for effectiveness annually. By thoroughly evaluating the smallmouth bass and northern pike control strategies in the Yampa River basin, the Larval Fish Lab at CSU provided the Program with guiding principles for nonnative removal in the entire basin. Specifically, both of these comprehensive evaluations indicate that the Recovery Program should focus on disrupting reproduction in the river and preventing immigration into river habitats, such as by limiting the escapement of these species from reservoirs. Disrupting in-river reproduction and preventing reservoir escapement are now the two key tenets of nonnative fish management. Limiting reproduction is accomplished through targeted removal of smallmouth bass during the spawn (the Surge) and by netting northern pike in backwaters in the Yampa River. Landscape scale spawning disruptions of smallmouth bass via water management are also being considered (Bestgen and ▇▇▇▇ 2016). Reservoir escapement is primarily prevented through installation of physical screens on outlets or channels and nets on spillways. Currently Starvation3, Elkhead and Rifle Gap Reservoirs, and Highline Lake, all have screened releases, while ▇▇▇▇▇▇▇ and Red Fleet Reservoirs, and Lake Catamount, are planned for screening in the future. The States and the Service also have developed procedures for stocking of nonnative fishes in the Upper Basin (USFWS 1996a, 1996b). The procedures are designed to reduce the impact on native fishes from stocking of nonnative fishes in the Upper Basin and clarify the role of the States, the Service, and others in the review of stocking proposals. A cooperative agreement has been signed by the States and the Service implementing the Stocking Procedures. The Stocking Procedures were revised in 2009 (USFWS 2009) and the cooperative agreement was updated. In 2013, the Colorado Wildlife Commission updated changes to Colorado’s Wildlife Regulations that apply the provisions of the revised Stocking Procedures to the private aquaculture industry, in waters of both the Upper Colorado and San ▇▇▇▇ River. The provisions of the revised Stocking Procedures also are part of Utah’s stocking policy (including private aquaculture, which can only stock sterile salmonids without specific State review and approval). All private fish stocking in Wyoming also is subject to State review. Harvest regulations also play a key role in nonnative fish management. The Upper Basin States have liberalized bag and possession limits for the ‘worst of the worse’ predators (northern pike, smallmouth bass, walleye, and burbot). Utah and Wyoming have implemented must kill regulations for these species where appropriate. Colorado Parks and Wildlife has developed a “catch and keep” outreach strategy, paired with unlimited harvest and harvest incentives in regulation, as opposed to must kill regulations. The Colorado Wildlife Commission ratified unlimited harvest regulations for smallmouth bass and northern pike on the western slope, which took effect on April 1, 2016.

REDUCE NEGATIVE IMPACTS OF NONNATIVE FISHES AND SPORTFISH MANAGEMENT ACTIVITIES. The introduction, establishment, and proliferation of nonnative fishes is are considered the primary threat to the recovery of four Colorado River large-bodied endangered fishes. Unfortunately, in the upper Colorado River basin, despite years of significant effort, the nonnative threat remains largely uncontrolled. Only 13 of more than 50 fish species that now occur in the Upper Basin are native (Bezzerides and Bestgen 2002). Over the last 100 years, native fishes have decreased in range and abundance, while introduced fishes have concurrently become more widespread and abundant (▇▇▇▇▇▇▇ & ▇▇▇▇ 1989, ▇▇▇▇▇▇▇▇ et al. 1994; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014). An increasing body of evidence characterizes the negative interactions of nonnative fishes with the endangered fishes (▇▇▇▇▇▇▇ & ▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇ et al. 1998; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014), including predation and competition. Direct evidence of predation includes native fishes obtained from stomach contents of nonnative fishes (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014) and by visual observation of predation. Other means by which nonnative fishes may adversely affect native fishes are by competition for food and niche space. Warm water game fish, primarily stocked in reservoirs for recreational purposes, are thought to have the greatest adverse effect on endangered native fishes. Of those species, large-bodied predators are considered the most problematic – specifically centrarchids (smallmouth bass), esocids (northern pike), and percids (walleye). For example, during the 1990s, the Yampa River experienced a dramatic increase in northern pike and smallmouth bass numbers. Predation by these two piscivorous species wreaked havoc on the native fish community. Biologists documented significant declines of native fish densities in the Yampa River since that time (Bestgen et al. 2015). In studies on the Green River, researchers documented that young Colorado pikeminnow constituted 5% of the diet of northern pike, even though young Colorado pikeminnow made up a much smaller portion of the available food base in the river (▇▇▇▇▇ and ▇▇▇▇▇▇▇ 1996). Researchers estimated that a single northern pike could consume 100 or more young Colorado pikeminnow per year. In addition, northern pike are known to prey on large-bodied native fishes (▇▇▇▇▇▇▇▇ 2001, ▇▇▇▇▇▇▇ et al. 2005, ▇▇▇▇▇▇ and ▇▇▇▇▇▇ 2010) including adult Colorado pikeminnow, native roundtail chub (Gila robusta), ▇▇▇▇▇▇▇▇▇▇▇▇ and bluehead suckers, and may feed on humpback chubs in the Yampa River. More recently, ▇▇▇▇▇▇▇ and ▇▇▇▇▇ documented juvenile Colorado pikeminnow in the guts of nonnative walleye and reported a simultaneous decline in Colorado pikeminnow abundance in the lower Colorado River between 2010 and 2014, while walleye populations were increasing (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014). Recently, numbers of walleye have increased in the Green and lower Colorado rivers and burbot have been discovered in the Green River below Flaming Gorge Dam. Both of these species also pose a significant predatory and competitive threat to native and endangered fishes (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014, ▇▇▇▇▇▇▇▇ et al. 2011). Recovery Program activities related to nonnative fishes initially focused on identifying impacts/interactions and developing nonnative fish stocking procedures. Nonnative fish control strategies were developed to identify and prioritize options for controlling or removing nonnative fishes from river reaches occupied by the endangered fishes as well as other reaches that serve as production areas for nonnatives that subsequently disperse into occupied habitat (▇▇▇▇ and ▇▇▇▇▇▇▇▇ 1996; ▇▇▇▇▇▇▇ et al. 1996; ▇▇▇▇▇▇▇ and ▇▇▇▇▇▇ 1991). In February 2004, the Recovery Program adopted a nonnative fish management policy that addresses the process of identifying and implementing nonnative fish management actions needed to recover the endangered fishes (Upper Colorado River Endangered Fish Recovery Program 2004). Through 2009, emphasis was focused on the control activities identified in these strategies. Development of a new basinwide strategy for the management of nonnative aquatic species began in 2009, and was finalized in early 2014 (Nonnative Fish ad hoc Committee 2014). This strategy emphasizes prevention as a major component in efforts to control existing invasive impacts and to avoid similar impacts arising from existing or new species in additional locations within the Upper Basin. All nonnative fish control activities are evaluated for effectiveness annually. By thoroughly evaluating the smallmouth bass and northern pike control strategies in the Yampa River basin, the Larval Fish Lab at CSU provided the Program with guiding principles for nonnative removal in the entire basin. Specifically, both of these comprehensive evaluations indicate that the Recovery Program should focus on disrupting reproduction in the river and preventing immigration into river habitats, such as by limiting the escapement of these species from reservoirs. Disrupting in-river reproduction and preventing reservoir escapement are now the two key tenets of nonnative fish management. Limiting reproduction is accomplished through targeted removal of smallmouth bass during the spawn (the Surge) and by netting northern pike in backwaters in the Yampa River. Landscape scale spawning disruptions of smallmouth bass via water management are also being considered (Bestgen and ▇▇▇▇ 2016). Reservoir escapement is primarily prevented through installation of physical screens on outlets or channels and nets on spillways. Currently Elkhead and Rifle Gap Reservoirs, and Highline Lake, all have screened releases, while ▇▇▇▇▇▇▇, Red Fleet and Starvation Reservoirs, and Lake Catamount, are planned for screening in the future. The States and the Service also have developed procedures for stocking of nonnative fishes in the Upper Basin (USFWS 1996a, 1996b). The procedures are designed to reduce the impact on native fishes from stocking of nonnative fishes in the Upper Basin and clarify the role of the States, the Service, and others in the review of stocking proposals. A cooperative agreement has been signed by the States and the Service implementing the Stocking Procedures. The Stocking Procedures were revised in 2009 (USFWS 2009) and the cooperative agreement was updated. In 2013, the Colorado Wildlife Commission updated changes to Colorado’s Wildlife Regulations that apply the provisions of the revised Stocking Procedures to the private aquaculture industry, in waters of both the Upper Colorado and San ▇▇▇▇ River. The provisions of the revised Stocking Procedures also are part of Utah’s stocking policy (including private aquaculture, which can only stock sterile salmonids without specific State review and approval). All private fish stocking in Wyoming also is subject to State review. Harvest regulations also play a key role in nonnative fish management. The Upper Basin States have liberalized bag and possession limits for the ‘worst of the worse’ predators (northern pike, smallmouth bass, walleye, and burbot). Utah and Wyoming have implemented must kill regulations for these species where appropriate. Colorado Parks and Wildlife has developed a “catch and keep” outreach strategy, paired with unlimited harvest and harvest incentives in regulation, as opposed to must kill regulations. The Colorado Wildlife Commission ratified unlimited harvest regulations for smallmouth bass and northern pike on the western slope which took effect on April 1, 2016. The Recovery Program now implements a comprehensive strategy for nonnative fish management, focusing on in-river removal, reservoir escapement, and policy and outreach components. Over the past decade, the Recovery Program has committed millions of dollars and thousands of hours to removing these problematic predators from hundreds of miles of rivers in the upper Colorado River basin. What began over fifteen years ago as a pilot removal effort in 6 miles of the Yampa River now constitutes a basin-wide removal effort in more than 600 river miles, with some river reaches receiving up to 10 to 15 passes to disrupt spawning. In addition to this labor intensive effort, Recovery Program stakeholders are now preventing individuals from escaping reservoirs, implementing appropriate stocking and harvest policies, and conducting outreach on the problems of nonnative fish.

REDUCE NEGATIVE IMPACTS OF NONNATIVE FISHES AND SPORTFISH MANAGEMENT ACTIVITIES. ‌ The introduction, establishment, and proliferation of nonnative fishes is are considered the primary remaining threat to the recovery of four Colorado River large-bodied endangered fishes. Unfortunately, in the upper Colorado River basin, despite years of significant effort, the nonnative threat remains largely uncontrolled. Only 13 of more than 50 fish species that now occur in the Upper Basin are native (Bezzerides and Bestgen 2002). Over the last 100 years, native fishes have decreased in range and abundance, while introduced fishes have concurrently become more widespread and abundant (▇▇▇▇▇▇▇ & ▇▇▇▇ 1989, ▇▇▇▇▇▇▇▇ et al. 1994; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014). An increasing body of evidence characterizes the negative interactions of nonnative fishes with the endangered fishes (▇▇▇▇▇▇▇ & ▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇▇ 1991; ▇▇▇▇▇▇▇ et al. 1998; ▇▇▇▇▇▇▇▇▇▇ & Bestgen 2002; ▇▇▇▇▇▇▇ & ▇▇▇▇▇ 2014), including predation and competition. Direct evidence of predation includes native fish tags being detected in predatory fishes (▇▇▇▇▇▇▇▇▇ et al. 2017), native fishes obtained from stomach contents of nonnative fishes (▇▇▇▇▇▇▇ and et al. 2015, ▇▇▇▇▇▇▇ 2014) et al. 2019)), and by visual observation of predation. Other means by which nonnative fishes may adversely affect native fishes are by competition for food and niche space. Despite years of significant effort and some notable success stories, nonnative fish remain a significant obstacle to recovery of endangered fish. Warm water game fish, primarily fish stocked in reservoirs for recreational purposes, are thought to have purposes subsequently escaped and established populations in the greatest adverse effect on endangered native fishesrivers. Of those species, large-bodied predators are considered the most problematic – specifically centrarchids (smallmouth bassbass [Micropterus dolomieu]), esocids (northern pikepike [Esox lucius]), and percids (walleyewalleye [Sander vitreus]). For example, during the 1990s, the Yampa River experienced a dramatic increase in northern pike and smallmouth bass numbersnumbers in the 1990s and 2000s, respectively. Predation by these two piscivorous species wreaked havoc on the native fish community. Biologists documented significant declines of native fish densities in the Yampa River since that time (Bestgen et al. 2015). Today, smallmouth bass populations are the dominant predator in the fish community of the middle Yampa River (upstream of Dinosaur National Monument), the middle Green River (between Whirlpool and Desolation Canyons), and the Grand Valley reach of the Colorado River. Smallmouth bass are increasing in density and range in the White River as well, threatening the strong native fish community in that tributary. Northern pike are primarily found in the Yampa River upstream of ▇▇▇▇▇, Colorado. However, adults are present downstream in the Yampa and Green rivers. Recently, numbers of walleye have increased in the lower Green and lower Colorado rivers and predation of juvenile pikeminnow has been documented (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014). Simultaneously, a decline in Colorado pikeminnow abundance was reported in the lower Colorado River between 2010 and 2015, which researchers attribute to a lack sufficient recruitment to offset adult mortality (▇▇▇▇▇▇▇ et al. 2020). Increasing density of walleye pose a significant predatory and competitive threat to native and endangered fishes (▇▇▇▇▇▇▇ and ▇▇▇▇▇ 2014, ▇▇▇▇▇▇▇▇ et al. 2011). Other species are also of concern to endangered fish recovery and are removed when encountered in endangered fish habitat. Largemouth bass, striped bass, green sunfish, and large (>450mm) channel catfish. can prey on endangered species . White sucker can hybridize with native suckers, reducing genetic diversity of native populations. Gizzard shad are a preferred food source for walleye and can support that nonnative predator. Recovery Program activities related to nonnative fishes initially focused on identifying impacts/interactions and developing nonnative fish stocking procedures. Nonnative fish control strategies were developed to identify and prioritize options for controlling or removing nonnative fishes from river reaches occupied by the endangered fishes as well as other reaches that serve as production areas for nonnatives that subsequently disperse into occupied habitat (▇▇▇▇ and ▇▇▇▇▇▇▇▇ 1996; ▇▇▇▇▇▇▇ et al. 1996; ▇▇▇▇▇▇▇ and ▇▇▇▇▇▇ 1991). In February 2004, the Recovery Program adopted a nonnative fish management policy that addresses the process of identifying and implementing nonnative fish management actions needed to recover the endangered fishes (Upper Colorado River Endangered Fish Recovery Program 2004). Through 2009, emphasis was focused on the control activities identified in these strategies. Development of a new basin wide strategy for the management of nonnative aquatic species began in 2009, and was finalized in early 2014 (Nonnative Fish ad hoc Committee 2014). This strategy emphasizes prevention as a major component in efforts to control existing invasive impacts and to avoid similar impacts arising from existing or new species in additional locations within the Upper Basin. Illegal introductions of nonnative fish have, and continue to, spread harmful species to new waters and often necessitate difficult and expensive treatments to remove, control, or contain them. All nonnative fish control activities are evaluated for effectiveness annually. By thoroughly evaluating the smallmouth bass and northern pike control strategies in the Yampa River basin, the Larval Fish Lab at Colorado State University (CSU) provided the Program with guiding principles for nonnative removal in the entire basin (Breton et al. 2014; ▇▇▇▇▇▇▇ et al. 2015). Specifically, both of these comprehensive evaluations indicate that the Recovery Program should focus on disrupting reproduction in the river and preventing immigration into river habitats, such as by limiting the escapement of these species from reservoirs. Disrupting in-river reproduction and preventing reservoir escapement are now the two key tenets of nonnative fish management. Limiting reproduction is accomplished through targeted removal of smallmouth bass during spawning (the Surge) and by netting northern pike in backwaters in the Yampa River. Landscape scale spawning disruptions of smallmouth bass via water management are also being considered (Bestgen and ▇▇▇▇ 2016; Bestgen 2018; ▇▇▇▇▇▇ et al. 2019; in review). Reservoir escapement is primarily prevented through installation of physical screens on outlets or channels and nets on spillways. Currently Starvation4, Elkhead, ▇▇▇▇▇▇▇, Red Fleet, and Rifle Gap reservoirs, and Highline Lake, all have screened releases, while ▇▇▇▇▇▇▇ Reservoir and Lake Catamount, are planned for screening in the future. Walleye and other species also move upstream from Lake ▇▇▇▇▇▇, but a solution to prevent their escapement has not been developed. The States and the Service also have developed procedures for stocking of nonnative fishes in the Upper Basin (USFWS 1996a, 1996b). The procedures are designed to reduce the impact on native fishes from stocking of nonnative fishes in the Upper Basin and clarify the role of the States, the Service, and others in the review of stocking proposals. A cooperative agreement has been signed by the States and the Service implementing the Stocking Procedures. The Stocking Procedures were revised in 2009 (USFWS 2009) and the cooperative agreement was updated. The 2009 Stocking Procedures call for a review after 10-years, which was scheduled for 2019. The Recovery Program will review the Stocking Procedures in coming years.