FISHERY

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The Lees Ferry Rainbow Trout Fishery In 1964, the Lees Ferry tailrace on the Colorado River was given birth by the completion of Glen Canyon Dam, which impounded Lake Powell. Subsequent water releases from the bottom of Lake Powell changed the once highly turbid, warm waters of the Colorado River into a constant cold (46-50°F), clear flowing river. Shortly after completion of the dam, the Arizona Game and Fish Department stocked rainbow trout (Oncorhynchus mykiss) in the 15-mile Lees Ferry reach and, in 1981, began to manage this section of river as a Blue Ribbon rainbow trout fishery. The trout began to flourish in the Lees Ferry reach from 1970-1985 when catches of rainbow trout above 10-pounds were not uncommon, and angler pressure was relatively low. In 1991, however, the Bureau of Reclamation implemented the Record of Decision flow regime, which consisted of higher minimum and more stable flows and allowed for increased trout reproduction and survival. Under these conditions, a huge population of trout developed causing individual fish growth rates to decline. Quite simply, there was a large number of fish competing for limited space and food items, resulting in a fishery where trout less than 14-in were dominant. In 2000, the Arizona Game and Fish Department began a long-term monitoring program sponsored by Grand Canyon Monitoring and Research Center to determine the effects of Glen Canyon Dam operation on the trout fishery at Lees Ferry and to make recommendations for improving this fishery. Since 2000, our data collection has shown an increase in the general health of all trout age classes (especially since 2002). This increase in fish health is usually associated with an increase in growth rates. There has been a marked increase in catch rates of young-of-the-year fish in recent years. With successful spawning and recruitment continuing to occur, fishing conditions in Lees Ferry are improving. [1] LTEMP Resource Goal for the Rainbow Trout Fishery Achieve a healthy high-quality recreational rainbow trout fishery in GCNRA and reduce or eliminate downstream trout migration consistent with NPS fish management and ESA compliance. Desired Future Condition for the Lees Ferry Trout Fishery A high quality trout fishery in GCNRA, as further described in the Recreation DFC that does not adversely affect the native aquatic community in GCNP. • Minimize emigration of non-native fish from the Lees Ferry reach in Glen Canyon National Recreation Area to downstream locations. • Minimize emigration of non-native warm water fish to the mainstem Colorado River.

Rainbow Trout	Brown Trout

Updates [2] [3] [4] [5] [6] [7] [8] [9] [10] 2014 Collapse of the Lees Ferry Rainbow Trout Fishery Data from a large-scale mark-recapture study was used in an open population model to determine the cause for long-term trends in growth and abundance of a Rainbow Trout Oncorhynchus mykiss population in the tailwater of Glen Canyon Dam, AZ. Reduced growth affected multiple life stages and processes causing negative feedbacks that regulated the abundance of the population, including: higher mortality of larger fish; lower rates of recruitment (young of year) in years when growth was reduced; and lower rates of sexual maturation the following year. High and steady flows during spring and summer of 2011 resulted in very large recruitment event. The population declined 10-fold by 2016 due a combination of lower recruitment and reduced survival of larger trout. Survival rates for trout ≥ 225 mm in 2014, 2015, and 2016 were 11%, 21%, and 22% lower than average survival rates between 2012 and 2013, respectively. Abundance at the end of the study would have been three- to five-fold higher had survival rates for larger trout remained at the elevated levels estimated for 2012 and 2013. Growth declined between 2012 and 2014 owing to reduced prey availability, which led to very poor fish condition by fall of 2014 (~0.9-0.95). Poor condition in turn resulted in low survival rates of larger fish during fall of 2014 and winter of 2015, which contributed to the population collapse. In Glen Canyon, large recruitment events driven by high flows can lead to increases in the population that cannot be sustained due to limitations in prey supply. In the absence of being able to regulate prey supply, flows which reduce the probability of large recruitment events can be used to avoid boom-and-bust population cycles. Our study demonstrates that mark-recapture is a very informative approach for understanding the dynamics of tailwater trout populations. [11]

Links and Information Lees Ferry Anglers / Cliff Dwellers Lodge A local perspective on the Lees Ferry trout fishery by Terry Gunn, owner of Lees Ferry Anglers and Cliff Dwellers Lodge Lees Ferry Fishing Report AZGFD: Managing for Blue Ribbon Rainbow Trout at Lee's Ferry GCDAMP: Lees Ferry Recreational Trout Fishery Management Recommendations State of Arizona Lees Ferry Fish Management Plan 2013 National Park Service Comprehensive Fisheries Management Plan 2016 Fish Protocol Evaluation Panel (PEP) Related Pages The Trout Ad Hoc Group Page Brown Trout Page Whirling Disease Page Humpback Chub Page Aquatic Foodbase Page Water Quality Page Nutrients Page Rainbow Trout Projects Trout Management Flows (TMFs) Trout Reproductive and Growth Demographics (TRGD) Natal Origins Project (NO) Spring and Fall Lees Ferry Trout Monitoring and CREEL surveys Rainbow Trout Early Life Stage Study (RTELSS) Rainbow trout / humpback chub predation studies Trout Reduction Efforts Trout Stocking Bioenergetics Studies Rainbow Trout Individual Based Modeling (IBM) AZGFD Lees Ferry Rainbow Trout Fishery Annual Reports Status of the Lees Ferry Rainbow Trout Fishery 2017 Annual Report Presentations and Papers 2018 Grand Canyon flood fattened fish, but it's not all good news on the Colorado River Dibble et al., 2018, Warm water temperatures and shifts in seasonality increase trout recruitment but only moderately decrease adult size in western North American tailwaters: Environmental Biology of Fishes Compliance Status for Stocking in Glen Canyon PPT Letter from Governor Val Panteah, Sr.'s Statement on Proposed Stocking of Rainbow Trout at Lees Ferry by Arizona Game and Fish Department to the AMWG dated February 14, 2018 Turbidity as a management tool to constrain Rainbow Trout downstream of the Paria River PPT Effects of HFEs on Growth and Population Dynamics of Rainbow Trout in Glen Canyon and Mable Canyon PPT 2017 Korman et al., 2017, Trends in Rainbow Trout Recruitment, Abundance, Survival, and Growth during a Boom-and-Bust Cycle in a Tailwater Fishery, TAFS Dzul et al., 2017, Estimating disperser abundance using open population models that incorporate data from continuous detection PIT arrays, CJFAS Korman et al. 2017. Effects of environmental covariates and density on the catchability of fish populations and interpretation of catch per unit effort trends: Fisheries Research Lees Ferry Trout Fishery Status and PPT Lees Ferry Long Term Monitoring PPT Boom-and-Bust Cycles in the Population of Rainbow Trout in Glen Canyon and Effect of Fall High Flow Experiments PPT 2016 Grand Canyon Monitoring and Research Center Science Updates (BO Compliance, Trout Updates, Green Sunfish, Fisheries PEP, Partners in Science) Bair et al. 2016 Economic Value of Angling on the Colorado River at Lees Ferry: Using Secondary Data to Estimate the Influence of Seasonality: North American Journal of Fisheries Management, no. 6, vo. 36, p. 1229-1239, Grand Canyon Monitoring and Research Center Science Updates (BO Compliance, Trout Updates, Green Sunfish, Fisheries PEP, Partners in Science) Current Status of the Lees Ferry Fishery - Spring 2016 Lees Ferry Recreational Trout Fishery Management Recommendations: The Voice of Lees Ferry Recreational Anglers, Guides, and Businesses Memo from Scott VanderKooi to TWG Chair Dated 12/9/15, Subject: Technical Review of the Lees Ferry Recreational Trout Fishery Management recommendations Long-Term Monitoring of the Lees Ferry Fishery: Update Economic value of angling on the Colorado River at Lees Ferry: Using secondary data to estimate the influence of seasonality 2015 Dibble et al. 2015. Flow management and fish density regulate salmonid recruitment and adult size in tailwaters across western North America Lees Ferry Recreational Trout Fishery Management Recommendations: The Voice of Lees Ferry Recreational Anglers, Guides, and Businesses GCMRC Science Update - Trout GCMRC review of the Lees Ferry Anglers Trout Fishery Recommendations Management Prescription Mercury levels in Glen Canyon trout Potential Application of an Individual-Based Model to the Glen Canyon Glen Canyon Tailwater Fishery “Integrating Fish and Channel Mapping State of the Fishery Lees Ferry and Lees Ferry and Marble Canyon Rainbow Trout Update Lees Ferry Recreational Trout Fishery Lees Ferry Management Plan Update and handout 2014 Modeling Long Term Effects of HFEs on Trout and HBC Fisheries Update Context and Comparison: Status of Tailwater Fisheries in the Western United States 2013 GCMRC Update - Status of Resources and Sediment Conditions Science Update: Fisheries GCMRC Science Update on Sediment and Fisheries Rainbow trout monitoring update Grand Canyon Rainbow Trout 2012 Monitoring Results Effects of Recent Flow Events on the Juvenile Rainbow Trout Population in Lees Ferry 2012 Grand Canyon Monitoring and Research Updates GCMRC Updates and Sediment Update PPT Update on Native and Non-Native Fish Populations PPT GCMRC Updates and PPT AIF: Grand Canyon National Park Fishery Management Process and PPT 2011 Annual Report - Lees Ferry, Creel, and Mainstem Monitoring Salmonid Status and Trends. USGS Scientific Investigations Report 2011–5015 SSQ-1-4 2011 The Effects of Glen Canyon Dam Operations on Early Life Stages of Rainbow Trout in the Colorado River. USGS Fact Sheet Status and Trends of the Rainbow Trout Population in the Lees Ferry Reach of the Colorado River downstream from Glen Canyon Dam, Arizona, 1991–2009 2010 Effects of High-Flow Experiments from Glen Canyon Dam on Abundance, Growth, and Survival Rates of Early Life Stages of Rainbow Trout in the Lees Ferry Reach of the Colorado River. USGS Open–File Report 2010–1034 Rainbow Trout Abundance in the LCR Reach 2009 AIF: Grand Canyon Monitoring and Research Center (GCMRC) Update AIF: Lees Ferry Trout Fishery Group Update Grand Canyon Monitoring and Research Center updates by Program Managers Preliminary data update on AGFD Mainstem Colorado River fish monitoring Effects of Hydropeaking on Nearshore Habitat Use and Growth of Age-0 Rainbow Trout in a Large Regulated River written by Josh Korman and Steve Campana Effects of Fish Size, Habitat, Flow, and Density on Capture Probabilities of Age-0 Rainbow Trout Estimated from Electrofishing at Discrete Sites in a Large River written by Josh Korman, et. al Lees Ferry Fishing Report The river is a living creature. Just because you caught fish in a certain spot in years past, don’t think that you are going to experience the same success this year. Fishing is changing daily. It is our goal and desire that everyone have a great trip to the Ferry. Be sure to stop by the shop to see the flies that are currently working. The flies change on a daily basis and every day LFA guides let everyone at the shop know the top producing flies and how to use them. We are anxious to share this knowledge with you – even where to fish! There is an ongoing aquatic food base study that has taken place over the past couple of years. The purpose of this study is multifaceted and is studying the relationship of flows on food production, taking inventories of and monitoring populations of aquatic insects and invertebrates that live in the river and other very important aspects of the aquatic food base. I believe that this is by far the most important study that has ever been conducted on this river. Previously, hundreds of millions of dollars have been spent studying sediment while ignoring the aquatic food base and resource. Common sense dictates that fish, birds and animals do not live off of dirt or sand. The aquatic food base and habitat are the foundation for all that lives in the Colorado River. One of the long term goals of the food base study is to determine how to enhance the populations and production of aquatic insects in the river which will benefit native fish, trout, and migratory bird populations. This is a study and a goal that we can all embrace! Quagga mussels have become established in Lake Powell and we are now seeing some in the river below the dam. Their arrival in the river happened sooner than I expected. So far, there has not been a major infestation and there is some thought by experts that they will not become very well established in the river due to the current. Be aware and remember to dry waders and boots before using them in any other body of water. Also, all private boats should drain all water from the boat and live-wells as soon as you exit the river. We all need to do our part to limit the transport of this and all invasive species. Other Stuff Nutrients released from GCD and trout competition appear to have a bigger effect on growth than fall HFEs [12] The interaction of fish, foodbase, and temperature Fish occupying warmer water have higher metabolic demands than individuals in cooler water, and if these demands increase concurrently with a seasonal decline in prey availability, then growth rates may be reduced. [13] Vermillion: Highlights the passion the fishing community has for the Glen Canyon fishery and their love of not only the fishing experience but for the total experience. Arizona Game and Fish Wildlife Views article titled "Tight Lines at Lees Ferry". Published February 2012 Fishing Lees Ferry Visitor Use and Experience Visitor Experience as it relates to fisheries, include opportunities to fish for rainbow trout in GCNRA's Glen Canyon Reach, which has been referred to as Blue Ribbon by the State of Arizona, and to fish for rainbow and brown trout and a variety of non-native introduced fish species in the main stem Colorado River and some tributaries in GCNP. Most angling in GCNP occurs in or near Bright Angle Creek and Phantom Ranch, particularly in fall and spring (NPS 2006c). Definition of a Blue Ribbon fishery GCDAMP- Public Outreach- Lees Ferry Trout Fishery HISTORY In 1991 the Arizona Game and Fish stocked large trout instead of fingerling trout to maintain the Lees Ferry trout sport fishery (090711_Minority Report to TWG_FFF_Mark Steffen) Additional Links Bishop Study and Angler Preferences

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