Arizona Game and Fish Department Research Branch Technical Report No. 12 Investigation of Techniques to Establish and Maintain Arctic Grayling and Apache Trout Lake Fisheries A Final Report Robert W. Clarkson and Richard J. Dreyer September 1992 Revised February 1996 Federal Aid in Sport Fish Restoration Project F-14-R TECHNIQUES TO ESTABLISH AND MAINTAIN ARCTIC GRAYLING AND APACHE TROUT LAKE FISHERIES GAME AND FISH COMMISSION Arthur R. Porter, Phoenix Nonie Johnson, Snowflake Michael M. Golightly, Flagstaff Herbert R. Guenther, Tacna Fred Belman, Tucson Director Duane L. Shroufe Deputy Director Thomas W. Spalding Assistant Directors Steven K. Ferrell Field Operations Bruce D. Taubert Wildlife Management Lee E. Perry Special Services David D. Daughtry Information & Education Suggested Citation: Clarkson, R. W. and R. J. Dreyer. 1996. Investigation of techniques to establish and maintain Arctic grayling and Apache trout lake fisheries. Ariz. Game and Fish Dep. Tech. Rep. 12, Phoenix. 71pp. ISSN 1052-7621 ISBN 0-917563-17-4 ARIZONA GAME & FISH DEPAR7MEN7; TECH. REP. 12 R. W CLARKSON AND R. J. DREyER 1996 TECHNIQUES TO ESTABLISH AND MAINTAIN ARCTIC GRAYLING AND APACHE TROUT LAKE FISHERIES CONTENTS Abstract 1 Introduction ..................................................................................................................................................................................... 1 Study Waters ..................................................................................................................................................................................... 2 Lee Valley Reservoir ............................................................................................................................................................ 2 Bear Canyon Lake .................................................................................................................................................................. 6 Methods .............................................................................................................................................................................................. 9 Fish Sampling and Population Estimates ...................................................................................................................... 9 Creel Surveys .......................................................................................................................................................................... 9 Water Quality ....................................................................................................................................................................... 10 Trophic Relationships ....................................................................................................................................................... 10 Equilibrium Yield ............................................................................................................................................................... 11 Results .............................................................................................................................................................................................. 13 Fish Stocking and Egg Take ............................................................................................................................................ 13 Creel Surveys ....................................................................................................................................................................... 14 Age and Growth .................................................................................................................................................................. 21 Population Estimates, Mortality, and Equilibrium Yield ..................................................................................... 28 Water Quality ....................................................................................................................................................................... 31 Trophic Relationships ....................................................................................................................................................... 35 Discussion ..................................................................................................................................................................................... 39 Age and Growth .................................................................................................................................................................. 39 Trophic Relationships ....................................................................................................................................................... 39 Angling and Equilibrium Yield ...................................................................................................................................... 40 Water Quality ....................................................................................................................................................................... 42 Management Options .................................................................................................................................................................. 43 Literature Cited ............................................................................................................................................................................. 45 Appendixes ..................................................................................................................................................................................... 47 R. W CLARKSON AND R. J. DREYER 1996 ARIZONA GAME & FISH DEPARTMENT, TECH. REP. 12 ill to* 0 s fk r-' ; 4 , AL° **. „ =,‘ 4410, 4N" 0 444'7* 4, 0Ik• 1 . 111 ' M1 kt a TECHNIQUES TO ESTABLISH AND MAINTAIN ARCTIC GRAYLING AND APACHE TROUT LAKE FISHERIES ACKNOWLEDGEMENTS We especially thank J. Novy and the Department Region I office for considerable logistic and office support during the field portion of this study. J. Walters, D. Kubly, R. Schweinsberg, J. deVos, J. Novy, S. Bryan, and others reviewed and improved earlier drafts of this document. V. Webb produced final layout and design, and helped with table formatting. This report is a result of studies undertaken with support provided by the Federal Aid in Sport Fish Restoration Act Project F-14-R of the Arizona Game and Fish Department. The Act is popularly known as the Dingell-Johnson Act after its Congressional sponsors. The Act provides for manufacturers' tax on fishing rods, reels, creels, and artificial baits, lures, and flies, with the revenue earmarked for the states and territories solely for projects that would enhance sportfishing restoration. Thus, sport fishermen are the contributors to a program that benefits everyone. In addition to the Department's Federal Aid funding, financial support for the project was provided by the U.S. Forest Service. This assistance greatly aided the collection of data reported herein. First edition publication costs of this report were paid by Dingell-Johnson funds. R. W CLARKSON AND R. J. DREYER 1996 ARIZONA GAME & FISH DEPARTMENT, TECH. REP. 12 V 7fiNq Investigation of Techniques to Establish and Maintain Arctic Grayling and Apache Trout Lake Fisheries Robert W. Clarkson and Richard J. Dreyer A bstract: We studied angler use, angler catch and harvest, and limnological and biological aspects of 2 high elevation lake fisheries in east-central Arizona from 1986-90 to evaluate a new "featured species" management concept. Two designated featured species, Arctic grayling (Thymallus arcticus) and Apache trout (Oncorhynchus apache), were stocked into Lee Valley Reservoir beginning in autumn 1986; Bear Canyon Lake received only Arctic grayling. Annual brook trout (Salvelinus fontinalis) stockings at both reservoirs ceased in 1986, and gear and bag restrictions were applied to both waters in 1987. Angler count surveys at Lee Valley Reservoir (14 surface hectares) indicated that angler use in 1987-90 dropped to approximately one-half the 1986 estimate of 20,000 angler hours, but remained within management-prescribed limits. Angler use at Bear Canyon Lake (26 hectares) was 3,700 hours in 1987, and 7,000 hours in 1988. Annual mean angler catch rates at Lee Valley Reservoir increased markedly over pre-study estimates to a maximum of 2.2 fish per hour in 1989, but harvest rates were near or below minimum management standards of 0.1 fish per hour. Mean annual catch rates at Bear Canyon Lake were less than 0.2 fish per hour; harvest was near zero. A large majority of anglers interviewed at Lee Valley Reservoir supported the new management direction and associated restrictions there, while only mild support for the new fishery was expressed by anglers at Bear Canyon Lake. These comparisons suggest that a put-grow-and-take Arctic grayling fishery at Bear Canyon Lake should be reconsidered. Analyses of benthic and planktonic food resources and salmonid feeding habits in Lee Valley Reservoir suggest that introduction of Arctic grayling altered zooplankton assemblage structure, and according to the trophic cascade hypothesis, possibly nutrient cycling and primary production (not measured). Alternatively, adverse physical-chemical conditions (high pH, low winter dissolved oxygen levels) associated with eutrophication of the reservoir may have influenced the observed