Preliminary Report: Stream Crossings and Arctic Grayling Conservation in the Athabasca River Basin
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Preliminary Report: Stream Crossings and Arctic Grayling Conservation in the Athabasca River Basin CONSERVATION REPORT SERIES The Alberta Conservation Association is a Delegated Administrative Organization under Alberta’s Wildlife Act. CONSERVATION REPORT SERIES 25% Post Consumer Fibre When separated, both the binding and paper in this document are recyclable Preliminary Report: Stream Crossings and Arctic Grayling Conservation in the Athabasca River Basin Laura MacPherson1 and Troy Furukawa2 1University of Alberta, Department of Renewable Resources 751 General Services Building Edmonton, Alberta T6G 2H1 2Alberta Conservation Association #101, 9 Chippewa Rd Sherwood Park, Alberta T8A 6J7 Report Editors PETER AKU GLENDA SAMUELSON Alberta Conservation Association 2123 Crocus Road NW #101, 9 Chippewa Rd Calgary AB T2L 0Z7 Sherwood Park AB T8A 6J7 Conservation Report Series Type Preliminary Report Disclaimer: This document is an independent report prepared by the Alberta Conservation Association. The authors are solely responsible for the interpretations of data and statements made within this report. Reproduction and Availability: This report and its contents may be reproduced in whole, or in part, provided that this title page is included with such reproduction and/or appropriate acknowledgements are provided to the authors and sponsors of this project. Suggested Citation: MacPherson, L., and T. Furukawa. 2010. Preliminary report: Stream crossings and Arctic Grayling conservation in the Athabasca River Basin. Produced by the Alberta Conservation Association, Sherwood Park, Alberta, Canada. 30 pp + App. Cover photo credit: David Fairless Digital copies of conservation reports can be obtained from: Alberta Conservation Association #101, 9 Chippewa Rd Sherwood Park AB T8A 6J7 Toll Free: 1‐877‐969‐9091 Tel: (780) 410‐1998 Fax: (780) 464‐0990 Email: info@ab‐conservation.com Website: www.ab‐conservation.com ii EXECUTIVE SUMMARY The ability to accurately estimate fish abundance allows fishery biologists and managers to monitor fish populations and formulate management strategies. Reliable fish population estimates are particularly important for species at risk, such as Arctic Grayling (Thymallus arcticus), where a lack of population information could result in inappropriately assigned management decisions. Given severe declines in Alberta Arctic Grayling populations, accurate population information is critical for fisheries managers. In our study of the wadeable tributary streams of the Athabasca River, we evaluated the overall field efficiency of egg kick surveys, angling and electrofishing methods in estimating Arctic Grayling populations. We assessed how stream characteristics and temporal variability influenced Arctic Grayling catch rates, and compared population estimates derived from mark‐recapture and three‐pass removal methods. In turn, this allowed us to estimate capture probability (q) for small young‐of‐year (≤110 mm) and large (>110 mm) Arctic Grayling using angling and electrofishing. Lastly, we evaluated habitat fragmentation at stream crossing sites (road bridges and culverts), and at a larger sub‐basin scale. Geographic Information System (GIS) analysis was used to assess sub‐basin characteristics. Our results indicate that angling and electrofishing should be used together in order to capture all Arctic Grayling size classes. In addition, unless water conductivities exceed 300 μS/cm, electrofishing should occur later in the summer (July 16 ‐ August 31) when catch rates are highest. Similarly, angling catch rates were highest in the late summer. A small sample size and low recapture of Arctic Grayling precluded us from drawing any definite conclusions about the accuracy of mark‐recapture and three‐pass removal abundance estimates. We were however, able to determine capture probability (q) by gear type and fish size class. Given our findings, we created a sampling flow diagram for common fisheries management objectives. We found no evidence that Arctic Grayling populations were fragmented at stream crossing sites or at a sub‐basin scale. Despite this, we believe Arctic Grayling populations are likely already too severely impacted by cumulative iii anthropogenic impacts, including road culverts, such that these relationships were no longer easily discernible. Key words: Arctic Grayling, Thymallus arcticus, mark‐recapture, three‐pass removal, habitat fragmentation, bridge, culvert, Athabasca River. iv ACKNOWLEDGEMENTS This project is a result of collaborative work between the Alberta Conservation Association (ACA), Alberta Sustainable Resource Development (ASRD) and the Master’s of Science work of Laura MacPherson at the University of Alberta, Department of Renewable Resources (U of A). A special thank you to the ACA for contributing and making a NSERC IPS grant possible for Laura MacPherson. Thank you to Stephen Spencer, Don Hildebrandt, Owen Watkins, Shannon Stambaugh (ASRD) and Sierra Sullivan (U of A) for all their hard work during field sampling. A special thank you to Stephen Spencer, David Park, Michael Sullivan (ASRD), Lee Foote (U of A), Peter Aku (ACA), and Cam Stevens (Golder Associates) for guidance in project design and sampling. Mike Rodtka (ACA) provided invaluable comments and additions to this report. v vi TABLE OF CONTENTS EXECUTIVE SUMMARY ............................................................................................. iii ACKNOWLEDGEMENTS ............................................................................................ v TABLE OF CONTENTS .............................................................................................. vii LIST OF FIGURES ....................................................................................................... viii LIST OF TABLES ........................................................................................................... ix LIST OF APPENDICES .................................................................................................. x 1.0 INTRODUCTION ............................................................................................... 1 1.1 General introduction ....................................................................................... 1 1.2 Study rationale ................................................................................................. 1 1.3 Study objectives ............................................................................................... 2 2.0 STUDY AREA ...................................................................................................... 2 3.0 MATERIALS AND METHODS ........................................................................ 4 3.1 Field sampling ................................................................................................. 4 3.2 Statistical analysis ........................................................................................... 7 4.0 RESULTS .............................................................................................................. 9 4.1 Sampling method field efficiency ................................................................. 9 4.2 Temporal variability and size selectivity ..................................................... 9 4.3 Stream habitat and water quality characteristics ..................................... 13 4.4 Mark‐recapture and three‐pass removal methods ................................... 15 4.5 Habitat fragmentation .................................................................................. 16 4.6 Overall sampling conclusions ..................................................................... 18 5.0 DISCUSSION ..................................................................................................... 19 5.1 Field efficiency ............................................................................................... 19 5.2 Seasonal and temporal variation by gear type ......................................... 19 5.3 Size selectivity by gear ................................................................................. 20 5.4 Stream habitat and water quality characteristics ..................................... 21 5.5 Mark‐recapture and three‐pass removal methods ................................... 21 5.6 Habitat fragmentation .................................................................................. 23 5.7 Overall sampling conclusions ..................................................................... 24 6.0 LITERATURE CITED ....................................................................................... 26 vii LIST OF FIGURES Figure 1. Map of Athabasca River Basin, 2008 and 2009 study sites. ......................... 3 Figure 2. Mean (+SE) abundance (number/km) of Arctic Grayling (ARGR) captured in Athabasca River tributary streams using electrofishing and angling during the summers of 2008 and 2009. .......................................... 11 Figure 3. Number of Arctic Grayling caught in 2008 and 2009 by angling and electrofishing in Athabasca River tributary streams .................................. 12 Figure 4. Linear regression relationship between angler catch rate (fish/angler‐ hour) of Arctic Grayling and dissolved oxygen (mg/L) in Athabasca River tributary streams, 2008 and 2009 ........................................................ 14 Figure 5. Third order polynomial regression relationship between the number of Arctic Grayling (ARGR) captured using electrofishing (fish/100s) and conductivity