Arctic Grayling (Thymallus Arcticus) in the Pembina River, Alberta
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Status and Distribution of Arctic Grayling (Thymallus arcticus) in the Pembina River, Alberta CCONSERVATIONONSERVATION RREPORTEPORT SSERIESERIES The Alberta Conservation Association is a Delegated Administrative Organization under Alberta’s Wildlife Act. CCONSERVATIONONSERVATION RREPORTEPORT SSERIESERIES 25% Post Consumer Fibre When separated, both the binding and paper in this document are recyclable Status and Distribution of Arctic grayling (Thymallus arcticus) in the Pembina River, Alberta Mike Blackburn and Craig F. Johnson Alberta Conservation Association, #203, Provincial Building, 111 – 54 Street, Edson, Alberta, Canada, T7E 1T2 Report Series Editor PETER AKU P.O. Box 40027 Baker Centre Postal Outlet Edmonton, AB, T5J 4M9 Conservation Report Series Type Data, Technical ISBN printed: 978‐0‐7785‐5407‐3 ISBN online: 978‐0‐7785‐5408‐0 Publication Number: T/122 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: Blackburn, M., and C.F. Johnson. 2004. Status and distribution of Arctic grayling (Thymallus arcticus) in the Pembina River, Alberta. Technical Report, T‐2004‐003, produced by Alberta Conservation Association, Edson, Alberta, Canada. 25 pp +App. Digital copies of this and other conservation reports can be obtained from: Alberta Conservation Association P.O. Box 40027, Baker Centre Postal Outlet Edmonton, AB, T5J 4M9 Toll Free: 1‐877‐969‐9091 Tel: (780) 427‐5192 Fax: (780) 422‐6441 Email: info@ab‐conservation.com Website: www.ab‐conservation.com i EXECUTIVE SUMMARY The Pembina River sub‐basin, found in the Athabasca River Drainage, supports the most southern, naturally occurring population of Arctic grayling in Alberta. Prior to the 1970’s, Arctic grayling were considered common throughout the mid to upper reaches of the Pembina River mainstem. However, since that time, surveys on the Pembina River mainstem suggest low numbers of this species. Consequently, the Alberta Conservation Association, in collaboration with the Alberta Sustainable Resource Development, conducted a study during the open water seasons of 2002 and 2003 to assess the present status and distribution of Arctic grayling in the Pembina River. The proposed study area included the Pembina River mainstem from the Lovett River confluence downstream to the Paddle River. After preliminary sampling in 2002, the study area was redefined in 2003 to include the Pembina River mainstem from the mouth of the Lovett River downstream to the Highway 16 river crossing at Evansburg. Species distribution, relative abundance, and population structure data were collected using float electrofishing, angling, and snorkelling. Quantitative habitat data were also collected including: wetted river widths, rooted river widths, and water temperature data collected continuously through time from several locations in the study area. All fish and habitat data were entered into Alberta Sustainable Resource Development’s provincial fisheries database: the Fisheries Management Information System. Over the two years, a total (combined float electrofishing, angling, and snorkelling) of 2817 fish were captured or observed in the Pembina River. Arctic grayling were rare, accounting for less than 2.5% of the recorded total. Forty‐six Arctic grayling were captured in 52.8 km and 591.7 minutes of electrofishing and 22.7 km and 56.5 hours of angling. An additional 22 Arctic grayling were observed during four snorkelling events for a total of 68 grayling. Arctic grayling float electrofishing and angling catch rates from the Pembina River were considerably lower than reported for other Alberta rivers. Angling accounted for 42 of the 46 Arctic grayling which were caught near a road access; 33 of the 42 angling captures were from one pool immediately downstream of a bridge crossing. ii The mean fork length of Arctic grayling captured was 213 mm (range = 115 ‐ 339 mm). Ninety‐five percent of the captured Arctic grayling were juveniles of either 1 or 2 years of age. Sampling was initiated during the spring and summer of 2002. Extremely low water conditions during both 2002 and 2003 prevented spring, summer, and fall re‐sampling of the float electrofishing sites. Although grayling were captured upstream from the confluence with Paddy Creek only, we were unable to describe Arctic grayling seasonal distribution. Low numbers of Arctic grayling captured or observed in two years of sampling, low electrofishing and angling catch rates, and a limited river distribution, suggests that Arctic grayling stocks in the Pembina River are probably collapsed. Key words: Alberta, Pembina River, Arctic grayling, distribution, abundance, size composition, float electrofishing, angling, snorkelling, age, size‐at‐age, catch rate. iii ACKNOWLEDGEMENTS This work was funded by the Alberta Conservation Association (ACA). In addition, the ACA received in‐kind support from Alberta Sustainable Resource Development, Fisheries Management Division in Edson, Hinton, and Stony Plain. Stephen Spencer, Area Fisheries Biologist, Fisheries Management Division in Stony Plain, and George Sterling, Area Fisheries Biologist, Fisheries Management Division in Edson provided critical review of the project design and of this report, and contributed to field data collection. Special thanks to Calvin McLeod, East Slopes Business Unit Leader, ACA; and Kevin Fitzsimmons, Fisheries Biologist, ACA, for critical review of this report. Christian Weik, Geographic Information System Analyst, Foothills Model Forest (Hinton, AB), provided assistance with generating the Pembina River profile data. Thanks to Rudy Hawryluk, Don Hildebrandt, Julie Hebert, Corey Rasmussen, James Milner, Norm Rodseth and Susan Parsons for their contributions to field data collection. iv TABLE OF CONTENTS EXECUTIVE SUMMARY.............................................................................................. ii ACKNOWLEDGEMENTS........................................................................................... iv TABLE OF CONTENTS ................................................................................................ v LIST OF FIGURES ......................................................................................................... vi LIST OF TABLES.......................................................................................................... vii LIST OF APPENDICES ..............................................................................................viii 1.0 INTRODUCTION.................................................................................................1 1.1 General introduction............................................................................................1 1.2 Study rationale ......................................................................................................2 1.3 Study objectives ....................................................................................................2 2.0 STUDY AREA .......................................................................................................3 3.0 MATERIALS AND METHODS..........................................................................5 3.1 Site selection ..........................................................................................................5 3.2 Site length ..............................................................................................................6 3.3 Fish capture and data collection.........................................................................6 3.4 Habitat data ...........................................................................................................7 3.5 Data management and analysis..........................................................................8 4.0 RESULTS................................................................................................................9 4.1 Electrofishing.......................................................................................................10 4.2 Angling.................................................................................................................12 4.3 Snorkelling...........................................................................................................13 4.4. Size distribution of Arctic grayling..................................................................14 4.5 Age composition of Arctic grayling.................................................................15 4.6 Distribution of Arctic grayling .........................................................................16 4.7 Water temperature data.....................................................................................17 5.0 DISCUSSION.......................................................................................................18 6.0 REFERENCES......................................................................................................21 7.0 APPENDIX ..........................................................................................................26 v LIST OF FIGURES Figure 1. Location of the 2002‐2003 Arctic grayling study sites on