Monthly Distribution and Catch Trends of Eulachon (Thaleichthys pacificus) from Juan de Fuca Strait to the Fraser River, British Columbia, October 2017 to June 2018 Lindsay V. Dealy and Vanessa R. Hodes Science Branch, Pacific Region Fisheries and Oceans Canada Pacific Biological Station Nanaimo, BC V9T 6N7 2019 Canadian Manuscript Report of Fisheries and Aquatic Sciences 3179 Canadian Manuscript Report of Fisheries and Aquatic Sciences Manuscript reports contain scientific and technical information that contributes to existing knowledge but which deals with national or regional problems. Distribution is restricted to institutions or individuals located in particular regions of Canada. However, no restriction is placed on subject matter, and the series reflects the broad interests and policies of Fisheries and Oceans Canada, namely, fisheries and aquatic sciences. Manuscript reports may be cited as full publications. The correct citation appears above the abstract of each report. 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Canadian Manuscript Report of Fisheries and Aquatic Science 3179 2019 MONTHLY DISTRIBUTION AND CATCH TRENDS OF EULACHON (Thaleichthys pacificus) FROM JUAN DE FUCA STRAIT TO THE FRASER RIVER, BRITISH COLUMBIA, OCTOBER 2017 TO JUNE 2018 by Lindsay V. Dealy and Vanessa R. Hodes Fisheries and Oceans Canada Science Branch, Pacific Region Pacific Biological Station 3190 Hammond Bay Road Nanaimo, British Columbia V9T 6N7 © Her Majesty the Queen in Right of Canada, 2019. Cat. No. Fs97-4/3179E-PDF ISBN 978-0-660-31188-3 ISSN 1488-5387 Correct citation for this publication: Dealy, L.V. and Hodes, V.R. 2019. Monthly distribution and catch trends of Eulachon (Thaleichthys pacificus) from Juan de Fuca Strait to the Fraser River, British Columbia, October 2017 to June 2018. Can. Manuscr. Rep. Fish. Aquat. Sci. 3179: viii + 39 p. ii TABLE OF CONTENTS LIST OF TABLES ............................................................................................................ iii LIST OF FIGURES ..........................................................................................................iv ABSTRACT .................................................................................................................... vii RÉSUMÉ ....................................................................................................................... viii INTRODUCTION ............................................................................................................. 1 METHODS ...................................................................................................................... 2 SURVEY DESIGN ....................................................................................................... 2 FISHING AND ENVIRONMENTAL DATA ................................................................... 3 CATCH RECORDING AND EULACHON CPUE ......................................................... 4 BIOLOGICAL SAMPLING ........................................................................................... 4 RESULTS ........................................................................................................................ 6 EULACHON CATCH AND CPUE ................................................................................ 6 BIOLOGICAL SAMPLING ........................................................................................... 8 ENVIRONMENTAL OBSERVATIONS ....................................................................... 21 DISCUSSION ................................................................................................................ 23 ACKNOWLEDGEMENTS ............................................................................................. 24 REFERENCES .............................................................................................................. 25 APPENDIX 1 ................................................................................................................. 27 APPENDIX 2 ................................................................................................................. 36 LIST OF TABLES Table 1. Descriptions of Eulachon gonadal development by sex and maturity stage. ..... 5 Table 2. Total number of sets, number of sets containing Eulachon, total catch of Eulachon (kg), mean CPUE (kg/hr), and standard error (SE) from bottom trawl surveys conducted in A1–Juan de Fuca, A2–Haro Strait, and A3–Fraser River from October 2017 to June 2018........................................................................................................... 7 Table 3. Number of Eulachon attributes recorded or collected during bottom trawl surveys conducted each month from October 2017 to June 2018 in Juan de Fuca and the Strait of Georgia. ....................................................................................................... 9 Table 4. Summary of length measurements including count, minimum length, 25th percentile (Q1), median length, mean length, 75th percentile (Q3), maximum length, and standard error (SE) of Eulachon sampled during bottom trawl surveys in A1–Juan de Fuca, A2–Haro Strait, and A3–Fraser River from October 2017 to June 2018. ....... 12 iii Table 5. Sexes assigned to Eulachon sampled during bottom trawl surveys in A1–Juan de Fuca, A2–Haro Strait, and A3–Fraser River from October 2017 to June 2018. Total males sampled: n=1,740; total females sampled: n=1,885; undetermined: n=181........ 13 Table 6. Standard length measurements of Eulachon (n=3,359) for each maturity stage assigned during bottom trawl sets in A1–Juan de Fuca, A2–Haro Strait, and A3–Fraser River from October 2017 to June 2018. Summary statistics include minimum length (min.), 25th percentile (Q1), median length, mean length, 75th percentile (Q3), maximum length (max.), standard error (SE), and count. Maturity stages are described in Table 1 (0-2 = immature, 3-4 = developing, 5 = mature (ripe), 6 = atypical). ............................. 16 Table 7. Number of Eulachon stomachs by stomach content category. Each stomach contained only one type of content. Eulachon stomachs (n=2,245) were sampled during bottom trawl sets in A1–Juan de Fuca, A2–Haro Strait, and A3–Fraser River from October 2017 to June 2018. .......................................................................................... 18 Table 8. Counts of Eulachon sampled for presence of teeth by category in A1–Juan de Fuca, A2–Haro Strait, and A3–Fraser River by month (January–June 2018). Categories: None=no teeth; TMB=teeth present on the top, tongue, and bottom of the mouth; TM=top and tongue only; TB=top and bottom only; MB=tongue and bottom only; M=tongue only; and T=top only. .................................................................................... 19 Table 9. Cumulative catch and species composition from bottom trawl surveys (n= 227 sets) conducted in Juan de Fuca Strait and Strait of Georgia from October 2017 to June 2018. ............................................................................................................................. 36 LIST OF FIGURES Figure 1. Study