Status of the eulachon Thaleichthys pacificus in Canada

.....................................................................................................2 RÉSUMÉ..........................................................................................................3 TABLE OF CONTENTS..................................................................................4 INTRODUCTION ............................................................................................7 OBJECTIVE 7 BACKGROUND: THE DEVELOPING AWARENESS AND CONCERN ABOUT EULACHONS 7 BIOLOGY: TAXONOMY, DISTRIBUTION AND HABITATS.....................9 THE TAXONOMIC STATUS AND GLOBAL DISTRIBUTION OF EULACHONS (FAMILY OSMERIDAE) 9 THE COMMON NAME: EULACHON, OOLIGAN, HOOLICHONS, CANDLE FISH, ETC. 10 DISTRIBUTION IN BRITISH COLUMBIA : NUMBERS AND LOCATIONS OF SPAWNING RIVERS 11 SPAWNING LOCATIONS WITHIN RIVERS 12 LOCATIONS AND PHYSICAL CHARACTERISTICS OF SPAWNING RIVERS 12 MARINE LARVAL SURVEYS AS INDICATORS OF EULACHON SPAWNING RIVERS 12 ANADROMY: MARINE VERSUS FRESHWATER HABITAT 13 HOMING: BIOLOGICAL IMPLICATIONS 13 DISTRIBUTION IN THE SEA : MARINE HABITATS AND OFFSHORE DISTRIBUTION 14 PROXIMATE ANALYSIS 14 AGE DETERMINATION 14 REPRODUCTIVE BIOLOGY.......................................................................15 AGE OF SEXUAL MATURATION AND POST-SPAWNING MORTALITY 15 SEX RATIOS AND RELATIVE SIZES OF THE SEXES 16 FECUNDITY 16 SPAWNING TIMES 17 Among-river variation............................................................................................................ 17 Within-river variation. ........................................................................................................... 18 LIFE HISTORY STAGES .............................................................................18 THE EGG STAGE 18 THE LARVAL STAGE 18 Larval eulachon distribution in BC........................................................................................ 18 Larval eulachon: relative abundance..................................................................................... 20 Larval eulachon depth distribution and capture avoidance .................................................. 20 Larval surveys as indicators of spawning origins.................................................................. 21 Larval survey information as contributions to the biology of eulachons............................... 21 THE JUVENILE STAGE: AGES 8 WEEKS 12 MONTHS 22 THE OCEANIC, SUB-ADULT AND ADULT STAGE 22 THE PRE-SPAWNING STAGE 23 THE SPAWNING STAGE 23 THE POST-SPAWNING STAGE 23