HISTORIC EXAMINATION OF THE CHANGES IN DIADROMOUS FISH POPULATIONS AND POTENTIAL ANTHROPOGENIC STRESSORS IN THE AVON RIVER WATERSHED, NOVA SCOTIA By Lisa A. Isaacman Submitted in partial fulfillment of the requirements for the degree of Master of Environmental Studies at Dalhousie University Halifax, Nova Scotia June 2005 © Copyright by Lisa A. Isaacman, 2005 DALHOUSIE UNIVERSITY SCHOOL FOR RESOURCE AND ENVIRONMENTAL STUDIES The undersigned hereby certify that they have read and recommend to the Faculty of Graduate Studies for acceptance a thesis entitled “Historic Examination of the Changes in Diadromous Fish Populations and Potential Anthropogenic Stressors in the Avon River Watershed, Nova Scotia” by Lisa A. Isaacman in partial fulfillment of the requirements for the degree of Master of Environmental Studies. Dated: June 23, 2005 Supervisor: ________________________________________________ Dr. Karen Beazley Associate Professor School for Resource and Environmental Studies Dalhousie University Committee Members: ________________________________________________ Dr. Peter Tyedmers Assistant Professor School for Resource and Environmental Studies Dalhousie University ________________________________________________ Dr. Mike Brylinsky Acting Director Acadian Centre for Estuarine Research Acadia University External Reader: ________________________________________________ Rod Bradford Diadromous Assessment/Species at Risk Biologist Department of Fisheries and Oceans ii DALHOUSIE UNIVERSITY DATE: June 23, 2005 AUTHOR: Lisa A. Isaacman TITLE: HISTORIC EXAMINATION OF THE CHANGES IN DIADROMOUS FISH POPULATIONS AND POTENTIAL ANTHROPOGENIC STRESSORS IN THE AVON RIVER WATERSHED, NOVA SCOTIA DEPARTMENT OR SCHOOL: School for Resource and Environmental Studies DEGREE: MES CONVOCATION: October YEAR: 2005 Permission is herewith granted to Dalhousie University to circulate and to have copied for non-commercial purposes, at its discretion, the above title upon the request of individuals or institutions. ________________________ Signature of Author The author reserves other publication rights, and neither the thesis nor extensive extracts from it may be printed or otherwise reproduced without the author’s written permission. The author attests that permission has been obtained for the use of any copyrighted material appearing in the thesis (other than the brief excerpts requiring only proper acknowledgement in scholarly writing), and that all such use is clearly acknowledged. iii Table of Contents List of Tables ................................................................................................................... vii List of Figures ................................................................................................................. viii Abstract .............................................................................................................................. ix List of Abbreviations ......................................................................................................... x Acknowledgements ........................................................................................................... xi Chapter 1: Introduction ................................................................................................... 1 1.1 Goal and Objectives ................................................................................................... 2 1.2 Description of the Study Area .................................................................................... 4 Chapter 2: Overview of Diadromous Species in the Minas Basin ................................ 8 2.1 Ecological Importance of Diadromous Fish Populations .......................................... 8 2.2 Diadromy in the Minas Basin/Bay of Fundy ............................................................. 9 2.3 Species Profiles ........................................................................................................ 11 2.3.1 Atlantic Salmon ................................................................................................ 11 2.3.2 Sea-Run Brook Trout (Sea-Trout) .................................................................... 12 2.3.3 Alewife and Blueback Herring (Gaspereau) ..................................................... 12 2.3.4 Rainbow Smelt .................................................................................................. 13 2.3.5 American Shad .................................................................................................. 13 2.3.6 Striped Bass ...................................................................................................... 14 2.3.7 Atlantic Sturgeon .............................................................................................. 15 2.3.8 Atlantic Tomcod ............................................................................................... 16 2.3.9 Sea Lamprey ..................................................................................................... 16 2.3.10 American Eel .................................................................................................. 17 2.4 Sensitivity of Diadromous Fishes to Human-Induced Threats ................................ 17 2.5 Status of Diadromous Species in the Bay of Fundy................................................. 19 Chapter 3: Methods ........................................................................................................ 21 3.1 Data Collection and Sources .................................................................................... 21 3.1.1 Key Informant Interviews ................................................................................. 23 3.1.2 Written Records ................................................................................................ 26 3.1.3 Fish Surveys ...................................................................................................... 27 iv 3.1.4 Fisheries Catch Data ......................................................................................... 28 3.1.5 Museum of Natural History Specimen Collections .......................................... 28 3.2 Data Synthesis .......................................................................................................... 28 3.3 Ethical Considerations ............................................................................................. 30 Chapter 4: Diadromous Fish in the Avon River Watershed ....................................... 31 4.1 Habitat ...................................................................................................................... 31 4.2 Status of Diadromous Fish ....................................................................................... 32 4.2.1 General Status of Fish prior to the Early 19th Century...................................... 32 4.2.2 Atlantic Salmon ................................................................................................ 33 4.2.3 Gaspereau (Alewife and Blueback Herring) ..................................................... 37 4.2.4 Rainbow Smelt .................................................................................................. 39 4.2.5 Sea-Run Brook Trout (Sea-Trout) .................................................................... 40 4.2.6 American Eel .................................................................................................... 42 4.2.7 American Shad .................................................................................................. 43 4.2.8 Striped Bass ...................................................................................................... 44 4.2.9 Atlantic Sturgeon .............................................................................................. 46 4.2.10 Atlantic Tomcod ............................................................................................. 47 4.2.11 Sea Lamprey ................................................................................................... 47 4.2.12 Other Facultatively Anadromous Species ....................................................... 48 4.3 Summary .................................................................................................................. 48 Chapter 5: Historical Overview of Potential Human-Induced Stressors .................. 52 5.1 Habitat Degradation and Loss .................................................................................. 52 5.1.1 Types of Threats to Habitat ............................................................................... 53 5.1.1.1 Water Quality Degradation ........................................................................ 53 5.1.1.2 Deforestation and Riparian Cover Changes ............................................... 55 5.1.1.3 Human-Made Barriers ............................................................................... 56 5.1.2 History of Habitat Loss and Degradation in the Avon River Watershed.......... 58 5.1.2.1 Dykes ......................................................................................................... 58 5.1.2.2 Agriculture, Forestry and Residential Development.................................. 59 5.1.2.3 Point Sources of Water Pollution ............................................................... 61 5.1.2.4 Mill-Dams .................................................................................................. 62 5.1.2.5 Hydro Power Generation ..........................................................................