Evaluation of Largemouth Bass Habitat, Population Structure, and Reproduction in the Upper Housatonic River, Massachusetts Prepared for: Prepared by: General Electric Company R2 Resource Consultants, Inc. 100 Woodlawn Avenue 15250 N.E. 95th Street Pittsfield, Massachusetts 01201 Redmond, Washington 98052 July 23, 2002 Evaluation of Largemouth Bass Habitat, Population Structure, and Reproduction in the Upper Housatonic River, Massachusetts Prepared for: General Electric Company Pittsfield, Massachusetts Prepared by: Emily S. Greenberg Dudley W. Reiser, Ph.D. Michael E. Loftus, Ph.D. Warren D. Coughlin R2 Resource Consultants, Inc. 15250 N.E. 95th St. Redmond, Washington. 98052 July 2002 General Electric Company Housatonic River Largemouth Bass CONTENTS EXECUTIVE SUMMARY.......................................................................................................... xiv 1. INTRODUCTION AND BACKGROUND...........................................................................1-1 1.1 STUDY CONTEXT..............................................................................................................1-2 1.2 OBJECTIVES......................................................................................................................1-6 1.3 REPORT OUTLINE .............................................................................................................1-7 2. DESCRIPTION OF STUDY AREA......................................................................................2-1 2.1 STUDY REACH..................................................................................................................2-1 2.2 INDEX REACH...................................................................................................................2-2 3. LARGEMOUTH BASS LIFE HISTORY .............................................................................3-1 3.1 RANGE .............................................................................................................................3-1 3.2 HABITAT PREFERENCE .....................................................................................................3-2 3.3 FLOW AND WATER LEVELS ..............................................................................................3-3 3.4 REPRODUCTION ................................................................................................................3-3 3.5 HATCHING SUCCESS.........................................................................................................3-4 3.6 TEMPERATURE .................................................................................................................3-6 3.7 PH....................................................................................................................................3-7 3.8 DISSOLVED OXYGEN ........................................................................................................3-7 3.9 FOOD RESOURCES ............................................................................................................3-8 3.10 MIGRATION AND LOCAL MOVEMENT .............................................................................3-9 3.11 GROWTH RATES ...........................................................................................................3-10 R2 Resource Consultants, Inc. iii July 2002 1291.07/Housatonic River Report_702 General Electric Company Housatonic River Largemouth Bass 3.12 MORTALITY..................................................................................................................3-11 3.13 POPULATION STRUCTURE AND ABUNDANCE ................................................................3-12 3.13.1 Proportional Stock Density..............................................................................3-13 3.13.2 Relative Weight ...............................................................................................3-15 3.13.3 Abundance .......................................................................................................3-16 4. METHODS.............................................................................................................................4-1 4.1 CANDIDATE REFERENCE STREAM ASSESSMENT ...............................................................4-2 4.2 AQUATIC HABITAT ASSESSMENT .....................................................................................4-4 4.2.1 Habitat Mapping ..................................................................................................4-4 4.2.2 Site-Specific Habitat Surveys ..............................................................................4-8 4.3 LARGEMOUTH BASS DISTRIBUTION, POPULATION STRUCTURE, AND GROWTH RATES...4-10 4.3.1 Adult and Juvenile Sampling.............................................................................4-10 4.3.1.1 Year 2000 Surveys ................................................................................4-12 4.3.1.2 Year 2001 Surveys ................................................................................4-14 4.3.2 Age and Growth.................................................................................................4-14 4.3.3 Proportional Stock Density................................................................................4-17 4.3.4 Relative Weight .................................................................................................4-17 4.3.5 Catch-Per-Unit-Effort ........................................................................................4-18 4.4 LARGEMOUTH BASS REPRODUCTION .............................................................................4-18 4.4.1 Year 2000 Surveys.............................................................................................4-19 4.4.2 Year 2001 Surveys.............................................................................................4-19 4.4.2.1 Nest and Brood Observations................................................................4-22 4.4.2.2 Larval and YOY Sampling....................................................................4-24 4.5 FISH COMMUNITY SURVEYS...........................................................................................4-26 4.6 ENVIRONMENTAL CONDITIONS MONITORING.................................................................4-26 4.6.1 Water Temperature ............................................................................................4-26 R2 Resource Consultants, Inc. iv July 2002 1291.07/Housatonic River Report_702 General Electric Company Housatonic River Largemouth Bass 4.6.2 Dissolved Oxygen..............................................................................................4-29 4.6.3 Cloud Cover.......................................................................................................4-30 4.6.4 Flow ...................................................................................................................4-30 5. RESULTS...............................................................................................................................5-1 5.1 AQUATIC HABITAT ASSESSMENT .....................................................................................5-1 5.2 LARGEMOUTH BASS DISTRIBUTION, POPULATION STRUCTURE, AND REPRODUCTION .......5-1 5.2.1 Largemouth Bass Distribution .............................................................................5-1 5.2.2 Largemouth Bass Population Structure................................................................5-5 5.2.2.1 Size Class Structure.................................................................................5-5 5.2.2.2 Age Structure...........................................................................................5-7 5.2.2.3 Proportional Stock Density ...................................................................5-10 5.2.2.4 Relative Weight.....................................................................................5-10 5.2.2.5 Young-of-Year Catch-Per-Unit-Effort ..................................................5-10 5.2.3 Largemouth Bass Reproduction.........................................................................5-14 5.2.3.1 Year 2000 Spawning and Larval Fish Surveys .....................................5-14 5.2.3.2 Year 2001 Spawning and Larval Fish Surveys .....................................5-14 5.2.4 Young-of-Year Growth Rates............................................................................5-21 5.2.4.1 Year 2000 Young-of-Year Growth Rates..............................................5-21 5.2.4.2 Year 2001 Young-of-Year Growth Rates..............................................5-23 5.3 FISH COMMUNITY STUDIES ............................................................................................5-28 5.3.1 Mainstem Surveys..............................................................................................5-30 5.3.2 East and West Branch and Tributary Surveys....................................................5-35 5.4 ENVIRONMENTAL CONDITIONS MONITORING.................................................................5-35 5.4.1 Water Temperature ............................................................................................5-35 5.4.2 Dissolved Oxygen..............................................................................................5-39 5.4.3 Flow ...................................................................................................................5-43 5.4.4 Cloud Cover.......................................................................................................5-45