Appendix E: Biological Resources Technical Report Coast Seafoods Company Humboldt Bay Harbor District Draft EIR Appendices October 2015 Biological Resources Impact Analysis for Coast Seafoods Company, Humboldt Bay Shellfish Aquaculture: Permit Renewal and Expansion Project Prepared for: Coast Seafoods Company/Pacific Seafoods 25 Waterfront Drive Eureka, CA 95501 Attn: Greg Dale Authored by: Chris Cziesla, Marlene Meaders, Phil Bloch, Mike McDowell, Ruth Park, Grant Novak, and Kerrie McArthur Confluence Environmental Company October 23, 2015 146 N Canal St, Suite 111 • Seattle, WA 98103 • www.confenv.com Biological Resources Technical Report TABLE OF CONTENTS 1.0 Summary ..................................................................................................................................... 1 1.1 Overwater Structure ................................................................................................................... 2 1.2 Unstructured Habitat ................................................................................................................. 2 1.3 Eelgrass Habitat ......................................................................................................................... 3 1.4 Other Habitat Concerns .............................................................................................................. 3 1.5 Potential Impacts to Benthic Communities ................................................................................ 4 1.6 Special-Status Species and Commercially Important Species ..................................................... 5 2.0 Project Description ...................................................................................................................... 6 2.1 Project Background .................................................................................................................... 6 2.2 Project Characteristics ................................................................................................................ 6 2.3 Project Alternatives .................................................................................................................... 8 2.4 Culture Methods ....................................................................................................................... 10 3.0 Existing Conditions .................................................................................................................... 11 3.1 General Habitat Conditions in Humboldt Bay ........................................................................... 11 3.2 North Bay Habitats ................................................................................................................... 13 3.3 Ecological Communities ........................................................................................................... 13 3.3.1 Subtidal Community ......................................................................................................... 13 3.3.2 Intertidal Community ....................................................................................................... 15 3.4 Pertinent Laws and Regulations ............................................................................................... 15 3.5 Special Status Species and Commercially Important Species ....................................................17 3.5.1 Dungeness Crab ................................................................................................................ 20 3.5.2 Pacific Lamprey ................................................................................................................ 20 3.5.3 Green Sturgeon and White Sturgeon (Sturgeon) .............................................................. 21 3.5.4 Coho and Chinook Salmon, Steelhead Trout, and Coastal Cutthroat Trout (Salmonids) ... 22 3.5.5 Southern Eulachon, Longfin Smelt, and Pacific Herring (Forage Fish) .............................. 24 3.5.6 Rockfish and California Halibut (Groundfish) .................................................................... 25 3.5.7 California Sea Lions, Harbor Seals, and Harbor Porpoises (Marine Mammals) .................. 27 4.0 Impact Metrics and Definition of Significance ........................................................................... 29 4.1 Impact Metrics.......................................................................................................................... 29 4.2 Thresholds of Significance ........................................................................................................ 30 Page i Biological Resources Technical Report 5.0 Impact Analysis of the Proposed Project ................................................................................... 32 5.1 Conservation Measures ............................................................................................................ 32 5.2 Potential Impacts to Habitat..................................................................................................... 33 5.2.1 Overwater Structures ....................................................................................................... 33 5.2.2 Unstructured Habitat ........................................................................................................ 34 5.2.3 Eelgrass Habitat ............................................................................................................... 35 Eelgrass Density Reduction ....................................................................................................... 36 Natural Variation and Eelgrass Resiliency .................................................................................. 37 Trampling .................................................................................................................................. 38 Fragmentation .......................................................................................................................... 39 Floating Eelgrass Rafts and Wrack ............................................................................................. 40 Summary of Eelgrass Impacts ................................................................................................... 41 5.2.4 Sediment Distribution and Tidal Circulation ..................................................................... 41 5.2.5 Water Quality ................................................................................................................... 42 Nutrients and Turbidity ............................................................................................................. 42 Contaminants ............................................................................................................................ 44 5.2.6 Sediment Quality .............................................................................................................. 45 5.3 Potential Impacts to Benthic Communities .............................................................................. 46 5.3.1 Changes to Species Composition ...................................................................................... 46 5.3.2 Trampling Effects ............................................................................................................. 49 5.3.3 Introduction of Non-Indigenous Species and Fouling Organisms ...................................... 50 5.3.4 Establishment of Non-Native Bivalves .............................................................................. 53 5.4 Potential Impacts to Dungeness Crab ....................................................................................... 53 5.4.1 Human Disturbance .......................................................................................................... 54 5.4.2 Habitat Degradation or Alteration .................................................................................... 54 5.4.3 Reduction in Prey Resources ............................................................................................. 55 5.4.4 Obstructions to Access or Migration Corridors ................................................................. 55 5.5 Potential Impacts to Pacific Lamprey ....................................................................................... 55 5.5.1 Human Disturbance .......................................................................................................... 56 5.5.2 Habitat Degradation or Alteration .................................................................................... 56 5.5.3 Reduction in Prey Resources ............................................................................................. 56 Page ii Biological Resources Technical Report 5.5.4 Obstructions to Access or Migration Corridors ................................................................. 56 5.6 Potential Impacts to Sturgeon .................................................................................................. 56 5.6.1 Human Disturbance .......................................................................................................... 57 5.6.2 Habitat Degradation or Alteration .................................................................................... 59 5.6.3 Reduction in Prey Resources ............................................................................................. 59 5.6.4 Obstructions to Access or Migration Corridors ................................................................. 59