Fish Communities in Eelgrass, Oyster Culture, and Mudflat Habitats of North Humboldt Bay, California Final Report
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U.S. Fish and Wildlife Service Arcata Fisheries Technical Report Number TR2005-02 Fish Communities in Eelgrass, Oyster Culture, and Mudflat Habitats of North Humboldt Bay, California Final Report William D. Pinnix, Thomas A. Shaw, Kirsten C. Acker, and Nicholas J. Hetrick U.S. Fish and Wildlife Service Arcata Fish and Wildlife Office 1655 Heindon Road Arcata, CA 95521 (707) 882-7201 August 2005 Funding for this study was provided in part by the Humboldt Bay Harbor, Recreation and Conservation District (project # 11331-1937-1003) and NOAA Fisheries (project # 11331-1937-1010). Disclaimers Disclaimer: The mention of trade names or commercial products in this report does not constitute endorsement or recommendation for use by the Federal government. The U.S. Department of Interior prohibits discrimination in Department Federally Conducted Programs based on race, color, national origin, sex, age, or disability. If you believe that you have been discriminated against in any program, activity, or facility operated by the U.S. Fish and Wildlife Service or if you desire further information please write to: U.S. Department of the Interior Office of Equal Opportunity 1849 C. Street, N. W. Washington, D.C. 20240 Key words: fish, community structure, estuary, Humboldt Bay, eelgrass, oyster culture, mudflat The correct citation for this report is: Pinnix, W. D., T. A. Shaw, K. C. Acker and N. J. Hetrick. 2005. Fish communities in eelgrass, oyster culture, and mudflat habitats of North Humboldt Bay, California Final Report. U. S. Fish and Wildlife Service, Arcata Fish and Wildlife Office, Arcata Fisheries Technical Report Number TR2005-02, Arcata, California. ii Table of Contents Page List of Tables ..................................................................................................................... iv List of Figures.................................................................................................................... iv List of Appendices ............................................................................................................. vi Abstract............................................................................................................................... 1 Introduction......................................................................................................................... 2 Study Area .......................................................................................................................... 4 Methods............................................................................................................................... 4 Access to Sample Sites ................................................................................................... 4 Sampling Design............................................................................................................. 6 2003 and 2004............................................................................................................. 6 2005............................................................................................................................. 6 Sampling Gear ................................................................................................................ 7 Shrimp Trawl .............................................................................................................. 7 Beach Seine................................................................................................................. 7 Purse Seine.................................................................................................................. 8 Cast Net....................................................................................................................... 8 Fyke Net...................................................................................................................... 8 Minnow Trap .............................................................................................................. 8 Specimen Identification .............................................................................................. 8 Fish Community Analyses.............................................................................................. 8 Water Quality.................................................................................................................. 9 Sediment ......................................................................................................................... 9 Fyke Netting.................................................................................................................... 9 Results............................................................................................................................... 10 Sampling Gear Evaluation ............................................................................................ 10 Species Captured........................................................................................................... 10 Catch per Unit Effort .................................................................................................... 15 Shrimp trawl.............................................................................................................. 15 Fyke Net.................................................................................................................... 15 Fish Community Analyses............................................................................................ 17 Species Richness - Shrimp Trawl ............................................................................. 17 Species Richness – Fyke Net .................................................................................... 17 Diversity Indices – Shrimp Trawl............................................................................. 17 Diversity Indices – Fyke Net .................................................................................... 19 Water Quality................................................................................................................ 22 Sediment ....................................................................................................................... 23 Discussion......................................................................................................................... 24 Sampling Gear Effectiveness........................................................................................ 24 Baseline Fish Community............................................................................................. 25 iii Table of Contents, continued Page Fish Community Structure and Abundance.................................................................. 26 Summary........................................................................................................................... 27 Recommendations............................................................................................................. 28 Salmonid Life History and Habitat Use........................................................................ 28 South Bay, Central Bay, and North Bay Species Diversity Comparisons.................... 28 Acknowledgements........................................................................................................... 29 Literature Cited ................................................................................................................. 29 Appendices........................................................................................................................ 31 List of Tables Page 1. List of fish species collected in North Humboldt Bay using six different gear types between August 2003 and August 2005. Guild designations were determined from Gotshall et al. (1982). Lifestage represents the lifestage(s) captured during this study and n = number of individuals captured......................... 11 2. ANOVA results of Month x Habitat of shrimp trawl and fyke net day catches. Values listed are p–values, bold values indicate significance at the α=0.10 level........................................................................................................................... 16 3. ANOVA results of Day/Night x Habitat of shrimp trawl and fyke net catches. Values listed are p–values, bold values indicate significance at the α=0.10 level........................................................................................................................... 16 4. Percent fines in sediment samples collected from 20 study sites in North Humboldt Bay, California, from October 2003 to July 2004.................................... 24 List of Figures 1. Map of Humboldt Bay, California, showing three main areas within the bay, North Bay, Central Bay, and South Bay. .................................................................... 5 2. Major channels and locations of study sample sites in North Humboldt Bay, California..................................................................................................................... 6 3. Catch of English sole, shiner surfperch, and speckled sanddab by month from shrimp trawl samples conducted in North Humboldt Bay between August 2003 to August 2005. No sampling was conducted November 2004 through February 2005, and June 2005 through July 2005. ................................................... 12 4. Catch of bay pipefish, bay goby, and walleye surfperch by month from shrimp trawl samples conducted in North Humboldt