NOAA Technical Memorandum NMFS-NWFSC-93 The 2005 U.S. West Coast Bottom Trawl Survey of Groundfish Resources off Washington, Oregon, and California: Estimates of Distribution, Abundance, and Length Composition July 2008 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service NOAA Technical Memorandum NMFS-NWFSC Series The Northwest Fisheries Science Center of the National Marine Fisheries Service, NOAA, uses the NOAA Techni- cal Memorandum NMFS-NWFSC series to issue scientific and technical publications. Manuscripts have been peer reviewed and edited. Documents published in this series may be cited in the scientific and technical literature. The NMFS-NWFSC Technical Memorandum series of the Northwest Fisheries Science Center continues the NMFS- F/NWC series established in 1970 by the Northwest & Alaska Fisheries Science Center, which has since been split into the Northwest Fisheries Science Center and the Alaska Fisheries Science Center. The NMFS-AFSC Techni- cal Memorandum series is now being used by the Alaska Fisheries Science Center. Reference throughout this document to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. This document should be referenced as follows: Keller, A.A., B.H. Horness, E.L. Fruh, V.H. Simon, V.J. Tuttle, K.L. Bosley, J.C. Buchanan, D.J. Kamikawa, and J.R. Wallace. 2008. The 2005 U.S. West Coast bottom trawl survey of groundfish resources off Washington, Ore- gon, and California: Estimates of distribution, abundance, and length composition. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-93, 136 p. NOAA Technical Memorandum NMFS-NWFSC-93 The 2005 U.S. West Coast Bottom Trawl Survey of Groundfish Resources off Washington, Oregon, and California: Estimates of Distribution, Abundance, and Length Composition Aimee A. Keller, Beth H. Horness, Erica L. Fruh, Victor H. Simon, Vanessa J. Tuttle, Keith L. Bosley, John C. Buchanan, Dan J. Kamikawa, and John R. Wallace Northwest Fisheries Science Center Fishery Resource Analysis and Monitoring Division 2725 Montlake Boulevard East Seattle, Washington 98112 July 2008 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Most NOAA Technical Memorandums NMFS-NWFSC are available online at the Northwest Fisheries Science Center web site (http://www.nwfsc.noaa.gov) Copies are also available from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone orders (1-800-553-6847) e-mail orders ([email protected]) ii Table of Contents List of Figures...............................................................................................................................................v List of Tables ...............................................................................................................................................ix Executive Summary.....................................................................................................................................xi Acknowledgments......................................................................................................................................xiii Introduction...................................................................................................................................................1 Survey Methods ............................................................................................................................................4 Survey Period and Sampling Area............................................................................................................4 Vessels and Sampling Gear ......................................................................................................................4 Trawl Station Allocation ..........................................................................................................................6 Trawl Operation Protocol .........................................................................................................................7 Sampling Procedures and Biological Data Collection..............................................................................9 Survey Analysis ..........................................................................................................................................10 Sensor Data.............................................................................................................................................10 Net Mensuration .....................................................................................................................................11 Area Estimates........................................................................................................................................12 Temperature............................................................................................................................................12 Relative Density and Biomass Estimates ...............................................................................................13 Results.........................................................................................................................................................14 Haul, Catch, and Biological Data ...........................................................................................................14 Temperature Data ...................................................................................................................................50 Relative Density and Distribution of Species.........................................................................................50 Biomass and Population Estimates.........................................................................................................87 Size Compositions ................................................................................................................................100 Weight-length Relationships ................................................................................................................130 Length-age Relations............................................................................................................................130 Analysis Approach and Data Requests.................................................................................................134 References.................................................................................................................................................135 iii iv List of Figures Figure 1. Map showing extent of the 2005 West Coast groundfish trawl survey and the locations of completed stations.........................................................................................................................................3 Figure 2. Detailed diagram of the NWFSC Aberdeen-style sampling trawl, including descriptions of dimensions, materials, mesh sizes, and mesh counts....................................................................................5 Figure 3. Footrope for the NWFSC Aberdeen-style sampling trawl composed of seven sections with an overall length of 104 feet. ........................................................................................................................6 Figure 4. Mean net width and height for trawls conducted as part of the 2005 West Coast groundfish trawl survey.................................................................................................................................................16 Figure 5. Near bottom temperature observed at the mouth of the net for each tow conducted during the 2005 West Coast groundfish trawl survey ............................................................................................51 Figure 6. Sea surface temperature observed at the start of each tow during the 2005 NWFSC West Coast groundfish trawl survey ....................................................................................................................52 Figure 7. Arrowtooth flounder distribution and relative abundance from the 2005 West Coast groundfish trawl survey. .............................................................................................................................58 Figure 8. Blackgill rockfish distribution and relative abundance from the 2005 West Coast groundfish trawl survey.................................................................................................................................................59 Figure 9. Bocaccio rockfish distribution and relative abundance from the 2005 West Coast groundfish trawl survey.................................................................................................................................................60 Figure 10. Canary rockfish distribution and relative abundance from the 2005 West Coast groundfish trawl survey.................................................................................................................................................61 Figure 11. Chilipepper rockfish distribution and relative abundance from the 2005 West Coast groundfish trawl survey. .............................................................................................................................62 Figure 12. Darkblotched rockfish distribution and relative abundance from the 2005 West Coast groundfish trawl survey. .............................................................................................................................63