NOAA Technical Memorandum NMFS-AFSC-374 doi:10.7289/V5/TM-AFSC-374 Data Report: 2017 Gulf of Alaska Bottom Trawl Survey P. G. von Szalay and N. W. Raring U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Alaska Fisheries Science Center March 2018 NOAA Technical Memorandum NMFS The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical Memorandum series to issue informal scientific and technical publications when complete formal review and editorial processing are not appropriate or feasible. Documents within this series reflect sound professional work and may be referenced in the formal scientific and technical literature. The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries Science Center continues the NMFS-F/NWC series established in 1970 by the Northwest Fisheries Center. The NMFS-NWFSC series is currently used by the Northwest Fisheries Science Center. This document should be cited as follows: von Szalay, P. G., and N. W. Raring. 2018. Data Report: 2017 Gulf of Alaska bottom trawl survey. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-374, 260 p. Document available: http://www.afsc.noaa.gov/Publications/AFSC-TM/NOAA-TM-AFSC-374.pdf Reference in this document to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. NOAA Technical Memorandum NMFS-AFSC-374 doi:10.7289/V5/TM-AFSC-374 Data Report: 2017 Gulf of Alaska Bottom Trawl Survey P. G. von Szalay and N. W. Raring Resource Assessment and Conservation Engineering Division Alaska Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration 7600 Sand Point Way N.E. Seattle, WA 98115 www.afsc.noaa.gov U.S. DEPARTMENT OF COMMERCE Wilbur L. Ross Jr., Secretary National Oceanic and Atmospheric Administration RDML Timothy Gallaudet (ret.), Acting Under Secretary and Administrator National Marine Fisheries Service Chris Oliver, Assistant Administrator for Fisheries March 2018 This document is available to the public through: National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 www.ntis.gov PREFACE This report presents data from the 2017 Gulf of Alaska groundfish survey conducted by the Alaska Fisheries Science Center of the National Marine Fisheries Service. It contains detailed descriptions of the survey planning and operations, species distribution and abundance charts, length frequency plots, tables of estimated biomass, catch per unit effort, average weight and length estimates, length-weight regression parameters, lists of identified species, survey strata specifications and charts, and trawl descriptions and diagrams. iii ABSTRACT Scientists of the Groundfish Assessment Program of Alaska Fisheries Science Center's Resource Assessment and Conservation Engineering (RACE) Division conducted the tenth Gulf of Alaska Biennial Bottom Trawl Survey during the summer of 2017. This survey extends to 15 the series of surveys, previously conducted every 3 years between 1984 and 1999, which constitute the time series used in stock assessments of Gulf of Alaska groundfish resources. The survey area covered the continental shelf and upper continental slope to 700 m in the Gulf of Alaska from Islands of Four Mountains (170°W long.) and approximately 2,800 km across the Gulf of Alaska to Dixon Entrance (133°25'W long.). The survey was conducted aboard two chartered commercial trawlers, the FV Ocean Explorer and FV Sea Storm. Trawl haul samples were successfully collected at 536 survey stations using standard RACE Division Poly Nor'Eastern high-opening bottom trawl nets with rubber bobbin roller gear. The primary survey objectives were to define the distribution and estimate the relative abundance of the principal groundfish species within the survey area, and to collect data to estimate biological parameters useful to groundfish researchers and managers including growth, length-weight relationships, feeding habits, and size, sex, and age composition. The survey also collected ancillary data requested by other research groups. A total of 161 fish and 364 invertebrate species were captured in the survey. Species with the highest total catch abundance (by weight) over the entire survey area were Pacific ocean perch (Sebastes alutus), arrowtooth flounder (Atheresthes stomias), walleye pollock (Gadus v chalcogrammus), Pacific halibut (Hippoglossus stenolepis), flathead sole (Hippoglossoides elassodon), giant grenadier (Coryphaenoides pectoralis), northern rockfish (Sebastes polyspinis), and sablefish (Anoplopoma fimbria). Survey results presented here include estimates of catch per unit of effort, biomass, population size composition, and length-weight relationships, as well as charts depicting the distribution of catch for commercially important species encountered during the survey. vi CONTENTS PREFACE ...................................................................................................................................... iii ABSTRACT .....................................................................................................................................v INTRODUCTION ...........................................................................................................................1 METHODS ......................................................................................................................................4 Survey Area .........................................................................................................................4 Vessels .................................................................................................................................7 Fishing Gear .........................................................................................................................8 Survey Design ......................................................................................................................9 Data Collection Techniques ...............................................................................................11 Collection and Processing of Samples ...............................................................................12 Abundance, Size Composition, and Length-Weight Relations .........................................16 Survey Limitations .............................................................................................................18 RESULTS ......................................................................................................................................19 Catch Results by Area ........................................................................................................21 Catch Results by Species ...................................................................................................23 FLATFISHES ................................................................................................................................24 Arrowtooth Flounder .........................................................................................................24 Pacific Halibut ...................................................................................................................31 Flathead Sole ......................................................................................................................38 Southern Rock Sole............................................................................................................45 Northern Rock Sole............................................................................................................52 Rex Sole .............................................................................................................................59 Dover Sole .........................................................................................................................66 Yellowfin Sole ...................................................................................................................73 Other Flatfishes ..................................................................................................................80 Alaska Plaice ..........................................................................................................80 Starry Flounder ......................................................................................................80 English Sole ...........................................................................................................80 Butter Sole .............................................................................................................81 ROUNDFISHES ............................................................................................................................90 Walleye Pollock .................................................................................................................90 Pacific Cod .........................................................................................................................97 Atka Mackerel ..................................................................................................................104 Sablefish ...........................................................................................................................111 Giant Grenadier ................................................................................................................118 ROCKFISHES .............................................................................................................................125