2015 Pollock Acoustic/Trawl Survey Gulf of Alaska EK60 Raw Data

Scientists from the Midwater Assessment and Conservation Engineering (MACE) Program of the Alaska Fisheries Science Center's (AFSC) Resource Assessment and Conservation Engineering (RACE) Division conducted an acoustic-trawl (AT) stock assessment survey of the western Gulf of Alaska (GOA) shelf to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus) in summer 2015. Previous surveys of the GOA were also conducted during the summers of 2003, 2005, 2011, and 2013 by MACE. The 2015 survey covered the shelf from the Islands of Four Mountains to Yakutat Trough including many associated bays and troughs. The biomass estimate for the entire survey area was 1,482,668 t. The majority of the pollock observed were located on the continental shelf (64%), Shelikof Strait (19%), east of Kodiak Island in Chiniak (2%) and Barnabas Troughs (6%), and in Marmot Bay (3%). The vast majority (91%) of the biomass for the entire survey was from fish 30-50 cm in length (likely mostly age-3 fish), Fish weight at length was slightly lower in fish greater than 40 cm FL compared to surveys conducted in the summer GOA in previous years. Backscatter was attributed to other species where possible. A biomass estimate was also calculated for Pacific ocean perch (Sebastes alutus, 407,988 t) and the relative abundance and distribution for euphausiids (primarily consisting of Thysanoessa inermis, but also including T. spinifera, T. raschii, and Euphausia pacifica) was estimated.

Go to https://www.ngdc.noaa.gov/mgg/wcd/ or email Anderson, Charles (charles.anderson@noaa.gov)

The data set is still being analyzed and will not be available for distribution until it has been finalized and all QA/QC practices have been performed. Contact the Data Point Of Contact for estimated time of release.

User must read and fully comprehend the metadata prior to use. User must acknowledge the Originator when using the data set as a source. User must share data products developed using the source data set with the Originator. Data should not be used beyond the limits of the source scale.

These data were collected in accordance NOAA protocols for fisheries acoustics surveys and related sampling (Alaska Fisheries Science Center), 23 p. Prepared by Midwater Assessment and Conservation Engineering Program, Alaska Fish. Sci. Center, Natl. Mar. Fish. Serv., NOAA. Available online: http://www.afsc.noaa.gov/RACE/midwater/AFSC%20AT%20Survey%20Protocols_Feb%202013.pdf

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Acoustic data were recorded at the five split-beam frequencies using ER60 software and, as a backup, acoustic telegram data were logged with Myriax EchoLog 500 software. Acoustic measurements were collected from 16 m below the sea surface to within 0.5 m of the sounder-detected bottom or a maximum of 1,000 m in deep water. Data were analyzed using Myriax Echoview post-processing software. See National Marine Fisheries Service (NMFS) 2013. NOAA protocols for fisheries acoustics surveys and related sampling (Alaska Fisheries Science Center), 23 p. Prepared by Midwater Assessment and Conservation Engineering Program, Alaska Fish. Sci. Center, Natl. Mar. Fish. Serv., NOAA. Available online: http://www.afsc.noaa.gov/RACE/midwater/AFSC%20AT%20Survey%20Protocols_Feb%202013.pdf