AFSC/RACE/MACE: Results of 2013 Pollock Acoustic/Trawl Survey Shelikof 201303

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 routinely conduct acoustic-trawl (AT) stock assessment surveys in the Gulf of Alaska (GOA) during late winter and early spring to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). Historically, most of these efforts have been focused on the Shelikof Strait area, which has been surveyed annually since 1981, except in 1982, when no survey was scheduled, and in 1999 and 2011, when all winter GOA surveys were cancelled (because of vessel delays). The Shumagin Islands area has been surveyed annually since 2001 (except in 2004 and 2011) with prior surveys in 1994-1996. Sanak Trough has been surveyed annually since 2002 (except in 2004 and 2011), and the GOA continental shelf break east of Chirikof Island to Barnabas Trough has been surveyed annually since 2002 with the exception of 2011. Marmot Bay has been surveyed in the winter a total of six times (1989, 1990, 1992, 2007, 2009, and 2010) and Morzhovoi Bay has been surveyed a total of three times (2006, 2007, and 2010). This report presents the results from AT surveys conducted in the aforementioned areas of the GOA during February and March 2013.

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

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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