The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries, Alaska Fisheries Science Center (AFSC), conducted an acoustic-trawl (AT) stock assessment survey in the Shelikof Strait area of the Gulf of Alaska (GOA) in the late winter of 2022 to estimate distribution and abundance of walleye pollock (Gadus chalcogrammus). This survey was conducted aboard NOAA Ship Oscar Dyson (built in 2003, 64 meters, 2500 tons, 3100 hp), a research stern trawler equipped with acoustic and oceanographic instrumentation. The primary water column acoustic instrument for the survey was a Kongsberg EK80 split-beam scientific echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz). The vessel departed Kodiak, Alaska on 8 March and conducted the Shelikof Strait survey 9-16 March. A calibration of the EK80 echosounder system was conducted prior to starting the survey on 8 March in Kalsin Bay, Kodiak Island, Alaska. Trawl operations were conducted using an LFS1421 mid-water trawl net.

Assessment of Rockfish Species in Untrawlable Habitat in the Gulf of Alaska (DY0912, EK60). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted an assessment of northern rockfish (Sebastes polyspinis) and dusky rockfish (Sebastes variabilis) in untrawlable habitat areas of the Gulf of Alaska using advanced acoustics, optical, and trawl technologies, 3-13 October 2009. The primary survey site was a shallow bank along the GOA shelf break known as Snakehead. The survey was conducted aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation. The primary acoustic instruments for this survey were the Simrad EK60 split beam echosounder and the Simrad ME70 multibeam echosounder. The vessel departed Dutch Harbor, Alaska on 3 October and ended the cruise on 13 October in Kodiak, Alaska. The survey was conducted 4-12 October with a weather delay on 10 October.

Acoustic-Trawl Surveys of Walleye Pollock in the Central Gulf of Alaska (DY0904, EK60). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted acoustic-trawl (AT) stock assessment surveys in the central Gulf of Alaska (GOA) during the late winter/early spring of 2009 to estimate the distribution and abundance of walleye pollock (Theragra chalcogramma). The vessel departed Kodiak, Alaska on 19 March and conducted a survey along the central Gulf of Alaska shelf east of Chirikof Island 20-22 March. The vessel then surveyed Shelikof Strait 23-28 March and performed an acoustic equipment calibration on 29 March. The Marmot Bay survey was conducted 29-30 March followed by fisheries research equipment testing on 31 March. The vessel ended the cruise in Kodiak, Alaska on 1 April. The survey was conducted aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation.

Gulf of Alaska Acoustic-Trawl Surveys of Walleye Pollock (DY0901, EK60). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted acoustic-trawl (AT) stock assessment surveys in the western Gulf of Alaska (GOA) during the winter of 2009 to estimate the distribution and abundance of walleye pollock (Theragra chalcogramma). The vessel departed Kodiak, Alaska on 12 February and conducted acoustic echosounder system calibrations in Three Saints Bay, Kodiak Island, Alaska on 12-13 February. The vessel conducted the Shumagin Islands survey (including Shumagin Trough, Stepovak Bay, Renshaw Point, Unga Strait, and West Nagai Strait) 15-18 February. The vessel then surveyed Sanak Trough on 18-19 February, followed by a survey of the continental shelf break from Sanak Island to Unalaska Island 19-20 February. The vessel conducted equipment research operations utilizing a lowered target strength transducer system 21-22 February and arrived in Dutch Harbor, Alaska on 22 February. The primary acoustic echosounder system for this survey was a Simrad EK60; a Simrad ME70 multibeam echosounder system was also operated for the duration of the cruise. The survey was conducted aboard NOAA Ship Oscar Dyson, a 64 meter fisheries research stern trawler equipped with acoustic and oceanographic instrumentation.

The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries, Alaska Fisheries Science Center (AFSC), conducted acoustic-trawl (AT) stock assessment surveys on the Gulf of Alaska (GOA) shelf and associated bays during the late spring and summer of 2019 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). The survey was conducted 30 May - 7 August aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation. The primary acoustic instrument for the survey was a Simrad EK60 split-beam echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz). The vessel departed Kodiak, Alaska on 30 May and conducted the survey in three legs with all port calls in Kodiak; the project was completed in Kodiak on August 7. Leg 1 of the project was conducted 30 May \u2013 20 June on the Gulf of Alaska (GOA) shelf from the Islands of Four Mountains to outer Shumagin Trough including Sanak Trough, Morzhovoi Bay, Shumagin Islands area, and Mitrofania area. The leg 2 surveys were conducted 25 June \u2013 16 July in Shelikof Strait, Alitak Bay, Barnabas Trough, Chiniak Trough, and on the Alaska shelf. The leg 3 surveys were conducted 19 July \u2013 7 August and included Marmot Bay, Resurrection Bay, Prince William Sound, and the Alaska shelf from Kodiak to Yakutat Bay. Calibrations of the echosounder system were conducted in Kalsin Bay, Kodiak Island, Alaska at the start and end of the cruise; no significant differences in gain parameters or transducer beam pattern characteristics were noted between the two calibrations.

The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries, Alaska Fisheries Science Center (AFSC) conducted acoustic-trawl (AT) stock assessment surveys in the Gulf of Alaska (GOA) 1 June to 10 July 2021 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). The survey was conducted along the Gulf of Alaska shelf from the Islands of Four Mountains to Yakutat Trough. Survey operations were conducted aboard NOAA Ship Oscar Dyson, a 64 meter fisheries research vessel built in 2003 and equipped for stern trawling and included capabilities to collect acoustic, oceanographic, and biological scientific data. Acoustic data was collected for the survey using a Kongsberg Simrad EK80 split-beam echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz). Mid-water trawls were conducted using an LFS 1421 mid-water trawl net equipped with a Kongsberg Simrad FS70 trawl sonar. The survey was divided into two segments with the first segment conducted from 1 June to 20 and the second segment conducted 24 June to 10 July with a mid-survey port call in Kodiak. The vessel departed Kodiak, Alaska on 1 June and conducted a calibration of the EK80 system prior to starting survey operations. The survey areas included the Gulf of Alaska shelf from the Islands of Four Mountains to southeast Kodiak Island, the Shumagin Islands, Barnabas Trough, Shelikof Strait, Chiniak Trough, and the Gulf of Alaska shelf from southeast Kodiak Island to Yakutat Trough. A post-survey calibration of the EK80 echosounder was completed prior to arrival in Kodiak, Alaska on July 10.

The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries (NMFS), Alaska Fisheries Science Center (AFSC), conducted acoustic-trawl (AT) stock assessment surveys in the Shumagin Islands and Pavlof Bay areas of the Gulf of Alaska (GOA) 4-12 February, 2024, to estimate distribution and abundance of walleye pollock (Gadus chalcogrammus). The survey was conducted aboard NOAA Ship Oscar Dyson (built in 2003, 64 meters, 2500 tons, 3100 hp), a research stern trawler equipped with acoustic and oceanographic instrumentation. The primary water column acoustic instrument for these surveys was a Kongsberg EK80 split-beam scientific echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz). The vessel departed Kodiak, Alaska on 4 February and conducted the Shumagin Islands survey 6-11 February, and the Pavlof Bay survey 9-10 February. A calibration of the EK80 echosounder system was conducted following vessel departure from Kodiak and prior to starting the survey on 4 February in Kalsin Bay, Kodiak Island, Alaska. Trawl operations were conducted using an LFS1421 mid-water trawl net equipped with a Kongsberg FS70 trawl sonar.

Echo Integration-Trawl Surveys of Walleye Pollock in the Shumagin Islands and Sanak Trough areas of the Gulf of Alaska, 6-15 February, 2008 (DY2008-01). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted acoustic-trawl (AT) stock assessment surveys in the Shumagin Islands and Sanak Trough areas of the Gulf of Alaska (GOA) during the winter of 2008 to estimate the distribution and abundance of walleye pollock (Theragra chalcogramma). This cruise was also used as an opportunity to compare results from acoustic-trawl surveys conducted simultaneously between NOAA Ships Oscar Dyson and Miller Freeman. This survey was conducted onboard NOAA Ship Oscar Dyson, departing from Kodiak, Alaska on 6 February and arriving in Dutch Harbor, Alaska on 15 February. A calibration of the echosounder system was conducted in Three Saints Bay, Kodiak Island, Alaska on 6 February. Both vessels (Freeman accompanying the Dyson) conducted the Shumagin Islands survey (including Shumagin Trough, Stepovak Bay, Renshaw Point, and Unga Strait) 7-12 February. The vessels conducted the survey of Sanak Trough 12-13 February. The experimental intervessel comparison work required that the vessels travel side-by-side along the survey transects at a separation distance of 0.5 nm, and at other times following each other at a distance of 1.0 nm along shorter transects. The intervessel comparison was designed to minimally impact efforts to complete the survey with the Miller Freeman as the primary survey vessel. A calibration of the Dyson echosounder system was conducted at the end of the survey in Captains Bay, Dutch Harbor, Alaska on 15 February. The Dyson arrived in Dutch Harbor, Alaska on 15 February, ending the cruise. The Dyson is a 64 meter fisheries research stern trawler equipped with acoustic and oceanographic instrumentation. The primary acoustic echosounder system installed on the Dyson is a Simrad EK60 scientific split beam echosounder utilizing five frequencies (18, 38, 70, 120, and 200 kHz).

Acoustic-Trawl Surveys of Walleye Pollock in the Gulf of Alaska (DY1702, EK60). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries, Alaska Fisheries Science Center (AFSC) conducted acoustic-trawl (AT) stock assessment surveys in the Gulf of Alaska (GOA) during the winter and early spring of 2017 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). These surveys were conducted aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation. The primary instrument for the surveys was a Simrad EK60 split-beam echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz). The vessel departed Kodiak, Alaska on 1 March and conducted the Kenai Bays survey (including Port Dick, Nuka Passage, Harris Bay, Aialik Bay, Resurrection Bay, Day Harbor, and Port Bainbridge) 2-5 March. The Prince William Sound, Hinchinbrook Trough and Middleton Island surveys were conducted 5-9 March. A calibration of the echosounder system was conducted during the previous cruise on 14 February in Volcano Bay, Alaska. The vessel arrived at its homeport of Kodiak, Alaska on 10 March, 2017.

The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries (NMFS), Alaska Fisheries Science Center (AFSC), conducted acoustic-trawl (AT) stock assessment surveys in the Shelikof Strait and Chirikof Shelf break areas of the Gulf of Alaska (GOA) 5-20 March, 2024, to estimate distribution and abundance of walleye pollock (Gadus chalcogrammus). The surveys were conducted aboard NOAA Ship Oscar Dyson (built in 2003, 64 meters, 2500 tons, 3100 hp), a research stern trawler equipped with acoustic and oceanographic instrumentation. The primary water column acoustic instrument for these surveys was a Kongsberg EK80 split-beam scientific echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz). The vessel departed Kodiak, Alaska on 5 March and conducted the Shelikof Strait survey 6-17 March, and the Chirikof Shelf break survey 17-19 March. A calibration of the EK80 echosounder system was conducted during a previous survey (DY2401) on 4 February in Kalsin Bay, Kodiak Island, Alaska, and a post-survey calibration was conducted in Uyak Bay, Kodiak Island, Alaska, on 9 March. Trawl operations were conducted using an LFS1421 mid-water trawl net equipped with a Kongsberg FS70 trawl sonar.