Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska (OD0501, EK60). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl (AT) stock assessment survey of walleye pollock (Theraga Chalcogramma) along sections of the Gulf of Alaska shelf and shelfbreak from the Islands of Four Mountains to south of Prince William Sound, 30 June to 30 July 2005. The survey was conducted aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation, utilizing a Simrad EK60 split-beam echosounder system. The vessel departed Kodiak, Alaska on 2 July and arrived in Kodiak on 29 July. The cruise was completed in two legs with a port call in Dutch Harbor, Alaska 12-13 July. The EK60 echosounder system was calibrated at the start of the cruise in Three Saints Bay, Kodiak Island, Alaska on 2 June, and at the end of the cruise in Three Saints Bay on 28 July 2005.

Echo Integration-Trawl Surveys of Walleye Pollock in Shelikof Strait and Along the Gulf of Alaska Shelf Break Between Chirikof and Middleton Islands 13-31 March, 2008 (OD2008-03). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl (AT) stock assessment survey in the Shelikof Strait area of the Gulf of Alaska (GOA) and along the GOA shelf break between Chirikof and Middleton Islands in the late winter/early spring of 2008 to estimate the distribution and abundance of walleye pollock (Theragra chalcogramma). The survey was conducted 13-31 March, departing from Kodiak, Alaska on 13 March and arriving in Kodiak, Alaska 31 March. The Shelikof Strait, Chirikof shelf break and part of the Gulf of Alaska shelf break surveys were conducted 13-21 March, followed by an acoustic system calibration and weather delay 22-23 March. Gear selectivity and trawl net codend comparison experimental gear trials were conducted 24-26 March. The vessel transited to the Gulf of Alaska at Middleton Island on 27 March, and the survey of the Gulf of Alaska shelf break area was conducted 28-31 March. The vessel arrived in Kodiak, Alaska on 31 March. A calibration of the Simrad EK60 echosounder system (the primary survey instrument) was conducted in Captains Bay, Unalaska Island, Alaska on 15 March. A second calibration was conducted on 22 March in Kizhuyak Bay, Kodiak Island Alaska on 22 March. The survey was conducted aboard NOAA Ship Oscar Dyson, a 64 meter fisheries research stern trawler equipped with acoustic and oceanographic instrumentation.

Acoustic-Trawl Surveys of Walleye Pollock (Gadus chalcogrammus) in the Gulf of Alaska (SH2019-04). 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 Shelikof Strait, Chirikof shelf break,and Marmot Bay areas of the Gulf of Alaska (GOA) in the late winter/early spring of 2019 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). This survey was conducted aboard NOAA Ship Bell M. Shimada, 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 6 March and conducted an acoustic system calibration in Kalsin Bay, Kodiak Island 7 March. The Shelikof Strait was conducted 7-16 March, the Chirikof shelf break sure was conducted 16-18 March, and the Marmot Bay survey was conducted 19-20 March. A post-cruise acoustic system calibration was conducted 20-21 March in Kalsin Bay and the vessel arrived in Kodiak, Alaska on 21 March.

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).

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 in the Shelikof Strait area of the Gulf of Alaska (GOA) in the late winter of 2021 to estimate distribution and abundance of walleye pollock (Gadus chalcogrammus). These 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 the survey was a Simrad EK80 split-beam scientific echosounder system utilizing five frequencies (18, 38, 70, 120, and 200 kHz). The vessel departed Kodiak, Alaska on 2 March and conducted the Shelikof Strait survey 3-10 March, and the Marmot Bay survey 13-15 March. A calibration of the EK80 echosounder was conducted prior to starting the surveys on 2 March in Kalsin Bay, Kodiak Island, Alaska and a follow-up post-cruise calibration was conducted in Kalsin Bay, Kodiak Island, Alaska on 15 March. Trawl operations were conducted using an LFS1421 mid-water trawl net.

Acoustic-Trawl Surveys of Walleye Pollock (Gadus chalcogrammus) in the Gulf of Alaska (SH2019-04). 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 Shelikof Strait, Chirikof shelf break,and Marmot Bay areas of the Gulf of Alaska (GOA) in the late winter/early spring of 2019 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). This survey was conducted aboard NOAA Ship Bell M. Shimada, 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 6 March and conducted an acoustic system calibration in Kalsin Bay, Kodiak Island 7 March. The Shelikof Strait was conducted 7-16 March, the Chirikof shelf break sure was conducted 16-18 March, and the Marmot Bay survey was conducted 19-20 March. A post-cruise acoustic system calibration was conducted 20-21 March in Kalsin Bay and the vessel arrived in Kodiak, Alaska on 21 March.

Acoustic-Trawl Surveys of Walleye Pollock in the Gulf of Alaska (DY2017-03). 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). The surveys were conducted aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation. The primary 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 14 March and surveyed Spruce Gully and inner Marmot Bay 14-15 March. The vessel returned to Kodiak for an unscheduled port call 15-17 March and departed Kodiak on 18 March. The Shelikof Strait survey was conducted 18-24 March followed by the Chirikof Shelfbreak survey 24-25 March. The outer Marmot Bay survey was conducted on 26 March. A sphere calibration of the echosounder system was conducted in Volcano Bay, Alaska on 14 February and at the end of the current cruise in Izhut Bay, Alaska on 27 March; no significant differences in gain parameters or transducer beam pattern characteristics were noted between the two calibrations. The vessel arrived at its homeport of Kodiak, Alaska on 27 March.

Acoustic-Trawl Surveys of Walleye Pollock (Gadus chalcogrammus) in the Gulf of Alaska (DY1803, 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 Shelikof Strait and Marmot Bay areas of the Gulf of Alaska (GOA) in the late winter/early spring of 2018 to estimate the distribution and abundance of walleye pollock (Gadus chalcogrammus). This survey was conducted 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 conducted an acoustic system calibration in Captains Bay, Dutch Harbor, Alaska on 12 March and departed Dutch Harbor on 13 March transiting toward Shelikof Strait. The Shelikof Strait survey was conducted 15-21 March followed by the Marmot Bay survey 21-22 March. A post-cruise calibration of the echosounder system was conducted at the end of the cruise on 23 March in Kalsin Bay, Kodiak Island, Alaska. The vessel returned to its homeport of Kodiak, Alaska on 23 March ending the cruise.

Oceanographic Survey of Cross Seamount and Control Sites (OES0703L1, EK60). The goals of the cruise were to collect acoustic backscatter and oceanographic data at Cross Seamount (18°43.285’ N, longitude 158° 15.710’ W), with an approximately 400 m deep plateau, and at control sites in the surrounding environment. Data collected consisted of CTD casts, trawl samples, and continuous monitoring of currents and biological acoustic backscatter. CTD cats were conducted at predetermined stations. CTDs were equipped with oxygen sensors and fluorometers, and water was sampled at discrete depths during each cast for chloropigment determinations. Trawl operations were conducted at predetermined stations using a Cobb trawl at depths of the shallow (nighttime) and deep (day and nighttime) sound scattering layers. Currents were continuously monitored using a RD Instruments Acoustic Doppler Current Profiler (ADCP) operating at 75 kHz frequency. Biological backscatter were recorded using the EK60 echosounder system (38, and 120 kHz) along predetermined transects.