The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries, Alaska Fisheries Science Center (AFSC) conducted acoustic stock assessment surveys in the eastern Bering Sea (EBS) in summer of 2020 to estimate distribution and abundance of walleye pollock (Gadus chalcogrammus). This survey was initially intended as a ship-based survey, but this was cancelled due to the emerging COVID-19 pandemic. The survey was completed by three chartered 7 meter saildrone USVs. The primary water column acoustic instrument for the survey was a Simrad EK80 mini scientific echosounder system equipped with a dual frequency ES38-18/200-18CR transducer (38 kHz split-beam, 200 kHz single beam). The vessels departed Alameda, CA on 13-14 May, conducted an acoustic survey of the Bering Sea from 4-20 August, and returned to Alameda on 4 October. The echosounder system was calibrated via the standard sphere method before and after the cruise.

The Midwater Assessment and Conservation Engineering (MACE) program of NOAA Fisheries, Alaska Fisheries Science Center (AFSC) conducted acoustic stock assessment surveys in the eastern Bering Sea (EBS) in summer of 2020 to estimate distribution and abundance of walleye pollock (Gadus chalcogrammus). This survey was initially intended as a ship-based survey, but this was cancelled due to the emerging COVID-19 pandemic. The survey was completed by three chartered 7 meter saildrone USVs. The primary water column acoustic instrument for the survey was a Simrad EK80 mini scientific echosounder system equipped with a dual frequency ES38-18/200-18CR transducer (38 kHz split-beam, 200 kHz single beam). The vessels departed Alameda, CA on 13-14 May, conducted an acoustic survey of the Bering Sea from 4-20 August, and returned to Alameda on 4 October. The echosounder system was calibrated via the standard sphere method before and after the cruise.

AFSC Echo Integration-Trawl of Walleye Pollock (Theraga chalcogramma) on the U.S. and Russian Bering Sea Shelf in June and July 2007 (OD0707, 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 survey of abundance and distribution of walleye pollock (Theragra chalcogramma; Gadus chalcogramma) on the U.S eastern Bering Sea shelf and Russian Cape Navarin areas 2 June to 30 July 2007. 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 equipped with five frequencies (18, 38, 70, 120, and 200 kHz). The survey was conducted in three legs starting and ending in Dutch Harbor, Alaska with all port calls in Dutch Harbor. Leg 1 was conducted 2-20 June, leg 2 was conducted 21 June to 9 July, and leg 3 was conducted 11-30 July. Standard acoustic system sphere calibrations were conducted at the start of the cruise (2 June), at the start of leg 2 (21 June), at the end of leg 2 (8 July), and at the end of the cruise (29 July); all calibrations were accomplished in Captains Bay, Dutch Harbor.

Acoustic-Trawl Survey of Walleye Pollock on the U.S. and Russian Bering Sea Shelf (DY0909, 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 on the U.S. and Russian Bering Sea shelf during late spring/summer of 2009 to estimate the distribution and abundance of walleye pollock (Theragra chalcogramma). The survey was conducted from Bristol Bay, eastern Bering Sea in the U.S. to Cape Navarin, Russia, 9 June to 7 August aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation. The vessel departed Kodiak, Alaska on 5 June and arrived in Dutch Harbor on 7 August. The cruise was completed in three legs (leg 1, 9-28 June; leg 2, 1-18 July; leg 3, 21 July to 7 August), with port calls in Dutch Harbor, Alaska; a personnel exchange occurred in Dutch Harbor on 21 June. Fisheries gear research operations were conducted on 16 June and again 3-5 August. The EK60 echosounder system was calibrated at the start of the cruise in Three Saints Bay, Kodiak Island, Alaska 10-11 June, and at the end of the cruise in Anderson Bay, Unalaska Island, Alaska 6-7 August.

Echo Integration-Trawl Survey of Walleye Pollock (Theraga chalcogramma) on the U.S. and Russian Bering Sea Shelf (OD2008-09). 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 on the U.S. and Russian Bering Sea shelf during late spring/summer of 2008 to estimate the distribution and abundance of walleye pollock (Theragra chalcogramma). The survey was conducted from Bristol Bay, eastern Bering Sea in the U.S. to Cape Navarin, Russia, 2 June to 31 August aboard NOAA Ship Oscar Dyson, a 64 meter stern trawler equipped with acoustic and oceanographic instrumentation. The vessel departed Dutch Harbor, Alaska on 2 June and arrived in Dutch Harbor on 31 July. The cruise was completed in three legs (leg 1, 2-19 June; leg 2, 21 June to 10 July; leg 3, 11-31 July), with port calls in Dutch Harbor, Alaska. Experimental and research gear operations were conducted during non-daylight hours and paired trawl net codend comparison experiments and intervessel comparison studies were conducted with NOAA Ship Miller Freeman 20-28 July. The Simrad EK60 scientific echosounder system is the primary acoustic instrument installed on the Dyson and was calibrated at the start of the cruise in Captains Bay, Unalaska Island, Alaska on 2 June, mid-cruise in Captains Bay on 11 July, and at the end of the cruise in Nateekin Bay, Unalaska Island, Alaska on 31 July.

A bottom moored echosounder was deployed at 137.6 m depth in the NW Bering Sea (61.06918 N, 177.73993 W) from 26 July 2019 to 31 August 2020. The mooring was instrumented with a battery powered EK80 wideband autonomous transceiver (WBAT, Simrad AS). The echosounder operated an upwards facing depth-rated 70 kHz 18° split-beam transducer (ES70-18CD), positioned upward with a two-axis gimbal equipped with a 0.7 kg counterweight. During the deployment, the WBAT was programmed to transmit an ensemble of 320 narrowband and 35 wideband every two hours. Data were recorded to a range of 155 m. Calibrations had occured in Seattle, Washington either prior to deployment or after recovery using a 38.1-mm tungsten carbide sphere following the standard sphere method (Demer et al., 2015).

A bottom moored echosounder was deployed at 116.3 m depth in the NW Bering Sea (61.36881 N, 177.17 W) from 26 July 2019 to 31 August 2020. The mooring was instrumented with a battery powered EK80 wideband autonomous transceiver (WBAT, Simrad AS). The echosounder operated an upwards facing depth-rated 70 kHz 18° split-beam transducer (ES70-18CD), positioned upward with a two-axis gimbal equipped with a 0.7 kg counterweight. During the deployment, the WBAT was programmed to transmit an ensemble of 320 narrowband and 35 wideband every two hours. Data were recorded to a range of 155 m. Calibrations had occured in Seattle, Washington either prior to deployment or after recovery using a 38.1-mm tungsten carbide sphere following the standard sphere method (Demer et al., 2015).

AFSC Inter-Vessel Comparison of NOAA Ships Oscar Dyson and Miller Freeman in the Bogoslof Island Area (OD0703, EK60). The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted an inter-vessel comparison of NOAA Ships Oscar Dyson and Miller Freeman in the Bogoslof Island area of Alaska 1-10 March 2007. The inter-vessel comparison 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 equipped with five frequencies (18, 38, 70, 120, and 200 kHz). The vessel departed Dutch Harbor, Alaska on 1 March and arrived in Dutch Harbor on 10 March. The EK60 echosounder system was calibrated at the start of the cruise in Captains Bay, Dutch Harbor and again at the end of the cruise in Portage Bay (Makushin Bay), Unalaska Island, Alaska on 10 March.

A bottom moored echosounder was deployed at 77.35 m depth in the NW Bering Sea (62.2903 N, 175.3713 W) from 26 July 2019 to 31 August 2020. The mooring was instrumented with a battery powered EK80 wideband autonomous transceiver (WBAT, Simrad AS). The echosounder operated an upwards facing depth-rated 70 kHz 18° split-beam transducer (ES70-18CD), positioned upward with a two-axis gimbal equipped with a 0.7 kg counterweight. During the deployment, the WBAT was programmed to transmit an ensemble of 320 narrowband and 35 wideband every two hours. Data were recorded to a range of 155 m. Calibrations had occured in Seattle, Washington either prior to deployment or after recovery using a 38.1-mm tungsten carbide sphere following the standard sphere method (Demer et al., 2015).

A bottom moored echosounder was deployed at 95.6 m depth in the NW Bering Sea (61.85022 N, 176.25066 W) from 26 July 2019 to 31 August 2020. The mooring was instrumented with a battery powered EK80 wideband autonomous transceiver (WBAT, Simrad AS). The echosounder operated an upwards facing depth-rated 70 kHz 18° split-beam transducer (ES70-18CD), positioned upward with a two-axis gimbal equipped with a 0.7 kg counterweight. During the deployment, the WBAT was programmed to transmit an ensemble of 320 narrowband and 35 wideband every two hours. Data were recorded to a range of 155 m. Calibrations had occured in Seattle, Washington either prior to deployment or after recovery using a 38.1-mm tungsten carbide sphere following the standard sphere method (Demer et al., 2015).