The data set is composed of raw files recorded with the Kongsberg Maritime SX90 long-range, low frequency (20-30 kHz) fisheries sonar during the CCGS Amundsen 2013 summer expedition in the Eastern Canadian Arctic. The sonar transducer is lowered 2.5 feet below the hull through a gate-valve. The cylindrical 256-elements transducer allows both a horizontal and a vertical sound transmission, and the omni-directional (horizontal) sonar beam can be tilted from +10 to -60 degrees to scan a large portion of the water column. The raw acoustic data were saved onto an external drive and print screens of interesting targets (fish schools) were recorded.

The data set is composed of raw files recorded with a SIMRAD EK60 three-frequency (38, 120, 200 kHz) split-beam echosounder that was operated continuously during the 2012, 2013, and 2014 BREA cruise aboard the F/V Frosti. This entry also includes EK60 data collected during the ArcticNet cruise aboard the CCGS Amundsen in 2014. All three 7° transducers were hull-mounted and calibrated prior to departure. The acoustic signal was recorded continuously on a PC using ER60 software version 2.0.0. Ping interval was set around 1 s and the pulse length was set at 1.024 ms.

The data set is composed of raw files recorded with a SIMRAD EK60 three-frequency split-beam echosounder that was operated continuously during the annual ArcticNet (2005-2010) and the 15 months IPY-CFL (2007-2008) sampling expeditions aboard the CCGS Amundsen. Three 7° transducers were hull-mounted, two in oil-filled arctic wells protected by a 2.5 cm thick acoustically transparent polycarbonate plate (38 and 120 kHz) and one in a Traveocean piston well in direct contact with water (200 kHz). The acoustic signal was recorded continuously on a PC using ER60 software version 2.0.0. Ping interval was set at 2 or 3 s and the pulse length was set at 1.024 ms.

The dataset is composed of raw files (.raw) recorded with a SIMRAD EK60 three-frequency (38, 120, 200 kHz) split-beam echosounder that was operated continuously during the ArcticNet cruise aboard the CCGS Amundsen from 2006 to 2016 (no data were collected in 2012 due to the CCGS Amundsen being in dry dock). All three 7° transducers were hull-mounted and calibrated prior to departure. The acoustic signal was recorded continuously on a PC using ER60 software version 2.0.0. Ping rate varied from 1 to 2 seconds depending on maximum depth, and the pulse length was set at 1.024 milliseconds. The files can be read with the open source programming software R, other proprietary programming software like MATLAB or with specific proprietary software for hydro-acoustic analysis such as Echoview (https://www.echoview.com/​).

The dataset is composed of raw files (.raw) recorded with a SIMRAD EK60 three-frequency (38, 120, 200 kHz) split-beam echosounder that was operated continuously during the ArcticNet cruise aboard the CCGS Amundsen from 2017 to 2019. To ground-truth the hydroacoustic signal, various sampling techniques were applied throughout the cruise track such as midwater and bottom trawling as well as plankton net deployments.

The dataset is composed of raw files recorded with a SIMRAD EK60 three-frequency split-beam echosounder that was operated continuously during the annual ArcticNet (2005-2014) sampling expeditions in the Canadian Arctic aboard the CCGS Amundsen. Three 7° transducers were hull-mounted, two in oil-filled arctic wells protected by a 2.5 cm thick acoustically transparent polycarbonate plate (38 and 120 kHz) and one in a Traveocean piston well in direct contact with water (200 kHz). The acoustic signal was recorded continuously on a PC using ER60 software version 2.0.0. Ping interval was set at 2 or 3 s and the pulse length was set at 1.024 ms.

The data set is composed of raw files recorded with a SIMRAD EK60 three-frequency split-beam echosounder that was operated continuously during the annual ArcticNet (2005-2013) sampling expeditions in the Canadian Arctic and Subarctic aboard the CCGS Amundsen. Three 7° transducers were hull-mounted, two in oil-filled arctic wells protected by a 2.5 cm thick acoustically transparent polycarbonate plate (38 and 120 kHz) and one in a Traveocean piston well in direct contact with water (200 kHz). The acoustic signal was recorded continuously on a PC using ER60 software version 2.0.0. Ping interval was set at 2 or 3 s and the pulse length was set at 1.024 ms.

Video surveys were conducted in July 2016 aboard CCGS Amundsen, using a Super Mohawk remotely operated vehicle (ROV) at Hatton Basin, Labrador (Canada). ROV dives occurred at two nearby sites (~28 km apart) in the Hatton Basin area (Dives 50 and 51). The benthic environment was video-recorded and photographed using a high-definition camera (1Cam Alpha, Sub C Imaging, 24.1 megapixels) mounted on the ROV, at depths ranging between 556-633 m. ROV transects were conducted to collect video data, and samples of corals and sponges were also collected during dive 51. Box-cores were deployed at the two sites. Sea water was collected at several depth intervals from surface to near-bottom to characterize particulate organic matter and to determine calcium carbonate saturation.

The dataset is composed of adult fish species captured during the ArcticNet cruise aboard the CCGS Amundsen from 2017 to 2019. Pelagic fish were caught with an Isaacs-Kidd Midwater Trawl (IKMT, 9-m2 rectangular mouth aperture with mesh sizes of 11 mm in the first section and 5 mm in the last section). It was deployed from the surface to depths targeting possible aggregation of fish as recorded by the acoustic echosounder from the ship. Demersal and benthic fish were sampled with a bottom beam trawl (3-m2 rectangular aperture with a headline and a footrope of 4.27 m and a cod-end mesh of 9.5 mm) deployed on the seafloor. The pelagic and bottom trawls were towed at ~3 knots for 10 to 20 min. All fish collected by the trawls were measured and identified at least to the family level before freezing at -20°C.

A video-survey (Dive 52) using a Super Mohawk remotely operated vehicle (ROV) was conducted in July 2016 at Saglek Bank (Labrador, Canada). The benthic environment was video-recorded and photographed using a high-definition camera (1Cam Alpha, Sub C Imaging, 24.1 megapixels) mounted on the ROV, surveying depths ranging between 363-473 m. At this site, a video transect was prioritized over sampling, but 1 coral sample and 2 sponges were collected. At this location, three box-cores were deployed at two nearby sites, from which only a small sample was retained. Sea water was collected at several depth intervals from surface to near-bottom to determine calcium carbonate saturation.