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 2011 summer expedition in the Eastern Canadian Arctic. The sonar was operated during a 3 hours opportunistic survey offshore the Labrador coast on July 22nd and during a 18.75 hours opportunistic survey on July 30th. 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 and/or marine mammals) were recorded.

Ringed seals have been reported to enter and use extensively the moon pool on multiple occasions during the CASES project. A net was designed to attempt to capture ringed seals from the moon pool onboard the CCGS Amundsen during a three week period of leg 6a. Captured seals were to be restrained, measured and a satellite transmitter (SPLASH PTT/TDR - Wildlife Computer) attached on their back before release. While one ringed seal did use the moon pool to rest during the three week period, we were not able to physically capture and tag any seals during the trip. We ruled out the net as designed in the first place as a good seal catching device in the moon pool, and created a new design that should be more functional. Considering seals' behaviour (once seals have found the moon pool, they keep using it) and how the moon pool is used onboard the ship, we discovered it was not necessary to deploy the net overnight if no seals have been spotted in the moon pool the day before. We are confident though that a future attempt to catch seals onboard the CCGS Amundsen will have more chances to be successful.