Following up, the CBC in St. John's Newfoundland has stated that they will be showing the sidescan images on their television program "Here and Now" this evening (6:00 PM local time / -3.5 hrs GMT): [www.cbc.ca]

I suspect that these might have been collected by the Geological Survey of Canada or Hydrographic services. I have contacts in both organizations and will see if more information is available.

Cheers,

David