We already have the data from the latest ICES First Interim Report of the Working Group on the Effects of Extraction of Marine Sediments on the Marine Ecosystem (WGEXT).
I can send you Coop Res Reports, but I am not sure you'll get more information than in the last one which was achieved during the last meeting in Iceland.
Did you check the EMODnet portal already? http://www.emodnet.eu/human-activities, maybe there you can find some data. However, it is restricted to European waters, so definitely no global data.