Yep definitely a dredge,
http://home.planet.nl/~putcor/voacz.html good part about it tho is there will be deeper waters and newly released nutrients available to sealife soon after dredging.
I know it sounds odd but in the Pine River when they had dredging going on areas up to about 200m away that were not dredged yet were typically poor fishing areas. Yet fishing where the dredge had been in the past week or so was the place to fish. I scored several good sized jew and heaps of bream and flathead from these well and truely disturbed waters. This was a pattern that remained until dredging was halted there.
I would be heading out there soon and seeing what the area will fish like with the new seafloor.
Jack.