This little landing craft is not a tug, but it does have an azimuthing stern drive- probably M&T Harbormater, but I could find no confirmation in my examination.
Although thought of as a recent innovaiton for tugs, steerable drives were developed during World War II for landing craft such as this, and are still in use. More sophisticated units have been used on tugs since the 1980s and have become known as Azimuthing Stern Drives.
This craft was built for the Canadian Coast Guard to assist with northern supply and aids to navigation, and was given the name GCU 407, by its builders E.S.M Québec Inc.
Just this year it has been refitted and re-registered as C211040QC, (a Canadian registration number, with the Quebec province locator). It is owned by Larinda Inc., a company associated with LeGrow's Marine in Dartmouth, operators of several small tugs and workboats in Halifax harbour.
This appears to be the same landing craft that had for years been parked in one of the sheds on pier 9. I think that it was owned by Beaver Marine (now part of MacNally Marine).