Upon arrival, the trawlers were put to use in both minesweeping and patrol roles. In April 1918, four of the trawlers were used for port defence of Halifax and others were used to escort slow convoys through Canadian waters. In order to fill the manpower need for the trawlers, ratings from the Newfoundland division of the Royal Navy Reserve were sent to Canada. By mid-summer 35 of the 36 trawlers were active with the last, "TR 20", awaiting her crew at Kingston, Ontario.