Veteran lock Kristian Ormsby ensured the Steelers entered the interval at Eden Park on level terms after Howlett's opening try.
However, a second-half blitz of five tries, including two for Blues flanker Onosai Tololima Auva'a, ensured a winning start by the home team.
Canterbury, the 2004 title winners, also produced a late burst to complete a 34-3 win over Bay of Plenty at Jade Stadium.
Young winger Sean Maitland crossed the line three minutes from time to seal a bonus point.
At Whangarei, Harbour were held 27-27 by derby rivals Northland.
Veteran fly-half David Holwell scored 17 points to put the Taniwhas in sight of a rare victory, but prop James Afoa's late try salvaged a share of the spoils for Harbour.