They did manage to close to within a couple of metres of the Canterbury line as the half-hour mark neared, grinding away with a series of charges one-off the ruck.
But centre Tim Bateman stripped the ball in the tackle and hared 80m downfield to reset the Canterbury attack.
Five minutes later, lock Dominic Bird barged over from a typically efficient Canterbury lineout drive, Richie Mo'unga's conversion giving the defending champions a 20-0 lead at halftime.
Tasman tackled the second half with more conviction, but although their defence was superb, they were let down by handling errors and turnovers at crucial times on attack.
Canterbury finished strongly, tries to skipper Luke Whitelock, second five- eighth Rob Thompson and lock Mitchell Dunshea to completing a dominant performance.
- NZN