Canada couldn't keep up their performance in the second stanza, as the gulf in class between the world number four Black Sticks and 19th-ranked Canadians shone through.
A Liz Thompson penalty and Kayla Whitelock strike sealed the contest, before Harrison and Merry claimed doubles to finish the rout.
Black Sticks captain Sam Charlton said her side will be looking to put in a more fluent first quarter in the second match of the series.
"Canada came out hard and were more intense, it took us a bit too long to adjust but once we got our structure going and the ball moving quicker it started to work for us.
"We need to start a lot better tomorrow and come out with some fire, make sure we make those simple traps and passes and as we saw today the opportunities will come," said Charlton.
The two sides face off again at 3.00pm tomorrow, before taking part in the eight-team Hawke's Bay Cup, a tournament featuring five of the world's top ten sides.