The Snapper in the Kenepuru during winter was a fluke, sounds like they would chased out of the depths by dolphins. Even after the dolphins left the snapper stayed around in the shallows for days, they did not sound like happy fish.
Even up in Cloudy and Clifford bay snapper are a rare catch during the summer. So any Snapper done towards canterbury would be pure luck. Probably more likely then a Marlin in Tasman bay though.