Tasman Bay and Sounds snapper do grow faster then their north island counterparts. They can reach sexual maturity in 2 years in Tasman Bay compared with 5 for the Hauraki gulf.
Snapper sizing can be difficult, because same grow faster then others, while same very old snapper but be relatively small fish. Same 70cm have been aged as young as 18 years. While the oldest Snapper ever recorded was 65 but only had a length of 67cm. This might be because the stock is so depleted nowadays that their is less competition for food allowing them to grow faster and larger.