Blue maomao throng in the half-light, along with demoiselles, rays, trevally and other schooling fish. It’s an object lesson in why marine reserves matter.

Smaller marines reserves protect resident species but offer little protection for fish that move outside its borders. Only very large marine reserves will protect large or migratory species such as kingfish, kahawai, sharks, tuna, whales, dolphins and billfish, such as marlin. At present, none of New Zealand’s largest marine reserves are near the mainland.