Protecting our Beaches in New Zealand

Unbelievable Pollution at Muriwai Beach on the West Coast of New Zealand.
I’m away in the U.K. for 14 months and come home to find my Favourite Beach Polluted with small Fish belly up and Starfish dead yet I saw and Asian Family collecting Oysters and Mussels off of the Rocks which is Illegal.
The Man had a Fishing knife strapped to his leg and when they saw me watching they grabbed their bucket and made a hasty get away.
The Ranger was no where in sight and I can only Imagine that the Family got Seafood Poisoning.
What happened to Muriwai?
I went to Piha Beach and it was a beautiful and clean as ever.
Who looks after Our Beaches?
I would certainly like to know.
Clean Green New Zealand is not up to par with the West Coast Beaches.
Who do I contact to sort this out?
Someone is responsible!
Molly.