Dolphin harassment, rubbish ditched in the sea, boats speeding past swimmers - those are just a few of the issues police say they've encountered on patrol in the Bay of Islands.

Far North police have borrowed a 12m rigid inflatable boat from the maritime police unit in Auckland from December 29 until Waitangi weekend.

Together with staff from the emergency services, the Department of Conservation (DoC), Northern Regional Council (NRC) and the Ministry of Primary Industries (MPI), they've been on the water daily. The behaviour of some boaties has been alarming, Constable Marco van den Broek said.

"We've been tripping over trouble. People simply don't know the basics - whether it be maritime rules, conservation requirements or fisheries limits. It has been visitors from out of town, mainly Auckland, that have been the most problematic," he said.


In particular the crew constantly had to school skippers on the speed limits, which are 5 knots (about 9km/h) within 200m of shore or any boat with a dive flag, and within 50m of any other boat or swimmer. Rubbish and dogs on beaches were other common issues, DoC ranger Adrian Walker said.

"We've fished bags of rubbish out of the water and cleared away piles of beer bottles. DoC works with Guardians of the Bay and local Rawhiti hapu to maintain the Bay's pest-free islands. They are sanctuaries, there for the conservation of our taonga and for everyone to enjoy. They're not rubbish dumps or dog toilets."

The NRC, DoC and the Far North District Council operated a rubbish barge, moored off the southeastern end of Moturua Island, to take boaties' rubbish every few days during summer.

Another issue was harassment of the Bay's declining bottlenose dolphin population. With rangers out on the police boat, DoC was able to respond quickly to calls on 0800 DOC HOT reporting mistreatment of marine mammals. The regulations prohibited boaties from driving through groups of dolphins and limited the number of vessels viewing a pod to three at any one time. Dolphins should be approached from behind and to the side, at no-wake speed within 300m. Local guidelines also required boats to give dolphins a 11.30am-1pm "lunch break" and stay 100m from mothers and calves.