The RAN's patrol boats' primary task across northern Australia is to protect the nation's fish stocks and intercept vessels bringing illegal immigrants to our shores.

Presently there are six patrol boats home ported in Darwin.

Four more will be moved from Sydney and Perth to DNB next year.

The majority of craft stopped by the 250 tonne high-speed patrol boats are from Indonesia.

Sometimes their cargoes as human, often shark fins, trochus or whole fish taken by the long line method of fishing.

Our two pictures taken by Darwin-based Defence photographers show a sailor holding just some of the long-line hooks used by poachers.

The second picture shows RAN sailors aboard a fishing craft.