Northern Territory rangers have removed a large saltwater crocodile from a trap near Katherine.

The 3.9-metre croc was found at Donkey Camp on the Katherine River on Monday.

Earlier this year, a 4.6-metre saltie was caught in the same trap.

More than 180 crocodiles have been caught by rangers so far this year.

Parks and Wildlife Service senior ranger John Burke says the trap at Donkey Camp is located 15 kilometres upstream from the Katherine and 10 kilometres downstream from Nitmiluk National Park.

"We think this crocodile has been in the area for a while but has evaded our traps until now, as crocodiles are usually less active during the colder months," he said.

"As the weather heats up and temperatures rise, crocodiles become more active and more likely to move around looking for food.

"This is another reminder to people to be extremely cautious about any waterways in the Top End, because estuarine crocodiles can and do move around throughout the year."