In the first half of the 19th century there were three important whaling grounds adjacent to Papua New Guinea (PNG). The most extensive was on the northern coast of the main island on either side of the 140 degree east longitude where killings were made in October and November. Other important grounds stretched from the northern tip of New Ireland to Bougainville (fished in February and March), and off the northeast coast of the main island (fished from October to January). There is evidence of intermittent contact between whaling ships’ crews (from the United States, Britain and Australia) and the coastal people of the islands, particularly New Ireland, the Duke of Yorks group, Buka and Bougainville, where ships stopped for food and water. Occasionally PNGans were taken on as crew. These contacts, and the contacts with traders, are thought to have been important for the development of Tok Pisin.