The young start communicating with each other while still in the egg; this may help synchronise hatching. Newly hatched juveniles use various yelps and grunts. When startled, a warning sound emitted by one will send all the juveniles diving to the bottom of the water. Adults in the vicinity respond with growls, threats, and attacks. The distress noises of a youngster when handled at a ranching facility was observed to cause all the larger animals to become involved in frenzied activity, with some rushing towards the juvenile and others thrashing about in the water and slapping their heads down on the surface. The IUCN listed this crocodile as being "Vulnerable" in its Red List of Threatened Species in 1986 and 1988, but changed the assessment to "Least Concern" in 1996. At the time it was stated that the animal has a large area of suitable habitat and seemed to be plentiful. Its status has not been reassessed since then. It is included in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The skin of the New Guinea crocodile is valuable and in the 1950s and 1960s the animals in the northern population were heavily hunted to a point where they might have become extinct. Around 1970, legislation was put in place and they received some protection. In the period 1977 to 1980, the harvest of wild skins was over 20,000 per year but in the 1980s this declined to 12,000 to 20,000. As well as this, some 2,500 to 10,000 eggs and hatchlings were collected annually to raise on ranches. However, in 1995, the largest ranch on the island initiated a change of strategy to concentrate on raising the saltwater crocodile, and demand for the eggs and juveniles of the New Guinea crocodile dried up. Since then, cropping of wild animals has been controlled in both Indonesia and Papua New Guinea. In the former it is limited to a belly width of for wet skins and in the latter to salted skins with a belly width of . Some eggs and hatchlings are still removed from the nest and raised in enclosures and a similar programme has more recently been initiated for southern populations. In July 2018, a man was reportedly killed by a saltwater crocodile in a breeding farm in West Papua, Indonesia. Locals then killed 292 saltwater and New Guinea crocodiles at the farm in revenge.