Crocodylus novaeguineae

Common names: New Guinea crocodile, Buaya air tawar, Pukpuk, Wahne huala Range: Indonesia (Irian Jaya only), Papua New Guinea Revised by Philip M. Hall

CITES: Appendix II
CSG Action Plan: Availability of Survey Data – Adequate
Need for Wild Population Recovery – Moderate
Potential for Sustainable Management – Highest
1996 IUCN Red List. Not Listed (LRlc. Lower Risk, least concern. The species appears to remain abundant in its extensive habitat.)
Principal threats: Illegal hunting, habitat disruption.

Ecology and natural history

The New Guinea crocodile is a medium-sized crocodile found only on the island of New Guinea. Maximum documented adult size is approximately 3m for females and 3.5m for males (Hall 1991b). Recent work (Hall 1989) describes morphological differences in cranial features and squamation between the southern (Papuan) population and northern populations and their putative similarities to the Philippine crocodile, Crocodylus mindorensis. This work suggests that the southern population of C. novaeguineae may be a distinct and as yet unnamed taxon. New Guinea crocodiles prefer freshwater habitats, and are found throughout most of New Guinea’s vast system of freshwater swamps and marshes.

Females become sexually mature at lengths from 1.6 to 2.0m, and lay eggs in mound nests. The northern population oviposits during the annual dry period, whereas the southern population nests during the wet season. Northern crocodiles also lay larger clutches of smaller eggs than do southern animals. Among northern animals, nests are usually found on floating mats of vegetation, frequently in densely overgrown channels and river tributaries (Cox 1985). Nests in the southern populations are more frequently located on land (Hall and Johnson 1987).

Populations of C. novaeguineae have benefited from the large amount of wetlands habitat and the low human population density on the island of New Guinea. Adequate survey data indicate the presence of good populations in both Irian Jaya (Indonesia) and Papua New Guinea. Commercial hunting of this species commenced following World War II and peaked in the 1960s. Management programs have been developed in both countries, and for practical reasons both C. porosus and C. novaeguineae are subject to the same regulations. The aim of the management programs in both countries is to regulate harvests of both wild skins and eggs or hatchlings for ranches at sustainable levels while providing equitable economic incentives to indigenous landowners for retention of the resource.

Conservation and status

In Papua New Guinea, the recognition of inefficient harvesting led to legislative controls in the late 1960s and the establishment of a regulated program in the 1970s based on cropping and ranching. Crocodiles are managed at sustainable levels for the benefit of traditional land owners who own most of the land in Papua New Guinea. Crocodiles can be legally harvested by land owners for personal use (food and ritual) but commercial sale and export of hides is restricted to the size range of 18–51cm belly width, which corresponds to approximately 0.9– 2.1m total length. Wild harvests have declined from in excess of 20,000/year (1977–1980) to 12,000–20,000/year (1981–1989) and are currently 3,000–5,000/ year (Anon 1994a, Solmu 1994). Over the same period, an increasing number of hatchlings and eggs have been collected and raised in centralized ranches, and harvests for this purpose have been in the range of 2,500–10,000 in recent years. Early attempts to establish village level ranches foundered due to technical limitations. Traditional owners now sell crocodile hatchlings and eggs to centralized raising facilities in exchange for cash and chicken eggs. Annual surveys of nests in a representative area of the Sepik river suggest the population has remained stable since 1981. A very extensive harvest data base exists on this species. Harvest data or skulls of harvested animals are extremely useful for monitoring populations especially in areas where spotlight or aerial surveys are logistically and economically impractical. For detailed analyses see Hall (1990a and b), Hall and Portier (1994) and Solmu (1994). Manolis (1995) recently reviewed the monitoring program in Papua New Guinea and found it basically sound. Recommendations were made to improve the standardization of data collection and the availability of trained personnel, to provide timely and pertinent analyses.

A similar management program is now under development in Irian Jaya, Indonesia. Basic surveys and development of egg and hatchling collection systems and ranches was undertaken during an extensive FAO funded project in 1986–1992 (Cox 1992). In the same period, extensive illegal hunting and smuggling of skins was addressed and aggressive enforcement of regulations initiated. At present, crocodile management in Indonesia is undergoing detailed redesign in response to concerns raised by the parties to CITES, CSG and other NGOs (Messel 1993, Thomsen 1993). With the assistance of expert consultancies (Webb and Jenkins 1991) and reviews by CSG teams (Messel, Jelden and Hemley 1992, Messel 1993), a coordinated management plan for both C. porosus and C. novaeguineae is being developed. Results to date include the formation of a Crocodile Management Task Force in the CITES Management Authority (PHPA), the adoption of enabling legislation for crocodile conservation regulations, the development of a tracking system for both ranched and wild hides, and the establishment of an interlocking system of licences and permits to regulate collection, movement, trade, ranching, processing and export of crocodilian products. In October 1994, Indonesia imposed a suspension of exports of all crocodile products (except personal effects) pending the completion and implementation of the new system.

In both Indonesia and Papua New Guinea, trade of wild skins is subject to an upper size limit, which aims to protect the proportion of the adult breeding population which exceed that size. In Papua New Guinea, trade occurs as salted skins between (18–51cm) belly widths. In Indonesia (Irian Jaya) crocodile trade is proposed in animals between (25–51cm) belly widths, but this applies to wet blue processed skins. Skins shrink during processing by an average of 10%. As a result the Indonesian size limits actually translate to around 28–56cm belly width of raw skins. The effect of this needs to be analysed. Differences in the legal lengths in the two countries in the past, provided the opportunity for avoidance of size controls by illegal transfer across the border. In its 1994 CITES proposal for C. porosus, Indonesia proposed bringing the upper size limits for wild skins of both species into concurrence at 51cm belly width, although the lower limits remained different. Harvest analysis data from Papua New Guinea suggest that between 40% and 75% of nesting C. novaeguineae, as well as some nesting C. porosus are smaller than this size and are thus subject to harvest (Hall 1991b, Hall and Johnson 1987, Montague 1983, 1984, Cox 1985). The smaller lower size limit in Papua New Guinea may be biologically defensible, but it is economically wasteful due to the low prices offered for such size hides.

Priority projects

High priority

Implementation and enforcement of crocodile management regulations in Indonesia: An external review of the Indonesian crocodile management program, conducted by Webb and Jenkins (1991a), provided specific guidelines for restructuring the existing program. The recommendations were incorporated into the proposals for crocodile management in Indonesia and form part of the Indonesian proposal for CITES Appendix II listing of its C. porosus population. Continued action is needed to develop and implement this program and to assist Indonesia in establishing workable regulatory mechanisms for using its New Guinea crocodile resources.

Moderate priority

Standardize harvest size limits between range states at biologically optimal sizes: Different size limits for trade in crocodiles remain in the two neighboring range states. Both states should review existing data, conduct any necessary additional studies, and adopt a size limit that ensures sustainable use, protects the breeding stock and encourages sound economic use of the resource.

Continued population monitoring and analysis of exploited crocodile populations: Both Indonesia and Papua New Guinea should undertake the collection, collation and analysis of survey data with a view to deriving cost-effective long-term monitoring programs that can be sustained by the government and the industry, and which will determine the extent to which the harvest is sustainable.

New Guinea crocodile, Crocodylus novaeguineae, Saint Augustine Alligator Farm, Florida,
USA. Photo by B. Shwedick.