The breeding data

Nesting in the Northern Territory rivers (Daly River and Alligator Rivers) occurs sooner than nesting in the rivers of Irian Jaya and New Guinea, which is related to the climate differences between the two regions*.

* The differences between the climates are described at the Habitat section.

The table 1 shows the occurrence of nesting season in both regions:

Table 1

* Because some eggs appear in the Kikori markets as late as February (Groombridge, 1982), the nesting season may last until the end of January.

"Bimodal distributions of nesting dates both in the Kikori District of Papua New Guinea and the Daly River of Australia provides strong evidence of multiple clutching (see also Legler, 1980), a conclusion supported by examination of reproductive tracts of three specimens dissected during the nesting season at Kikori (Rose, unpublished data)."

"Carettochelys typically chooses clean fine sand adjacent to water in which to nest (Cann, 1978, Pernetta and Burgin, 1980; Legler, 1982; Webb et al., 1986; Rose, pers. obs.), but also nests in mud and loams at some localities (Slater, 1961; Cogger, 1975: Plate 59 and pers. comm.; Groombridge, 1982; Rob Elvish, pers. comm.; Rose, pers. obs.) It nests upon sand banks adjacent to water in the middle reaches and mouths of rivers, on sandy shores of islands in river deltas, and on coastal beaches (Rhodin and Rhodin, 1977; Groombridge 1982; Webb et al. 1986; Georges and Kennett 1989)."

Carettochelys insculpta has been reported to nest in the rivers which are included in the table 2.

Table 2

The eggs are white, hard-shelled and almost quite round (Ramsay, 1886). The table 3 shows the mean egg diameter, mean egg weight, clutch size, incubation period, hatchling length and weight data according to several locations.

Table 3

Carettochelys insculpta is like many other aquatic turtles a temperature-sex-dependent species. "The hatchling sex ratio of Carettochelys insculpta is influenced by the temperature that prevails during incubation, both under constant conditions in the laboratory (Webb et al., 1986) and under fluctuating conditions in field nests (Georges, 1987; Georges, submitted)." The eggs that are incubated at a constant 28-30°C produce males while those incubated at 32°C produce females (Webb et al., 1986). "The laboratory threshold for sex determination is not known precisely (between 30°C and 32°C Webb et al., 1986), but under field conditions, the threshold of 31.6°C (Georges, 1987) agrees very well with the average nest temperature in New Guinea of 31.6°C (Rose, unpublished data)".

There is no information on how long it takes for a young turtle to reach maturity. Though based on some laparoscopy work and the keeping of specimens from hatching it would seem that it takes 25 years for this species to reach maturity (Thomson, pers. data)

According to my knowledge, there is no organization or person that has managed to successfully breed this species in captivity, but Oliver Römpp has written to me that captive breeding occurred at both the Bronx ZOO, NY, USA and the Zoological Garden Wilhelma, Stuttgart, Germany. For more information please see Oliver's section about Carettochelys at http://www.chelodina.com/10.htm.