Carettochelys insculpta Ramsay 1886 – Pig-Nosed Turtle, Fly River Turtle

Abstract

summAry. -Carettochelys insculpta, the pig-nosed turtle (Family Carettochelyidae), is the sole surviving member of a family of turtles that was widely distributed during the Tertiary. It is restricted to the southern rivers of New Guinea and the rivers of the Northern Territory in Australia. Carettochelys is therefore a distinctive geographic and taxonomic relict and, although locally abundant, it is rare in the sense of being geographically restricted. Moreover, Carettochelys is unique or unusual among turtles in many facets of its morphology, ecology, and behavior. Populations in New Guinea are thought to be declining because of increased exploitation for meat and eggs for both domestic consumption and the international pet trade. This exploitation has been exacerbated in recent times by the introduction of modern technology, principally outboard motors. In addition, clan warfare has ceased, and people have moved from the hinterland to more convenient locations along river banks. Moreover, levels of commercial activity such as logging, mining and exploration for oil, gold, and copper and fishing have increased in recent times, bringing larger human populations, both indigenous and non-indigenous, into closer contact with turtle populations. In Australia, feral animals have posed a threat through widespread trampling of nesting banks and destruction of riparian habitat. Other potential pressures include aggressive pastoral and agricultural practices that push the land in the important catchments beyond capability. Such agricultural development, if not accompanied by appropriate and effective land management, can result in erosion, destruction of riparian vegetation, siltation of water courses, reduction and altered timing and duration of dry season environmental flows, which can lead to gross degradation of riverine habitat as we have seen in the southern states of Australia. Urgent research is required to determine trends in population numbers and levels of exploitation in New Guinea, and to identify and implement management options for the sustainable exploitation of Carettochelys. In Australia, improved knowledge of the distribution of Carettochelys is required, especially the status of populations in the Victoria River, so that the value of the two known major populations in the Daly River and Alligator Rivers region can be adequately assessed. Wet-season habitat requirements, extent of seasonal movements, and requirements of juveniles are unknown, yet this information is needed to gauge the possible impact of proposed or potential development within catchments and to gauge the adequacy of existing reserves for protecting the species.

Salinity of the coastal nesting environment and its association with body size in the estuarine pig‐nosed turtle

“…Data on the size of female C. insculpta nesting were recorded from harvested individuals in 37 villages and associated White circles represent recorded observations; grey shading is the projected distribution; populations that have been the subject of study are delineated by dotted lines (Daly, South Alligator, Kikori and Purari). Adapted from Georges et al (2008b). fishing camps across the region. When shells or live turtles were available, we measured the curve carapace length (CCL) and information was sought on the locality of capture.…”

“…Primarily a freshwater group, many species of softshell turtles (Trionychidae) nest and occupy estuarine or even marine habitats (Pritchard, ). Its sister family, Carettochelyidae, comprises one single living species, the pig‐nosed turtle Carettochelys insculpta , which also occurs and nests in coastal areas of southern New Guinea (Rhodin & Rhodin, ; Georges et al ., 2008 a , b ). Female C. insculpta nest in large numbers on coastal beaches and isolated sandbanks of the Gulf of Papua, at the mouth of the Fly, Kikori, Omati and Purari Rivers (Pernetta & Burgin, ; Georges, Guarino & Bito, ; Georges et al ., 2008 a , b ).…”

“…Its sister family, Carettochelyidae, comprises one single living species, the pig‐nosed turtle Carettochelys insculpta , which also occurs and nests in coastal areas of southern New Guinea (Rhodin & Rhodin, ; Georges et al ., 2008 a , b ). Female C. insculpta nest in large numbers on coastal beaches and isolated sandbanks of the Gulf of Papua, at the mouth of the Fly, Kikori, Omati and Purari Rivers (Pernetta & Burgin, ; Georges, Guarino & Bito, ; Georges et al ., 2008 a , b ). However, coastal nesting does not occur in Northern Australia, where populations are restricted to the upper parts of the rivers (Georges & Kennett, ; Doody, Georges & Young, 2003 a ; Doody, Sims & Georges, 2003 b ; Doody, West & Georges, 2003 c ; Georges et al ., 2008 b ).…”

“…Its sister family, Carettochelyidae, comprises one single living species, the pignosed turtle Carettochelys insculpta, which also occurs and nests in coastal areas of southern New Guinea (Rhodin & Rhodin, 1977;Georges et al, 2008a,b). Female C. insculpta nest in large numbers on coastal beaches and isolated sand- (Georges & Kennett, 1989;Doody, Georges & Young, 2003a;Doody, Sims & Georges, 2003b;Doody, West & Georges, 2003c;Georges et al, 2008b).…”

The shell bone histology of fossil and extant marine turtles revisited

“…flippers are also present in Carettochelys insculpta , which mainly lives in lotic habitats, i.e. river and estuarine systems in New Guinea and Australia: Waite, ; Georges et al ., ) and thus a combination of indicators is more reliable.…”