The fate of the false gharial

The peat swamps of Southeast Asia have received slightly more attention (though sadly little action) recently, thanks to their treasury of minuscule fishes. But there is also another, far larger, creature whose survival hinges on the preservation of these blackwatered wetlands.

Reaching up to 6 metres in length, the estuarine or saltwater crocodile (Crocodylus porosus) is the largest living reptile. This leviathan ranges from Southeast Asian rivers all the way to the billabongs of northern Australia, consuming everything from turtles to tourists. Despite considerable human persecution (tales of which can attain mythical undertones), the saltie remains little threatened by extinction. Local populations in Southeast Asia are likely to be at historic lows, but this crocodile's ability to transverse marine gulfs and broad adaptability to different habitats (including Singapore's reservoirs and mangroves) render it a resilience that has withstood the encroachment of man on its turf and for its hide.

The salties' cousin, the false gharial (Tomistoma schlegelii), faces a rather less certain future. This crocodilian ranks as another true giant, attaining a length of about 5 metres. Mandai Zoo, if I recall correctly, boasts a few specimens of immense proportions. Unlike the estuarine crocodile, the false gharial is no man-eater. Its relatively slender jaws (which resembles those of the true gharial, Gavialis gangeticus) from India) are built for capturing fish and other aquatic creatures whole, rather than ripping into the flesh of terrestrial vertebrates.

Studies on the ecology and distribution of false gharials are as scarce as the animals themselves, so a newly-published paper by Robert B. Stuebing et al. in the Raffles Bulletin of Zoology offers a valuable status report on this little-known giant. Echoing the discoverers of Paedocypris progenetica, the paper highlights the sad plight of the region's peat swamps. Less than 50% of Borneo's peatlands, for instance, remain intact, as a result of logging, swamp reclamation and forest fires.

Stuebing's work involved a tabulation of sighting records of false gharials based on museum specimen data, field observation by the authors, and first-hand sightings by collectors and local people. Second or third hand information was discounted. Records dating from 1838 to 2004 produced a rather low number of 210 sightings, while a total of 180 records were compiled for the period 1980 - 2003.

Eastern Sumatra from southeast Aceh to Lampung Provinces appear to be historical strongholds for the species, although the authors note that extensive crocodile hunting from the 1950-60s and large-scale swamp clearing activities from the 1960s are likely to have significantly influenced T. schlegelii distribution and abundance after 1940. The species is noted to be probably locally extinct or very rare in many parts of Lampung, North Sumatra and Aceh.

Western and Central Kalimantan (up to the uppermost parts of Sungei Barito north of Muara Teweh) are also known to be key habitats, while in Sarawak, most sightings came from the upstream areas of the Sadong and Lupar rivers. Tasek Bera in Peninsular Malaysia is a reputed locale, although the authors found no evidence during a 2-week survey. Confirmed sightings are known from Sungei Perak as well as the Bahau district in Negri Sembilan, and the paper notes a case in 2002 where at least one specimen was caught and sold to a restaurant in Bahau.

T. schlegelii is believed to have enjoyed a wide distribution in Sundaland during the Pleistocene era, when the region was high and dry and interlinked by the mighty Sunda River basin and its now sunken adjoining peat swamp flood plains. The authors note that T. schlegelii is a peat swamp specialist, preferring slow-moving water bodies rather than rivers with strong currents.

In present day Southeast Asia, the species' populations are fragmented and appear to be largely confined to a region about 5 degrees north and south of the equator. The authors write that populations in Sumatra and Peninsular Malaysia are under heavy pressure from burgeoning human populations and land development, leaving Sarawak and Kalimantan as the species' last stronghold. It would appear that the false gharial is not uncommon in many crocodile farms, but these captive specimens are not likely to have much value for reestablishing wild populations, given their uncertain origins and the loss or degradation of suitable habitats.

The creature's cryptic habits and effective camouflage render it a difficult subject, as the authors note with caution, stating that their field surveys in areas where T. schlegelii is known to occur have often resulted in zero sightings. In some rivers in Central Kalimantan, the species appears to be actually abundant, while Perak State and Lake Kenyir in Peninsular Malaysia harbour small breeding populations.

Practices that threaten the survival of T. schlegelii include forest fires, hunting, illegal logging and clearing of swamps for agriculture and mining. In Sarawak, the draining and 'straightening' of peat swamp tributaries that feed Sungei Sadong has reduced the area's once abundant population. T. schlegelii is currently classified as 'endangered' by the IUCN.

In conclusion, the authors recommend a conservation approach that focuses on population monitoring efforts in key areas of local abundance and habitat suitability. These include Sungei Merang and Berbak National Park in eastern Sumatra; the Tanjung Puting National Park in Central Kalimantan; Sungei Sibau and Gunung Palung National Park in West Kalimantan; and the Lingga-Simunjan area and Maludam Wildlife Sanctuary in Sarawak. With hope, this gentle giant will not share the fate of its  distant cousins, the Chinese alligator, Philippine crocodile and Siamese crocodile, which now cling to existence by the skin of their teeth and may well join the ranks of the dinosaurs whose era they outlived.

Philippine crocodile (Crocodylus mindorensis) by Zhou Hang.

Stuebing also suggests the identification and classification of sites using geological maps to find old, low lying alluvial basins that contain peat swamp remnants or blackwater forests where T. schlegelii might be found along with "some fairly distinct vertebrate communities". Here, he cites a paper on peat swamp frogs. I would have liked more information on this observation, but unfortunately, he's already left Singapore, it seems, after a brief but productive stopover.

Comments

[dearkitty]

Hi, more on false gharials and other crocodilians here.

[monkey]

we just saw the false gharail at the zoo 2 days ago!

[budak]

never take pic ah!?? Or only take pics of monkies!??

[monkey]

of course got take picture lah! :P