Senin, 15 November 2010

Incidence of Fish Hook Ingestion by Komodo dragons

Incidence of Fish Hook Ingestion by Komodo dragons

Tim Jessop1, Jeri Imansyah2, Deni Purwandana2, Achmad Arifiandy2 and Devi S. Opat3
1Department of Wildlife Conservation and Research, Zoos Victoria, PO Box 74 Parkville VIC 3052, Australia
2 Komodo Dragon Species Survival Program Indonesia, Denpasar, Bali, Indonesia.
3 Taman National Komodo, Labuan Bajo, Flores, NTT, Indonesia.
Correspondence to Tim Jessop
(e-mail: tjessop@ zoo.org.au).
The Komodo dragon (Varanus Komodoensis), a large robust monitor lizard, persists on the 5 islands in Eastern Indonesia (Ciofi and deBoer 2004). The waters surrounding these islands are intensively utilized for marine resources and in particular line and net fishing are prolific. For other reptiles, particularly freshwater and marine turtles, incidental injury and mortality through ingestion of fishing hooks during routine foraging activities are not uncommon (Polovina et al. 2000). However, similar incidents of reptile by-catch in terrestrial species is poorly documented even though, many large lizards such as monitors, are semi-aquatic or cohabit and forage within coastal areas in which intense fishing activities persist. Here we report two incidents of ingestion of fishing gear by Komodo dragon during routine monitoring of island populations between 2002- 2006.
Annual mark recapture studies were conducted at 10 sites across 4 islands within Komodo National Park during both 2002 and 2005 and resulted in 827 dragons captures(> post-hatchling size). From this sample, 2 cases of fishhook ingestion were reported. The first case, comprised a small monitor (Animal ID: 00063A9978, 69.35 cm SVL, 7 kg) captured at Loh Buaya (8:39:21.7 S, 119:43:06.2 N) on Rinca Island and appeared to occurred recently as the line protruding from its mouth was still relatively long and the nylon in good condition. Based on the line weight it is suspected that the hook ingested by this lizard was relatively small. This lizard was recaptured in 2005, without any evidence of the protruding fishing line (however if the hook was remaining is unknown) and it had grown 8.75 cm in SVL and increased its mass by 1.45 kg. The second lizard, an adult male (Animal ID: 000643A7EC, 127.75 cm SVL, 41.8 kg) was captured on the 19th June 2004 also from Rinca Island at Loh Tongker (8:45:31.1 S, 119:42:57.3 E) a small coastal valley on the south east coast. In this incident the hook ingested was likely to have been considerably larger and typical of those used for capturing large pelagic species on long line. This hook was shackled with 2 strands of heavy trace wire (Fig 1). In this instance it is believed the hook was ingested several weeks to months earlier as indicated by the lesion induced by abrasion from the trace wire. In 2005, this adult male was recaptured, there was no evidence of the protruding trace, however it was not known if the hook still resided within the animal. The weight of this male had decreased by 8.8 kg from 2004 and 20 kg from its first capture in 2003 despite growing relatively little in length (4 cm in SVL).
Consumptions of fishing hooks by Komodo dragons, albeit rare, is a likely consequence of these lizard’s prodigious scavenging capacity coinciding with discarded fishing gear that finds it way into the intertidal areas exposed on the low tide. As yet we do not know what effects hook ingestion might incur for the specific individuals dragons, however, given that mortality occurs readily in other reptiles, it is possible that at least in the case of the second animal there may be negative consequences.
References
Ciofi, C. & de Boer, M.E. 2004. Distribution and conservation of the Komodo Monitor (Varanus komodoensis). Herpetological Journal 14: 99-107.
Polovina, J.J., Kobayashi, D.R., Ellis, D.M., Seki, M.P., & Balazs, G.H., 2000. Turtles on the edge: Movement of loggerhead turtles (Caretta caretta) along oceanic fronts in the central North Pacific, 1997-1998. Fisheries Oceanography 9(1):71-82.

Scientists discover deadly secret of Komodo’s bite

Scientists discover deadly secret of Komodo’s bite
AFP
Scientists discover deadly secret of Komodo’s bite AFP/File – The world’s largest lizard, the Komodo dragon, has a snake-like venom in its bite which sends victims …
Tue May 19, 3:31 am ET
SYDNEY (AFP) – The world’s largest lizard, the Komodo dragon, has a snake-like venom in its bite which sends victims into shock and stops their blood from clotting, according to Australian research.
It had been widely believed that deadly bacteria in the carnivorous lizard’s mouth helped kill its prey.
But magnetic resonance imagery has for the first time uncovered venom glands containing a shock-inducing poison which increases blood flow and decreases blood pressure, scientists say.
Lead researcher Bryan Fry said three-dimensional computer imaging comparing the Komodo’s bite with that of Australia’s saltwater crocodile showed it used a “grip and rip” pulling manoeuvre to tear deep wounds, similar to a shark or sabre cat.
Fry surgically removed a venom gland from a terminally ill Komodo at Singapore Zoo for the study, and said it contained a highly toxic poison which would induce potent stomach cramps, hypothermia and a drop in blood pressure.
The venom also blocked the blood’s clotting ability, he said.
“Such a fall in blood pressure would be debilitating in conjunction with blood loss and would render the envenomed prey unable to escape,” he said.
“These results are congruent with the observed unusual quietness and apparent rapid shock of prey items.”
Komodos are the world’s heaviest lizard, typically weighing 70 kilograms (150 pounds) and growing up to three metres (10 feet) in length.
They are native to several Indonesian islands and are considered a vulnerable species, with only a few thousand left in the world.
They live on a diet of large mammals, reptiles and birds but have been known to attack humans.
An Indonesian fisherman was in March mauled to death by a Komodo dragon after he ventured into a remote island sanctuary for the giant killer lizards
Sumber: http://news.yahoo.com/s/afp/20090519/sc_afp/scienceanimalkomodoaustralia_20090519073836

About Komodo Island,,,,,

Komodo is one of the 17,508 island that make up the Republic of Indonesian. The island has a surface area of 390 km² and over 2000 inhabitants. The inhabitants of the island are descendants of former convicts who were exiled to the island and who have mixed themselves with the Bugis from Sulawesi. The population are primarily adherents of  Islam but there are also Christian and Hindu minorities.

Komodo is part of the Lesser Sunda Chain of islands and forms part of the Komodo National Park. Particularly notable here is the native Komodo Dragon. In addition, the island is a popular destination for diving. Administratively, it is part of the East Nusa Tenggara Province.

Location ;  Komodo lies between the substantially larger neighboring islands Sumbawa to the west and Flores to the east.

Fauna ;  The island is famous not only for its heritage of convicts but also for the unique fauna which roam it. The Komodo Dragon, the world's largest living lizard, takes its name from the island. A type of monitor lizard, it inhabits Komodo and some of the smaller surrounding islands.