24 August 2011

Will there be any dugongs 100 years from now?

Professor Helene Marsh, the leading authority on dugongs, gave a public lecture on "Challenge of conserving dugongs in our region". 
She outlined some aspects of the rather dire situation that dugongs face today. Dr Elizabeth Taylor also shared about Singapore's wild dolphins.


In the biodiversity crisis we face today, Prof Marsh explained, the three orders of mammals at risk of extinction include the Order Sirenia to which the dugongs belong. The Order includes 3 species of manatees which are found in the Americas and Africa. While the dugong is found in our part of the world from the Horn of Africa to Australia. The manatee has a paddle shaped tail, while the dugong has a tail like a whale. Prof Marsh added that the dugong is more 'svelte' and is what a manatee would look like if it goes to the gym!
Humans have already killed off an entire species in Sirenia. The Steller’s sea cow (Hydrodamalis gigas) was hunted to extinction within 27 years of its discovery in the eighteenth century. It was an awesomely huge animal and we ate it out of existence.
Sadly, the same fate threatens the dugong. Apparently dugong is also very tasty! Somewhat like high quality beef, we learn.
Of all the Sirenia, dugongs are the only ones to feed solely on seagrasses. The other manatees eat all kinds of other plants. One was even said to have eaten a rat!
Dugongs take a long time to digest their food. They have very very long intestines, at 30m long. Humans only have 1m of guts. This is why they are such slow and placid animals.
Not only are dugongs tasty AND slow-moving, tragically, they also hang out in places which are very accessible to humans.
Prof Marsh highlights that dugongs can be found wherever there is seagrass, even in relatively built up areas. And among the examples, Prof Marsh has chosen to use our photo of a dugong feeding trail at Chek Jawa in 2007, with Wei Ling in the photo!
Dugongs can live for decades, take a while to reach sexual maturity and don't breed rapidly.
All these realities mean that we really can't afford to lose many dugongs to human kills. Prof Marsh outlines this rather sobering chart. In Singapore, we would be lucky to have 100 dugongs. And even if we have 100 dugongs, we can't afford to lose a single one if we want to have a sustainable population!
Most dugong territory lie in underdeveloped countries with poor people living on the coastline. To these hungry people, dugongs are worth more dead than alive. Dugongs are hunted for their meat and their ivory and bones are used in traditional craft.
Dugongs are also affected by fishing including the destructive bomb fishing.
Meanwhile, in developed countries, dugongs face threats of boat strikes and coastal development. Prof Marsh also chose to use the photo of the dead dugong that washed up on our Pulau Tekong in 2006 in this slide.
Prof Marsh shared how one of her studies found that in Queensland, there has been a 97% decline in dugong numbers variously related to agricultural pollution, vessel traffic, subsistence hunting and gill and shark netting.

Prof Marsh then highlights an issue that I find fascinating. The idea that conservation of cultural diversity is very important to conservation of dugongs. She showed how the areas where biocultural diversity is at greatest risk (red) overlaps with the natural distribution of dugongs!
She then introduced us to the Dugong Capital of the World: Torres Strait. Here, dugongs are very well embedded in the local culture and lifestyle. Dugongs are part of the cuisine too.
In fact, dugongs have been hunted here for 4,000 years! This dig of a midden had remains of 10,000 to 11,000 dugongs!
And here's something else I learnt. Apparently the traditional way to hunt dugong is to set up a platform near a feeding trail and then wait for the dugong to come back. Hmm, maybe this is one way we can get sightings of dugongs on our seagrass meadows? But someone must be willing to sit on the platform and wait....
More recently though, traditional hunters have started to use motorised boats to hunt dugongs. And thus there is the question of whether traditional hunting remains sustainable.
Prof Marsh also shared more of the threats and pressures facing dugongs elsewhere. Such as at Mozambique. Where the people are so poor they are willing to illegally hunt sharks and if they catch a dugong by the way, they will also kill it. One dugong represents several months' wages. The situation is the similar in Papua New Guinea where dugongs are an important source of food for impoverished people.
Prof Marsh reveals a final grim picture. Given the pressures, it is likely that dugongs will only continue to exist in a few countries.
Conserving dugongs require education, enforcement and monitoring, as well as efforts to reduce human caused deaths, conserving the habitat and providing alternative livelihoods to people who would otherwise eat the dugongs.
Read more in Prof Marsh's IUCN DugongStatus Report and Action Plans forCountries and Territories (pdf). She also informed that her new book is due out later this year. It is already listed on Amazon: Ecology and Conservation of the Sirenia: Dugongs and Manatees. How exciting!

Before Prof Marsh's talk, Dr Elizabeth Taylor shared about the Singapore Wild Marine Mammal Survey (SWiMMS) programme to learn more about Singapore's marine mammals.
It seems we basically have 4 different kinds of cetaceans. Dr Taylor explains how to tell them apart. Here's a earlier post with more on how to tell apart Singapore's wild marine mammals.
I learnt from her that the 'Pink' dolphin can indeed be bubble gum pink. Although in colder waters further north they might be white. But the baby is usually grey and looks a little like a bottlenose dolphin.
I didn't know Singapore waters is home to the Irrawaddy dolphin too! More about these and other marine mammals of Singapore on the SWiMMS page.
She also shared some photos of dolphins seen in our waters.
If you spot a dolphin, porpoise, dugong, whale in Singapore waters, do fill up their online sighting form. SWiMMS has a website of latest sightings and a map of these sightings. I see from this site that on 18 Aug 2011, 2-3 Indo-Pacific humpback dolphins were seen near Pulau Tekong!

After the talk, since we were already at the zoo and near the enclosure, a few of us dropped by to take a look at the manatees there. Observe, NOT dugongs.
See, it has a paddle-shaped tail.
Singapore has wild dugongs! We have been seeing their feeding trails at Changi in May 2011 again in May 2011, Chek Jawa in Apr 2011 and Jul 2011 and even in Semakau in May 2011. More about dugongs in Singapore with links to sightings of dugong feeding trails.

Want to help protect the dugongs? Join TeamSeagrass, a group of volunteers who monitor the dugong's food!

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