Mekong river dolphin on the verge of extinction

Adam Khor

Dolphin population in the Mekong may not be greater than 85, says a new study.

Mekong dolphins are not a separate species, but a population of the Irrawadi Dolphin (Orcaella brevirostris), said by experts to be the closest relative to the Killer Whale.
Unlike their most famous and abundant cousins, Irrawadi Dolphins are small (max. 2.75 meters long), feed mostly on fish and prefer fresh and brackish water over oceanic habitat.

Several fresh water cetaceans are greatly endangered today- the Baiji as you may remember became the first cetacean species to become extinct because of the action (or lack of action?) of man in 2006 (with maybe a very few of them surviving, but almost certainly not enough to revive the species).

Experts fear that the next in line could be another of the river dolphins, or perhaps the Vaquita, a porpoise endemic to the Gulf of Mexico whose total numbers may be lower than 250.

Mr. Boo

The Vaquita is barely hanging in there, and it does not look good as I believe there is still no ban on gill net fisheries, and poor regulation of pesticide and nutrient run-off. It also has a pretty limited distribution to further complicate matters. I think the Irrawaddy has a comparatively large distribution, but not doubt its status is still threatened.

My question is, as I have heard many people I respect on the matter give fairly significantly differing figures, but what sort of numbers does a population like this need to retain genetic diversity to keep it from becoming functionally extinct?

Adam Khor

Mr. Boo wrote: »

The Vaquita is barely hanging in there, and it does not look good as I believe there is still no ban on gill net fisheries, and poor regulation of pesticide and nutrient run-off. It also has a pretty limited distribution to further complicate matters. I think the Irrawaddy has a comparatively large distribution, but not doubt its status is still threatened.

My question is, as I have heard many people I respect on the matter give fairly significantly differing figures, but what sort of numbers does a population like this need to retain genetic diversity to keep it from becoming functionally extinct?

I'm no expert, so I really don´t know... I guess if the population has no contact at all with other Irrawadi dolphins from other places, its genetic diversity may already be compromised regardless of the numbers...

Yes, the Irrawadi has a larger distribution- it is the Mekong population that's about to dissappear.

Mickeroo

Is there any plans to maybe relocate some from the areas with healthy populations?

ILikeBananas

I went on a dolphin spotting trip on the Laos-Vietnam border back in 2008 and we found it incredibly hard to find any dolphins. The guide was saying that every year it gets more and more difficult.

Adam Khor

ILikeBananas wrote: »

I went on a dolphin spotting trip on the Laos-Vietnam border back in 2008 and we found it incredibly hard to find any dolphins. The guide was saying that every year it gets more and more difficult.

Did you find them, though?

ILikeBananas

Adam Khor wrote: »

Did you find them, though?

Hard to say. We saw something about 500m away flash out of the water and disappear again. The guide said it was a dolphin. Could have been anything really but yeah it probably was one.