Endangered River Dolphin Species’ Numbers On the Rise | National Geographic

[Lindsay] Within the last couple of decades, this population has dramatically decreased in number. (camera clicks) There is one really close. (camera clicks) (gentle music)

They are incredibly challenging to study because when they do surface, they don't bring much of their bodies out of the water. So, it's difficult to identify individuals, and it's difficult to really discern what type of behavior is occurring. (gentle music)

[Lindsay] For photo identification of individual dolphins, for many, many species, we use the shape or the coloration that you find on the dorsal area, particularly the dorsal fin. The main cause of mortality for this species, previously, was entanglement in gillnets. The river guard program was put in place to remove the illegal gillnets which are being set on the dolphin sanctuary areas. So, the chances of dolphins becoming entangled in these nets, of course, are far less if they simply aren't there. (gentle music) (boat running)

[Lindsay] We're quite hopeful because we've seen a decrease in adult mortality, and there are several new calves in the last two years as well. The last population estimate was for 92 individual dolphins in the area, and that's an increase of 12 from the previous estimates. So, we're very hopeful that this population is now on the road to recovery.

[Lindsay] I think one of the most spectacular things about this particular population is the setting itself. They are such an integral part of the communities that live around the river. The people that live in the Mekong area rely entirely on the river habitat as do the dolphins. The dolphins and the humans, it's all part of one big system that's really clear to see. (gentle music)