Meandering the Mighty Mekong, in search of a fin

“Yes, there they are!” A deep sigh, and a grey back elegantly curves out of the water, to bow just as smoothly out of sight again. Right behind follows a second one. The ease of the movement and the surprise of the appearance both thrill me.

Meeting the Giant
I am sailing the mighty Mekong in Cambodia. Sitting cross-legged on the bottom of a boat hardly bigger than a canoe, we navigate the flooded forests; a spectacular landscape, especially when viewed from this frog-perspective. Our captain is a master of these shallow waters, steering under trees, alongside rocks and over rapids that would have caused me clammy hands if I had been in my canoe. But our skipper knows his river.

After the forests, the vastness begins, and I am captured by the wideness of this river. Living on the shore of the biggest river of northeast Europe, I now must acknowledge that the Rhine is just a minnow compared to the Mekong. A 10 km wide river bed with islands 40 km long - this scale is astonishing.

Bending the curve
This is where the Irrawaddy dolphin lives, one of the five fresh water dolphins of the world - and I just saw two of them! They are social creatures, hanging out in the deep ‘pools’ of the Mekong river, spots where the river bed suddenly plunges to 20 meters depth. The last survey in 2017 counted 92 Mekong dolphins. That number evoked quite a party: compared to the previous count, 80 individuals in 2015, for the first time we saw an increase. After a decade-long decline, the curve was bend! Indeed, worth a celebration. But, let’s be honest: 92? Is that a viable population?

During our 8-hour boat trip, we observe around 20 fishermen in small boats like ours, flinging their nets into the water. Observing this small-scale hard work, it is difficult to believe that fishing is the main cause of death of river dolphins. And indeed, the fishermen we see in the day time are not the real threat. More lethal are the pool fishers, working mostly at night and using gill nets – nets with a very small maze; too small for the dolphin to detect with their sonar system. If a dolphin gets entangled in such a net beneath, it simply drowns; unable to come up for air. Fishing in these pools is forbidden, as are the gill nets - but the deep pools also attract the large fish, so it is tempting to break the law.…

River guards and river diseases
The recent increase in dolphin numbers is thanks to river guards, community patrols that fight illegal fishing, supported by WWF. This works very well, and it is expected that the positive trend continues: since 2017, observed newborns have outnumbered deaths. But at the same time, the sword of Damocles hangs over the Irrawaddy dolphin and many other unique species that live in the Mekong.

Dams. Those damned dams. While I am sailing the Mekong, the water levels are the lowest ever observed. And the dry season has only just begun, with three more dry months to come. The continuous water need for energy production in upstream countries Laos and China, leaves very little water for the river and its functions downstream. Knowing that the Mekong boasts the second highest level of biodiversity in the world (after the Amazon), this is bad news for species richness. As species withdraw into the refuges of the ‘deep pools’, many fishermen will do the same. The river guard patrols will be needed more than ever.

Puzzled
My first encounter with a river dolphin leaves me puzzled. I feel enriched by the experience to have been near this elegant creature, the top predator of this giant river system. But I am worried about its future – and with his future, the future of many other species and the millions of people that depend on the Mekong for their lives.