Irrawaddy Dolphin Extinct In Laos; Last Individual Died From Entanglement,Lacerated Tail

[hatrack]

Known only by his identity code, ID#35 was the last individual of a doomed subpopulation of freshwater Irrawaddy dolphins (Orcaella brevirostris). He was the sole occupant of a deep pool in the Mekong River that spans the border between Cambodia and Laos, and fought for several weeks against lacerations to his tail from entanglement in illegal fishing gear. He had been struggling to swim, let alone to feed himself.

Mortally wounded, ID#35 died as many of his kin before him. Yet there was a deeper significance to the moment his pale and bloated body washed up on a riverbank in mid-February 2022: his death confirmed that the Irrawaddy dolphin is extinct in Laos.

Cetacean specialists have documented the loss of the dolphins from the Chheu Teal transboundary pool for years. In 1993, there were 17 individuals living in the pool. By 2009, the subpopulation had dwindled to seven; three years later to six; and by 2018, only three remained. In 2021, photo identification surveys led by Cambodia’s Fisheries Administration and WWF confirmed that ID#35 was all alone.

The species, found in both freshwater and marine environments in South and Southeast Asia, is considered globally endangered. However, the freshwater populations that inhabit the Irrawaddy in Myanmar, the Mahakam in Indonesian Borneo, and Cambodia’s stretch of the Mekong are critically endangered, each with fewer than 100 remaining individuals. With the loss of the Mekong’s Chheu Teal subpopulation, the river’s fewer than 90 surviving dolphins now exclusively occur downstream in Cambodia, where they face the same range of threats that wiped out the transboundary group.

EDIT

https://news.mongabay.com/2022/04/death-of-last-river-dolphin-in-laos-rings-alarm-bells-for-mekong-population/

[jfz9580m]

1. On a related note

It doesn't get anywhere near as much attention as various non-issues do but the sixth mass extinction seems to be approaching rapidly:
https://evolution.berkeley.edu/mass-extinction/the-earths-sixth-mass-extinction/

The Earth’s sixth mass extinction?
As human populations have grown and become more technologically advanced, we’ve taken a larger toll on the rest of the natural world. We’ve encroached on (and sometimes wiped out) the habitats of other species; we’ve released pollutants into the air, soil, fresh water, and oceans; and we’ve even changed the atmosphere and climate. These changes are beginning to disrupt Earth’s systems at global scales — and are occurring rapidly. Because of our burning of fossil fuels, carbon dioxide levels are rising faster than they ever have at any point in Earth’s history.10 It’s no surprise then that extinction rates have risen substantially in the last 500 years.

In this module, we’ve seen that mass extinctions also involve a sharp increase in extinction rates over normal levels. So how bad is our current situation? Have humans pushed the Earth into its sixth mass extinction? The answer appears to be, “Not yet.” But we are currently losing species at a rate far higher than normal background extinction rates, and the situation is dire. We are rapidly approaching a loss of diversity similar to that seen during mass extinctions. Biologists predict that unless we change course and begin preserving more species, within the next few hundred years, we will become the cause of Earth’s sixth mass extinction.11

The good news is that we can stop this mass extinction. While there’s no way to deflect an unforeseen asteroid strike or put a plug in a volcanic eruption, the current extinction rate is being pushed ever higher by human activity — and that means that human activity can also reverse this trend. We can reduce the extinction rate through policy changes that increase conservation efforts and curb our production of greenhouse gases to slow climate change. Studies of the Earth’s history may play a surprisingly important role in this effort. If we can understand the chain of events that led to past mass extinctions, we will be in a better position to break that chain today. And if we can understand what traits make a species particularly vulnerable during a mass extinction, we may be able to better focus our conservation efforts. Investigating Earth’s past extinctions may be one of the keys to preserving biodiversity for the future.