Indus river dolphin's declining range

Jul 16, 2014
Indus River dolphins. Credit: Albert Reichert

Removal of river water for irrigation and habitat fragmentation by irrigation dams were shown to be the principal factors contributing to the decline of the Indus river dolphin, according to a study published July 16, 2014 in the open-access journal PLOS ONE by Gill Braulik from the Wildlife Conservation Society and University of St. Andrews and colleagues.

Many freshwater marine mammals are endangered due to rapidly degrading habitat and conservation of these megafauna species depends on maintaining intact habitat. This study used historical range data and information on dolphin presence from fisher interviews to better understand the timing pattern of range decline of the Indus River Dolphin, an endangered freshwater dolphin that inhabits one of the most modified rivers in the world. Additionally, the authors' modeled seven potential explanations of declining range, including date of construction of the nearest , dry season , distance from the edge of the former range and length of river section to identify the factors responsible for the decline.

Results indicate that the historical range of the Indus dolphin has been fragmented into 17 river sections by diversion dams. River dolphins disappeared from ten river sections, still live in six, and are of unknown status in one section. Scientists found that low dry-season river discharge, due to irrigation at diversion dams, was the principal factor that explained the dolphin's range decline and that dolphins were more likely to persist in the core of the former range, likely due to the concentration of water diversions and dams near the range periphery. The authors suggest this study may provide insight in how other river vertebrate populations may respond to planned dams and water developments.

Dr. Braulik added, "This important study shows that it is river by dams, and removal of river water for irrigation that has caused the massive range decline of the Indus River freshwater dolphin. This increased understanding of species decline in fragmented river systems is especially important because hundreds of new dams and water developments are planned or are under construction in many of the world's rivers and large losses of aquatic biodiversity can be expected."

Explore further: New river dolphin species found in Brazil (Update)

More information: Braulik GT, Arshad M, Noureen U, Northridge SP (2014) Habitat Fragmentation and Species Extirpation in Freshwater Ecosystems; Causes of Range Decline of the Indus River Dolphin (Platanista gangetica minor). PLoS ONE 9(7): e101657. DOI: 10.1371/journal.pone.0101657

add to favorites email to friend print save as pdf

Related Stories

Improved monitoring of endangered Ganges river dolphin

May 08, 2014

(Phys.org) —A new study reveals a method to improve the monitoring of the endangered Ganges river dolphin – one of only four remaining freshwater cetaceans since the Yangtze River dolphin became extinct ...

Bangladesh to set up dolphin sanctuaries

Oct 31, 2011

Bangladesh will declare three river areas in its southwest as dolphin sanctuaries, wildlife officials said Monday, in a bid to protect the country's population of endangered freshwater cetaceans.

Recommended for you

Genetically tracking farmed fish escaping into the wild

19 hours ago

European sea product consumption is on the rise. With overfishing being a threat to the natural balance of the ocean, the alternative is to turn to aquaculture, the industrial production of fish and seafood. ...

France fights back Asian hornet invader

22 hours ago

They slipped into southwest France 10 years ago in a pottery shipment from China and have since invaded more than half the country, which is fighting back with drones, poisoned rods and even chickens.

Tide turns for shark fin in China

22 hours ago

A sprawling market floor in Guangzhou was once a prime location for shark fin, one of China's most expensive delicacies. But now it lies deserted, thanks to a ban from official banquet tables and a celebrity-driven ...

Manatees could lose their endangered species status

Aug 19, 2014

About 2,500 manatees have perished in Florida over the last four years, heightening tension between conservationists and property owners as federal officials prepare to decide whether to down-list the creature to threatened ...

User comments : 0