Dolphins dwindling for water pollution, illegal netting

Sadiqur Rahman | Published: 02:02, Nov 09,2018

 
 

A dolphin, a rare sight nowadays in the rivers of the country, appears where the River Kaliganga meets the River Dhaleshawari at Hazratpur under Keraniganj in Dhaka. — Sony Ramany

Growing commercial activities, water pollution, increase in salinity in the coastal areas and illegal netting are contributing to decrease in dolphin population in the country.
Quoting an ongoing census on dolphin in the Sunderbans and other coastal zones, experts have told New Age that the number of the mammals is dropping.
The census under a project ‘Expanding the Protected Area System to Incorporate Important Aquatic Ecosystem’, scheduled to be completed in 2019, is jointly conducted by Department of Forest, International Union for Conservation of Forest with the support from the United Nations Development Programme.
The experts say that occurrence of the Gangetic dolphin, a freshwater species, already reduced due to rapid industrialisation along the inland river shores in Bangladesh.
Another iconic species Irrawaddy Dolphin, frequently found in the brackish water bodies in the south-western region of the country, are also under threat because of illegal netting and poising, they say.
The world’s largest mangrove forest the Sunderbans and its adjacent areas are one of the major sanctuaries of two globally-endangered river dolphins — Gangetic or Ganges River Dolphin and Irrawaddy Dolphin, an ongoing survey has found.
IUCN Bangladesh’s senior programme officer and researcher ABM Sarwar Alom said that at least half of the 7,000 global population of Irrawaddy dolphins were currently living in the country.
Dolphins are among the world’s most threatened mammals as per the IUCN red list.
Local conservationists have been urging the government to announce dolphin as a national aquatic animal citing the species’ iconic value.
In 2012, the government declared 10.7 square km area of the Rivers Pashur and the Andharmanik and their channels in Dhangmari, Chandpai and Dudhmukhi areas and the neighbouring the Sunderbans as dolphin sanctuaries.
Earlier in 2006, the first dolphin census in the Sunderbans was conducted by Wildlife Conservation Society.
The census report found 225 Gangetic dolphins, locally known as Sushuk, and 451 Irrawaddy Dolphins.
Of the 40 species of dolphins in the world, four are found in the Sunderbans area. Finless porpoise and the pink Indo-pacific humpback dolphins are occasionally seen here.
Jahangirnagar University’s zoology professor, also researcher of the ongoing census project, Monirul H Khan has told New Age that illegal netting during fishing in the inland and coastal rivers poses a threat to the dolphin population critically.
Monirul says, ‘Eighty per cent of the dolphins die due to illegal netting using monofilament fishing net. The rest are killed by poisoning and public lynching.’
He notes that dolphin, despite being an aquatic animal, needs to breath in the open air.
Although dolphins are not usually captured with intent, every year dozens of dolphins get entangled in fishing nets and die.
‘When they are caught in the net and forced to remain stuck a bit longer time in the water, the dolphins die because of suffocation,’ Monirul points out.
Dolphins often get entangled in bank-to-bank fishing nets or hunted in some areas for their assumed medicinal properties.
Apart from this, dolphins are facing habitat threats, particularly in the Sunderbans, due to poisoning and pollution by industrial effluents and operation of water transports.
Monirul recalls that occurrence of Gangetic dolphins were common even three decades ago in the River Buriganga in Dhaka.
Nowadays, freshwater dolphins have become rare and are occasionally spotted in some large rivers like the Padma, although, the experts say, the mammals could be sighted in all major rivers of the country just a few years ago.
According to Monirul, rise in salinity in the coastal rivers, poor flow of fresh water in the Ganges river system are also posing habitat threats to the iconic animal.
According to a Power Division meeting on September 12, 2017, 21 new coal-fired power plants, including controversial 1320MW Rampal Power Plant in close proximity of the Sunderbans were being implemented in Bangladesh. Thirteen of the plants would be installed in five coastal districts.
Monirul fears that access to power can attract more industries near the power plant areas creating huge chance of water pollution and habitat threats to aquatic lives.
IUCN officer Sarowar, however, thinks that dolphin conservation efforts are undergoing with the involvement of local people to curb illegal netting.
He says that as part of the ongoing census, the team so far has identified six hotspots and some semi-hotspots of the Gangetic and Irrawaddy dolphins.
The hotspots and semi-hotspots cover an area of around 982 square kilometres.
He said that a 10-day dolphin fair featuring puppet shows, bioscope, video documentary, folksong presentation and art competition for children was launched in the villages near the Sunderbans on Sunday to build awareness among the local community.

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