By Akanshya Shah on MyRepublica.com
The growing trend of poison fishing in local streams and rivers across the country is threatening the aquatic life in four major river ecosystems -- Karnali, Koshi, Narayani and Mahakali. Rising use of a highly toxic pesticide called ´thiodan´ has specially threatened the already vulnerable dolphins.
At present, dolphin population in the four rivers is estimated to stand at only 130.
Of late, fishermen and companies granted fishing contracts by the Village Development Committees are using thiodan, an endosulfic organochloric toxin that hits the respiratory tracts of the pests and is thus regarded as very effective pesticide. Thiodan, which is banned in many countries across the globe, is popularly known as ´Machha Marne Ausadhi´ by many fishermen in Nepal, and is being extensively used in small streams that feed the small rivers like Mohana, Kandra and Pathriya in the rainy seasons and the big rivers in the dry season.
"In the last 7 or 8 years, many people are extensively using thiodan for fishing. This trend can have a long-lasting impact on the entire ecosystem," Manoj Gautam, coordinator of Roots & Shoots, Nepal, a local NGO working in the field of animal rights and rehabilitation, said.
One small can of thiodan (100 ml worth Rs 40) can destroy up to 7-15 km of an average sized stream like Mohana. The remain of the toxin can exis in the mud of the river-bed for decades as it does not disintegrate easily.
"This has remained unnoticed for years, but it is one of the biggest threats
to the dolphins of Nepal, especially in Karnali and its tributaries," Gautam
Gautam, who is presently conducting a research in the Mohana river dolphins, said the government must immediately check the use of thiodan to "protect the fishes," especially the dolphins," whose staples are now highly affected by the poison.
"During my research, I also found that the local Tharu community that relies on fishing for livelihood is not using thiodan in Kailali. It is the contractors who are resorting to this practice."
On the other hand, consuming fishes killed with thiodan can have severe impacts on humans as well. Thiodan is one of the Persistent Organic Pollutants (POPs). The molecules of POPs remain in human fat and have severe long-term health as well as genetic impacts on humans.
According to a latest local research carried out by Dolphin Conservation Center, Kailali, under the grant assistance by UNEP, the other major threats facing dolphin population is siltation and deposition in the river-bed due to heavy erosion in the Churia range.
"The shallowing of rivers creates risk of dolphins getting stranded in the bed due to the lack of enough water for them to float," Bhoj Raj Shrestha, the center´s director, said.
Shrestha, who has been involved in dolphin preservation for 20 years, added that the VDCs provide permits to fishermen from eastern Tarai to come to Kailali and use dangerous traps like monofilament gill nets that sweeps away all kinds of dolphin food species in Mohana River, a popular dolphin hangout during rainy season.
"Fishing in such a large and devastating scale should be banned and the DDC should stop providing fishing permits to such fishermen in these areas," Shrestha added.
The research has also pointed that old and new irrigation and hydropower dams are now coming in the hunting and breeding migratory routes of the species. A couple of new hydropower projects that Nepal is undertaking seem to have direct impacts on the survival of this species.
"Population fragmentation is another important issue that the dolphins face currently. They are seemingly forced to inbreed and thus getting genetically vulnerable," Gautam added.