Prelims 2014 · archive
MediumOther than poaching, what are the possible reasons for the decline in the population of Ganges River Dolphins?
- 1.Construction of dams and barrages on rivers
- 2.Increase in the population of crocodiles in rivers
- 3.Getting trapped in fishing nets accidentally
- 4.Use of synthetic fertilizers and other agricultural chemicals in crop-fields in the vicinity of rivers
Select the correct answer using the code given below.
Answer & explanation
Answer: (c) 1, 3 and 4 only
Ganges River Dolphins are mainly threatened by loss and fragmentation of river habitat, accidental entanglement in fishing nets, and polluted water. Dams and barrages, accidental netting and chemical runoff from farmland therefore fit. A rise in crocodile numbers is not a recognised threat.
- ✓ 1. Dams and barrages block the dolphins' movement and fragment their habitat. The north-westernmost reaches of the dolphin's range have seen significant declines because of dams and barrages built over the last six decades.
- ✗ 2. Crocodile numbers are not listed among the threats to this dolphin. The major threats are habitat fragmentation, fishery interactions and water pollution.
- ✓ 3. Dolphins get accidentally entangled in gillnets and drown. This bycatch is a major threat, separate from deliberate hunting.
- ✓ 4. Water pollution is a major threat. Dolphin blubber shows significant buildup of heavy metals and of organochlorine and organophosphate residues, which come from pesticides and similar agricultural and industrial chemicals. Farm-chemical runoff from fields near rivers adds to this pollution.
- ✓ (c) Only statements 1, 3 and 4 describe real threats, so the code '1, 3 and 4 only' is right.
- ✗ (d) This option adds statement 2, the crocodile statement, which is not a recognised cause of decline.
Remember · Ganges River Dolphin threats: dams and barrages (habitat fragmentation), accidental entanglement in gillnets, and water pollution including agrochemicals. Hunting and poaching for oil and flesh is the other major cause.
Sources
- UNEP/CMS Concerted Action 13.6 (Convention on Migratory Species) – Ganges River Dolphin: habitat fragmentation by dams and barrages ↗ “The north-westernmost reaches of the Ganges River Dolphin’s distribution range have seen significant declines due to construction of dams and barrages over the last six decades … local impacts on populations from fishery interactions (bycatch in entangling gillnets, hunting and poaching for oil and flesh), and water pollution are major threats … Studies have shown significant bioaccumulation of heavy metals, organochlorine and organophosphate residues, and other contaminants in dolphin blubber”
Question: UPSC Civil Services (Preliminary) 2014, General Studies paper. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·