UPSC Prelims 2014 Q14: Environment & Ecology – Biodiversity & Conservation
Other 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.
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1, 3 and 4 only
- (d) 1, 2, 3 and 4
Answer: (c) 1, 3 and 4 only
Explanation
Decline of the Ganges River Dolphin
| Reason | A cause of decline? | Fact |
|---|---|---|
| 1. Construction of dams and barrages on rivers | Yes | They split dolphin populations and reduce flow |
| 2. Increase in the population of crocodiles in rivers | No | Crocodiles are not a reason for the decline |
| 3. Getting trapped in fishing nets accidentally | Yes | Bycatch in gill nets drowns dolphins |
| 4. Use of synthetic fertilizers and other agricultural chemicals near rivers | Yes | Run-off pollutes the water and their prey |
About the dolphin:
| Feature | Detail |
|---|---|
| Status | Endangered; Schedule I |
| Title | National Aquatic Animal |
| Sense | Nearly blind; uses echolocation |
| Sanctuary | Vikramshila, Bihar |
Answer: (c) 1, 3 and 4 only.
Why each option is right or wrong
- (a) Incorrect. Crocodiles are not a cause, and fishing nets and chemicals are left out.
- (b) Incorrect. An increase in crocodiles is not a reason for the decline.
- (c) CORRECT. Dams, fishing nets and agricultural chemicals threaten the dolphins.
- (d) Incorrect. Statement 2 on crocodiles is false.
Key point
Ganges river dolphin threats: dams and barrages, bycatch in fishing nets, pollution from farm chemicals, poaching for oil. Not crocodiles.
Remember
Dolphin decline: dams, nets, chemicals.
Common mistakes
- Including crocodiles, which are themselves declining.
- Forgetting that barrages such as Farakka divide dolphin populations.
- Overlooking farm run-off as river pollution.
Exam tip
Threats to river animals are almost always human-made: dams, nets, pollution.
Sources
- Ministry of Environment, Forest and Climate Change — Conservation Action Plan for the Gangetic Dolphin 2010-2020
- IUCN Red List — Platanista gangetica