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.

The question asks for reasons *other than* poaching for the decline in the population of Ganges River Dolphins. 1. Statement 1 is correct. The construction of dams and barrages fragments the river habitat, isolating dolphin populations and restricting their movement, which affects feeding and breeding patterns. This is a major threat. 2. Statement 2 is generally considered incorrect as a primary driver. While crocodiles and dolphins coexist, an increase in the population of crocodiles is not widely cited as a significant factor causing the decline of Ganges River Dolphins. 3. Statement 3 is correct. Getting trapped accidentally in fishing nets (bycatch) is a major cause of mortality for these dolphins, as they are air-breathing mammals and drown if entangled. 4. Statement 4 is correct. Pollution from the runoff of synthetic fertilizers and other agricultural chemicals from nearby crop-fields degrades water quality. This affects the dolphins directly through toxicity and indirectly by contaminating their prey base and degrading their habitat. Therefore, the possible reasons, other than poaching, are 1, 3, and 4.