Background
The Yangtze River dolphins, also known as the Baiji, have long been an important part of the Yangtze’s ecology. Classified as a species of dolphin in the family Lipotidae, the Baiji inhabited the waters of the Chang Jiang (Yangtze River) in China since the Pleistocene era – 80 000 years ago. The Yangtze River dolphin is the first species of large aquatic mammal in human history to become extinct due to human-induced activities. Though a small population may still exist in remote areas in the river, it is thought that the species of Yangtze River dolphin has become extinct in the wild.
Habitat
The Yangtze River dolphins were adapted to live in the water of the Yangtze River. They could be found from the estuaries of major rivers and tributaries to the main river. The dolphins typically occurrence depths ranged from 0.5 to 10 meters depending on their activities. The surface water temperature of the Yangtze was usually between 9 – 25 degrees Celsius. The Yangtze River dolphins were found in the southwestern regions of China from the provinces of Hubei and Sichuan to the east of the outflow of the River Jialing and the Yalong river, being a large area of the River. The Dolphins preferred a turbid environment with a silt concentration of more than 8 milligramme per litre.
Natural Habitat Features
The Yangtze River dolphins lived in the main stream and its lower tributaries. The waterways of the river have some specific natural features, such as complex water flow, a high flow velocity, low surface salinity and the presence of sand or mud sediments. These natural features all positively influenced the dolphins’ inhabitation, reproduction, and growth. The Yangtze River dolphin’s main habitat had many features that are specific to the region and seemed to complement their behaviour. For instance, the river waters tend to be low in surface salinity and high in oxygen concentrations, as well as being slightly acidic and clear – factors which all had a positive influence on their ability to survive.
Generation of Controversies
The decline of the Yangtze River dolphins has generated debates amongst conservationists, ecologists and those involved in the fishing industry. Scientists argue that the main reason for this decline is the heavy human interference in the river by certain activities like water pollution, overfishing and degradation of the natural environment. Nonetheless, some fishermen have opposed the idea of completely protecting the dolphins as they believe that would bring a huge economic loss as they wouldn’t be able to fish in the river.
Protection Efforts
In an attempt to protect the Yangtze River dolphins, the Chinese government has implemented some protective measures, such as creating wildlife reserves, controlling and limiting fishing activities, reducing ocean exploration activities, enforcing restrictive laws and protecting areas where the Yangtze River dolphins live. In addition, the government has been investing in research and conservation efforts. They have worked on restoring habitats by taking measures like reclaiming land, conserving and improving water quality and providing food resources for the dolphins.
Decline
Despite all these efforts, the Yangtze River dolphins’ population was still declining in the 1990s due to the heavy human interference in the river. The main threats to the dolphins’ survival are industrial and agricultural pollution, overfishing, and habitat destruction. The Yangtze River dolphin population fell drastically, from an estimated 3800 in 1996 to just 13 in 2006. In 2006, it was declared that the species had become functionally extinct.
Impact of Human Intervention
The decline of the Yangtze River dolphins was directly caused by human activities in the affected areas. The main human activities in this region which affected the dolphins included: industrial and agricultural activities, overfishing, and the direct destruction of the natural environment. For instance, the discharge of industrial wastewater into the river damaged the aquatic environment and caused long term ecological damage. The release of fertilizers and pesticides introduced by agricultural activities have caused water pollution, which led to a substantial decline in the aquatic vegetation as well as significantly reducing the biodiversity of the river.
Overfishing
Overfishing, which involves the indiscriminate catching of fish, has been a major factor contributing to the decline of the river dolphins. Unsustainable and irresponsible fishing practices have disrupted the food chain of the Yangtze River, as well as reducing the food resources available to the dolphins. In addition, fishing boats have also had a negative effect on the environment as they work to trawl, resulting in the destruction of the dolphins’ natural habitat.
Habitat Destruction
Habitat destruction is another major factor that has contributed to the decline of the Yangtze River dolphins. Deforestation, water pollution and water diversion from the upper reaches of the river have resulted in changes to the river habitat of the dolphins. The building of the Three Gorges Dam on the Yangtze River has also caused changes to the environment of the river, including changes in water flow and temperature as well as an increased siltation of the river, all of which can have a negative effect on the dolphins’ habitat.
Pollution
Pollution is another issue that has had a major effect on the population of the Yangtze River dolphins. The river has been polluted by industrial and agricultural activities, as well as domestic and commercial waste. This has caused the water of the Yangtze to be polluted with various pollutants, including heavy metals, organochlorine contaminants, and chemical fertilizers. These pollutants have been found to be toxic to the Yangtze River dolphins, which has contributed to the decline of their population.
Dam Construction
The construction of the Three Gorges Dam has been a major cause of the decline of the Yangtze River dolphins. The dam has had a number of impacts on the river, including changes in water flow, temperature and siltation, all of which can have a negative effect on the dolphins’ habitat. In addition, the dam has also meant that the dolphins have lost access to areas of the river that were once prime habitats for them.
Final Thoughts
There is no doubt that the Yangtze River dolphins’ habitat has been severely impacted and disturbed by human activities. The decline of the population is thought to be directly caused by human activities in the affected areas, such as water pollution, overfishing and habitat destruction. Despite the various conservation efforts that have been taken, it seems that the Yangtze River dolphin population is in a continuing decline and is on the brink of extinction. It is therefore essential that more action is taken to protect the environment of the Yangtze River, in order to ensure the survival of this species.
