The recent reports have brought some hope for marine life enthusiasts, revealing that Chinese pink dolphins, also known as Indo-Pacific humpback dolphins, are making a comeback in the Pearl River Estuary (PRE). These unique aquatic creatures are often referred to as Chinese white dolphins or pink dolphins, a nomenclature drawn from the color of their skin. This comeback is encouraging news given the substantial attention to the alarming decrease in various animal species worldwide.
The Pearl River Estuary
Encompassing major cities like Hong Kong, Macau, Shenzhen, Guangzhou, and Dongguan, the Pearl River Estuary is home to approximately 22 million people. Characterized by the Pearl River Delta, an area surrounding the PRE where the Pearl River merges with the South China Sea, it’s renowned as one of the world’s most densely urbanized locales. The region is heavily industrialized, and its waterway stands as one of the busiest shipping lanes globally.
Current Scenario and Contributing Factors
Dolphins rely on echolocation to navigate underwater. This sophisticated biological sonar used by dolphins, bats, and others, employ reflected sound to pinpoint objects’ locations, identifying threats, detecting prey, and avoiding obstacles, even in pitch darkness. However, this ingenious skill often gets disrupted due to heavy traffic of ships in the water, which also poses a direct threat to dolphin lives.
Recent observations have shown a rebound in dolphin numbers between Hong Kong and Macau owing to reduced ferry traffic amid the Covid-19 pandemic. Scientists claim that there has been a roughly one-third increase in pink dolphin sightings in these waters.
About the Indo-Pacific Humpback Dolphin
Scientifically named Sousa Chinensis, the Indo-Pacific Humpback Dolphin finds its habitat predominantly in the coastal waters stretching from central China through Southeast Asia to the Bay of Bengal. These dolphins are typically found in high densities in and around estuaries. However, their distribution appears fragmented, either due to natural reasons or human-induced activities.
According to the World Wildlife Fund for Nature (WWF), the PRE houses an estimated 2,500 dolphins of this species. However, a falling trend in juvenile numbers could potentially push down this figure.
These dolphins have suffered a steep decline, almost 70-80 percent, over the past fifteen years.
The Threats that Loom
The threats these dolphins face include both direct and indirect human activities such as agricultural and urban pollution, overfishing, and marine construction. Land creation for airport expansion, residential and office development, and transportation like fast ferries also pose significant risks. Some dolphins are even captured for entertainment purposes at marine parks and aquariums.
Such activities lead to habitat loss, dolphin mortality through entanglements and vessel strikes, and health issues due to exposure to chemical, sewage, and noise pollution.
Conservation Measures
Categorized as ‘Vulnerable’ by the International Union for Conservation of Nature (IUCN), active measures are required to conserve the Indo-Pacific Humpback Dolphin. The recent observation of their increasing number is a positive sign, but continued efforts are necessary to ensure their survival and prosperity.