Hong Kong’s pink dolphins

Their population has fallen by 70-80 percent in the past 15 years in what is one of the world's most industrialized estuaries.

Rare pink dolphins are returning to the waters between Hong Kong and Macau after the coronavirus pandemic halted ferries, but scientists remain deeply concerned about their long-term survival in one of the world’s busiest sea lanes.

Their population has fallen by 70-80 percent in the past 15 years in what is one of the world’s most industrialised estuaries. But this year their numbers have bounced back — and they have the pandemic to thank.

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Pink dolphins have been an important part of Hong Kong’s tourism and maritime history. The unique species was first spotted and documented in English by British traveler and writer Peter Mundy in Hong Kong near the Pearl River in 1637. Since then, their population has been getting significantly smaller and they are facing extinction soon if we don’t do our part to help.

Why are they pink

According to WWF pink dolphins – more suitably known as Chinese white dolphins – are white and become pink when they exert energy, somewhat like us when we exercise. The dolphins appear pink due to the ventilation (passing of blood and oxygen) underneath the skin – and even more so when they are swimming and jumping near the surface of the water.

Declining population

Only an estimated 2,000 pink dolphins are left in the Pearl River Delta – the minimum number that conservationists believe is needed to sustain the species’ population.

According to estimates made by dolphin researchers, if the pink dolphin population decreases by 2.5 per cent annually, the population number will be reduced by 74 per cent over three generations (spanning around 60 years). At a meager 47 pink dolphins left, the future for this species does not look good — especially if effective conservation measures are not introduced.

Plastic a major threat

One of the biggest culprits causing their decline in numbers is the amount of waste being dumped into Hong Kong’s seas. According to the Environmental Protection Department’s statistics, 16.5 tonnes of waste were poured into the sea last year.

Around 50 per cent of it was plastic (bottles, fragments, food wrappers, cutlery), while some 20 per cent was Styrofoam. Many of the ships passing through the waters are guilty of overfishing and causing underwater noise pollution, creating fewer areas that are suitable for breeding.

How are they still surviving

These worrying statistics raises the question: how are pink dolphins still surviving? There have been many studies on the different types of pollutants in our waters, but even today we don’t know the tolerance levels of pink dolphins. Needless to say, pink dolphins have been living in an unhealthy environment.

According to Hong Kong Dolphin Conservation Society there is a high level of waste and metals in their bodies, and these toxins are passed from mothers to their babies, causing a further threat to the pink dolphin population.

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