Wildlife experts in south China are trying to rescue an endangered Chinese white dolphin (Sousa chinensis) that is in worsening health after swimming into a tributary of the Pearl river a week ago. The dolphin is approximately 30 years old and swam into the Baisha Rivernear Jiangmen in Guangdong Province on the 1st of February. It is now in a stretch of water about 100 km from the sea. “[…] the skin of the dolphin is festering and its health is deteriorating … its moving area is shrinking,” said Feng Kangkang, a worker with Jiangmen Chinese White Dolphin Nature Reserve, on Thursday. The team is watching the dolphin around-the-clock and recording its health condition, according to the Guangdong provincial ocean and fishery department. Dubbed the “giant pandas of the sea” by some, the Chinese white dolphins are mainly scattered in a few coastal areas where they exist in small numbers. About 2,000 are known from areas around the Pearl River, including HK which at the last count, was down to about 60 dolphins. (Photo/Xinhua)
As reported by several news outlets this week, a Chinese White Dolphin (Sousa chinensis) – aluas Indopacific Humpback Dolphin or ‘pink dolphin’ – was spotted near Guangzhou in the Pearl River on Wednesday the 21st of October. This drew some crowds as the dolphin stayed for about an hour. Conservation staff later used sonar equipment to try to herd it back out towards the sea -apparently with some success.
This story is however quite hyped-up, because these dolphins live near estuaries and previous studies have shown they move further into the estuary in the dry winter months when less freshwater is flushed into the sea by the Pearl River. In summer when the heavy rains come and the river swells the dolphins range extends further out. This is likely because they are following fish stocks that themselves track a line of salinity which mobmves in and out of the estuary with the seasons. Some fish like the flathead mullet (Mugil cephalus) commonly sold in fish markets also move in and out of fresh and seawater depending on their stage in life.
Speaking of which, I saw another prize catch of a mullet on the central waterfront yesterday. It’s a bigger fish than I have seen in any market at about 40 cm and probably 2+ kg – it drew a small crowd and plenty of mobile phone cameras. congratulations to the lucky angler!
I have just added a page about all the different species of ray that are found in Hong Kong. Here is a little preview on just the stingrays. Check out the full list of rays here.
The Stingrays of Hong Kong:
Round ribbontail Ray / Black-spotted stingray (Taeniura meyeni)
A bottom-dwelling inhabitant of lagoons, estuaries, and reefs, generally at a depth of 20–60 m (66–197 ft). Reaching 1.8 m (5.9 ft) across. Generally nocturnal, the round ribbontail ray can be solitary or gregarious, and is an active predator of small, benthic molluscs, crustaceans, and bony fishes. Although not aggressive, if provoked the round ribbontail ray will defend itself with its venomous tail spine. In Hong Kong, it is found mainly in the relatively clear southern and eastern waters, but it has also been found in the northern part of Lantau and in brackish water near the Pearl River estuary. It is also one of the species that has been found on Hong Kong’s artificial reefs. Check out Eric Keung’s spooky photo of a this stingray in Hong Kong waters.
Between July 2005 and June 2008 there were two cases of people being stung by stingrays in HK – fortunately with mild outcomes. The sting and its venom can cause bluish or greyish discoloration around the wound, disproportionate pain, muscle cramp, weakness, seizure, hypotension, cardiovascular toxicity, deep wounds and lacerations. In other words, stingrays are dangerous! Just watch from a distance and don’t touch!
Blue-Spotted Stingray (Neotrygon kuhlii)
The body is rhomboidal and green with blue spots with a maximum width estimated at 46.5 centimeters (18.3 in). The rays coloration is a warning for the highly poisonous barbs, thus few animals attempt to overpower this ray. In HK, they are more easily seen in summer in the shallow water along the coast, on coral reefs and in mangrove areas. Because of the venomous sting observers should not get too close or try to touch it!
Pale-edged stingray (Dasyatis zugei)
A bottom-dwelling ray most commonly found over sandy areas shallower than 100 m (330 ft) and in estuaries. It measures up to 29 cm (11 in) across, has a diamond-shaped pectoral fin disc, a long projecting snout, small eyes, and a whip-like tail. It is chocolate-brown above and white below and feeds mainly on small crustaceans and fishes. In HK it is mainly found in the western Pearl River estuary south of Lantau Island.
A newborn dolphin, a small marine cousin of the dolphin, died at Ocean Park last night, where it had been born just 73 hours earlier. Its death came on the same day that two other finless porpoises were revealed to have been found dead on the city’s beaches.
The dead calf’s mother was said to have had a difficult labour, and her baby, a female, immediately displayed an abnormal swimming pattern. The theme park said she also found it difficult to stay alongside her mother when she was not suckling.
Necropsy results show the calf’s stomach was empty, and about 25 per cent of her lungs were not fully expanded. The theme park said it was not uncommon for dolphins to die in infancy, citing a previous study of dolphins in Western Australia, which showed 44 per cent of calves do not survive to three years of age.
Meanwhile, Mui Wo resident Leslie Parker said her son and his friend found the body of what was initially thought to be a seal or sea lion on the rocks near Lower Cheung Sha beach on Wednesday.
Officers from the Agriculture, Fisheries and Conservation Department and Ocean Park’s Cetacean Stranding Response Team visited the site yesterday evening to conduct an autopsy. They removed the carcass for further examination.
A dolphin, which lacks a dorsal fin, may appear similar to a sea lion, said Dr Samuel Hung Ka-yiu, chairman of the Dolphin Conservation Society. However, the porpoise has a smoother skin, with no hair, and it has a tail, while the sea lion has flippers. The species is considered vulnerable by the International Union for Conservation of Nature.
“The six months between December and May have always been the time of the year when most strandings of dolphins are reported,” said Hung, adding that gillnet fishing was usually the cause of dolphin deaths in Hong Kong waters.
Yesterday morning, police received another report of a dead finless porpoise – this time a 158cm-long adult, which was discovered at a beach off Tai Wan Tau Road, Tseung Kwan O.
The Ocean Park response team were again sent to the scene and took a sample to find out the cause of death. A spokeswoman described it as “severely decomposed”, with signs of having been strangled by a fishing net. There were also bruises on its tail.
There were 32 reports of finless porpoise strandings last year.
Reported by the SCMP ON 2nd April, 2015
Last weekend Simon Holliday, 35, set a record for the crossing of the Pearl River Delta in a time of 10 hours, 20 minutes, and 30 seconds, beating the time of Beijing swimmer Zhang Jian who swam across in 10 hours 30 minutes in 2005.
‘There were tough moments – lots of big tankers in the start, and lots of time to contemplate what I was doing, but the jellyfish didn’t appear, and instead, the dolphins did, for over an hour!’ Holliday was accompanied by a pod of pink dolphins, obviously keen to support another ‘pink’ thing swimming in the murky waters of the Pearl River Delta. Pink dolphins are a massively endangered species, mostly on account of habitat degradation and destruction. ‘It was one of the most amazing moments of my life to see them around us for so long, even though I had to keep my head down and kept going.’
Doug Woodring of the Ocean Recovery Alliance said: ‘I’ve never seen so many dolphins – at one point there was around 30 of them. Today was not just a great day for the ocean, but a great day for Hong Kong open-water swimming.’
Holliday began his swim at 5am from Peaked Hill (Kai Yet Kok), on the west edge of Lantau Island, Hong Kong and swam approximately 35km to Hac Sa Beach in Macau, arriving at [3:40pm]. The swim has raised over $250,000 HKD for Ocean Recovery Alliance and their project Grate Art, which brings together eight local and Chinese artists to create plaques used to remind people not to dump into drains on the street, as these sometimes flow into the ocean.
Asked the first thing he was going to do after emerging from the water, Holliday remarked: ‘I am going to have a pint of beer, in a glass.’
Simon Holliday is an open-water swimmer based in Hong Kong. Simon swam across the English Channel in August 2011 and has done several long swims around the UK and Ireland.
Ocean Recovery Alliance brings together new ways of thinking, technologies, creativity and collaborations in order to introduce innovative projects and initiatives that help to improve our ocean environment. It has two projects with the Clinton Global Initiative focused on the reduction of plastic pollution, and is one of the only NGOs in the world to be working with both the United Nations Environment Programme (UNEP) and the World Bank’s Global Partnership for Oceans. It also organises Kids Ocean Day in Hong Kong, Hong Kong-San Francisco International Ocean Film Festival (May 6-11, 2014), and the international business forum, Plasticity, on the future of plastic, where is can be used, without the ‘footprint.’
Source: Ocean Recovery Alliance