Help Out the Horseshoe Crabs At Shui Hau Wan, Lantau

You may have heard of Shui Hau Wan on Lantau Island, which is a popular location for clam digging and kite boarding. Shui Hau is actually an important wildlife habitat housing a wide range of precious species, including the horseshoe crab.
Horseshoe crabs are marine living fossils, probably dated back to 485 million years ago. There are two horseshoe crab species found in Hong Kong – Chinese horseshoe crab (Tachypleus tridentatus) and mangrove horseshoe crab (Carcinoscorpius rotundicauda). For more info on HK’s horseshoe crabs visit Billy Kwan’s webpage Horseshoe Crab in Hong Kong.

Trash from visitors as well as marine debris are major threats to the juvenile horseshoe crabs living in the mudflat. To learn more about the features of the ‘living fossil’ horseshoe crab, their importance to humans and how their habitat is being affected by human activities, you can join the mudflat cleanup organized by Friends of the Ocean Park Conservation Fund. Details in the graphic below.

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For enquiries, please contact Miss Chan at +852 3923 2217.

Turtles Returned to the Sea

The Agriculture, Fisheries and Conservation Department (AFCD) released three green turtles, comprising two juveniles and an adult, and a juvenile hawksbill turtle in the southeastern waters of Hong Kong yesterday (June 23 2014).

The juvenile green turtles and juvenile hawksbill turtle were found by members of the public and staff members of the AFCD on Clear Water Bay Second Beach and Campers’ Beach in Sai Kung and Yan Chau Tong between October 2012 and May this year.

After an initial check-up by the AFCD, the turtles were taken to Ocean Park (OPHK) for a thorough veterinary assessment. Since then, they have been looked after at OPHK with constant monitoring and veterinary care.

The adult green turtle had been kept by OPHK since 2002. It was among the hatchlings artificially incubated from a batch of eggs collected in Sham Wan on Lamma Island in 2001. Due to a slight deformity found in its shell, it had been looked after by OPHK since then.

Current weights of the juvenile turtles ranged from 4.05 to 12.85 kg and their shells were from 35 to 47cm in length, while the adult turtle weighed 76.5 kg and its shell was 79cm. All of them were in good condition, indicating that they were ready to be returned to the sea. The AFCD is thankful to the public for their immediate reports, and the veterinarians and aquarium staff of OPHK for their efforts in taking care of these sea turtles.

Before returning them to the sea, the AFCD tagged each turtle with a microchip and Inconel tags for future identification, and attached a satellite transmitter to its back. By tracing their oceanic movements and locating their feeding grounds, the AFCD can collect data for formulating appropriate conservation measures and share findings with various conservation authorities. This will be conducive to the effective protection of the species among nations.

The green turtle and hawksbill turtle are globally endangered and critically endangered species respectively. Members of the public are urged to report any sighting of sea turtles to the department via 1823 to help protect them. The AFCD will continue its efforts in sea turtle conservation through monitoring, habitat management and educational activities.

In Hong Kong, all sea turtle species are protected under the Wild Animals Protection Ordinance (Cap 170) and the Protection of Endangered Species of Animals and Plants Ordinance (Cap 586). Of the five sea turtle species found in Hong Kong waters, the hawksbill turtle is relatively rare and the green turtle is to date the only species known to nest locally.

Turtles Returned to the Sea

The Agriculture, Fisheries and Conservation Department (AFCD) has released three green sea turtles (Chelonia mydas), including 2 juveniles and 1 adult, and 1 juvenile hawksbill turtle (Eretmochelys imbricata) in the southeastern waters of Hong Kong today.

The juvenile green turtles and the hawksbill turtle were found by members of the public and AFCD staff on Clear Water Bay Second Beach and Campers’ Beach in Sai Kung and Yan Chau Tong between October 2012 and May this year.

After an initial check-up by the AFCD, the turtles were taken to Ocean Park for a veterinary assessment and care.

The adult green turtle, which has been taken care by Ocean Park since 2002, returns to the sea. (Image by AFCD)
The adult green turtle, which has been taken care by Ocean Park since 2002, returns to the sea. (Image by AFCD)

The adult green turtle was kept by Ocean Park since 2002. It was among the hatchlings artificially incubated from a batch of eggs collected in Sham Wan on Lamma Island in 2001. Because it had a slight deformity on its shell, it was looked after by Ocean Park.

The juvenile turtles ranged from 4.05 to 12.85 kg in weight and their shells were from 35 to 47cm in length, while the adult turtle weighed 76.5 kg and its shell was 79cm. All of them were in good condition, indicating that they were ready to be returned to the sea.

Before returning them to the sea, the AFCD tagged each turtle with a microchip and Inconel tags for future identification, and attached a satellite transmitter to their backs. By tracing their oceanic movements and locating their feeding grounds, the AFCD can collect data for formulating appropriate conservation measures and share findings with various conservation authorities such as tha Gangkou Sea Turtle National Nature Reserve in Huidong (Guandong Province).

The Agriculture, Fisheries and Conservation Department released green turtles and hawksbill turtle in the southeastern waters of Hong Kong today (June 23). Before the turtles are released back into the wild, satellite transmitters are attached to their back to collect information on their movements. (Image by AFCD)
The Agriculture, Fisheries and Conservation Department released green turtles and hawksbill turtle in the southeastern waters of Hong Kong today (June 23). Before the turtles are released back into the wild, satellite transmitters are attached to their back to collect information on their movements. (Image by AFCD)

Of the five sea turtle species found in Hong Kong waters, the hawksbill turtle is relatively rare and the green turtle is to date the only species known to nest locally.

 

Lion’s manes, invisible barnacles, suicidal fish, and photoshop hoaxes

It’s definitely summer and the sea has seasons, too. With summer comes the dread of Hong Kong’s beach-goers, the season of the lion’s mane jellyfish Cyanea nozakii.
This large, flat-topped jellyfish can grow to 50 cm in width with 8 bunches of 70 to 120 stinging tentacles that can trail up to 10 m. These tentacles can still sting even when they break off or are torn from the main body (though they lose potency over time).
It is cream to pale yellow with a darker centre and transparent on the outside edge.

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A lion’s mane jellyfish (Cyanea nozakii) drifts close to the surface off Lantau Island.

You start to see these guys arrive from late March onwards and they reach their peak in mid-summer and decline in numbers after that.

Although it occurs all over the Indo-Pacific, seasonal outbreaks of the lion’s mane occur in the Yellow and East China seas and the Gulf of Bohai where fisherman regard them as a nuisance : first because they clog up nets and even damage them, second because their presence is linked to the decline of the edible jellyfish Rhopilema esculentum. Although it used to appear sporadically in those areas, it seems to have become more and more of a problem. One Chinese researcher even said that more harm and damage was caused to the coastal waters of China by this species than by red tides. Personally I have not noticed any change in Hong Kong over the years, but maybe I am wrong. When I was a kid (in the 80’s) I remember trying to count the number of jellyfish we passed off Lamma Island in our boat and lost count after 100 in 5 minutes…on average adults weigh about 1.2-1.3 kg so we passed literally a tonne of jellyfish in 5 minutes (and it was a slow boat).
So what about the barnacle and the suicidal fish?
Well, remember symbiosis from high school biology? The jellyfish are sometimes accompanies by other creatures taking advantage of the bad-ass protection offered by the stinging tentacles. One interesting guy is a transparent, soft barnacle called Alepas pacifica that hitches a ride by attaching itself to the outer rim of the jelly’s bell with a stalk and spends the rest of its life in care free existence filter feeding particles out of the water – not a care in the world. Until the jellyfish dies, then it will, too.

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Three Jellyfish Barnacles (Alepas pacifica) attached to a jellyfish.

And the other two creatures are two commercial fish: the Razorbelly Scad (Alepes kleinii) and the Malabar Trevally (Caranx malabaricus). Both fish as juveniles like to seek out a lion’s mane soon after they hatch from eggs which – with perfect timing – seems to coincide with the arrival of the jellyfish. Hanging around the jellyfish gives them protection from predators. Think this is perfect adaptation? You would be wrong. The fish might gain an advantage from hiding by the jellyfish but they have not evolved any mechanism to avoid or deal with the stinging tentacles! Think of a child hiding from the bogeyman on top of a high voltage electricity pylon and you get a good idea of the risk to the fish. They have to swim very, very carefully! And on top of all that they are very loyal or attached to this dangerous fortress, too. When a jellyfish are caught and handled the fish stay with the jellyfish until inevitably they are forced into contact with the tentacles and are repeatedly stung until the die. Suicidal fish.

You can find more information on Hong Kong marine symbiosis in the book “Partnerships in the Sea: Hong Kong’s Marine Symbiosis” by Brian Morton.

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An adult razorbelly scad (Alepes kleinii).
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An adult Malabar Trevally (Caranx malabaricus). As juveniles they use the lion’s mane for protection from predators.

And now – sex:

Jellyfish can reproduce sexually and asexually. And when they chose sex it’s between male and female jellyfish – not that you can tell the difference unless you have a microscope and a lot of time. But like most invertebrates they simply try to time their spontaneous ejection of sperm and eggs into the water and hope that some meet, fertilise and grow into larvae. The microscopic larvae, called planula, are tiny, hairy, slipper-shaped things that use their tiny hairs (called cilia) to propel themselves. The planula larvae  of the lion’s mane only last a day and a half before they settle on the seabed and turn into small polyps like coral except solitary instead of in big colonies. After that they bud off little 2-3 mm wide jellyfish which then grow into the adult 20-30 cm wide jellyfish we all fear coming into contact with while swimming.

The life cycle of a jellyfish. Staring from planula larvae (1) to adult medusa (14). (From Schleiden M. J. "Die Entwicklung der Meduse". In: "Das Meer", A. Sacco Nachf., Berlin, 1869.)
The life cycle of a jellyfish. Staring from planula larvae (1) to adult medusa (14). (From Schleiden M. J. “Die Entwicklung der Meduse”. In: “Das Meer”, A. Sacco Nachf., Berlin, 1869.)

Photoshop hoax:

Some time ago the below image circulated online of a gigantic lions mane jellyfish dwarfing a diver.  This is actually a different species (Cyanea capillata) to our lions mane (Cyanea nozakii) even though it shares the same common name. Thanks to Google’s reverse image search the image was quickly exposed as a photoshopped fake as you can read in this Forbes article .

Photoshoped image of a lions mane jellyfish with a diver. L=Impressive sight, sadly a fake.
Photoshoped image of a lion’s mane jellyfish with a diver. L=Impressive sight, sadly a fake.
And finally some interesting recent research on the lion’s mane jellyfish:

– Researchers in Qingdao investigating the venom of the stinging tentacles found it was most stable for storage at -80 degrees Celsius and that it was more effective at killing human colon cancer cells compared with human liver cancer cells.

– Researchers in Lianyungang attempting to find some sort of use for the enormous unwanted by catch of lions manes in fisheries found that it is a good source of collagen and that compared to other sources of collagen it had lower levels of arsenic, mercury and lead.

– Researchers in Japan have tried to isolate the gene responsible for the lions manes production of an enzyme called endoglycoceramidase which is useful in synthesising some other molecules. Also in Japan researchers worked on the acoustic signature of different jellyfish species to develop an avoidance system for fishing boats. The acoustic signature is essentially the characteristics of the echo received from a pinger when the sound waves hit the jellyfish. Unfortunately they were not able to tell jellyfish species apart , which would have been a wonderful way to quickly measure their populations by just towing a pinger over a vast area and then estimating the population from the echo data.

HK Airport 3rd Runway Risks Loss of Hong Kong’s Remaining Dolphin Population

Conservationists claim that only three sightings of Chinese white dolphins have been recorded in Hong Kong this year.
The population of Hong Kong’s Chinese White Dolphins has dropped by 60% since 1997 in what the Hong Kong Dolphin Conservation Society (HKDCS) calles an ecological disaster. Since 1997 the dolphin’s habitat saw the completion of the Chek Lap Kok International Airport, wave after wave of town development in Tung Chung and Tuen Mun, a landfill development and more recently, the construction of the Hong Kong-Zhuhai-Macau Bridge project which is still ongoing. This HKDCS says has almost destroyed the white dolphins habitat.

According to statistics, there were 158 white dolphins in Hong Kong in 2003 but this number fell to 62 last year (2013) – a drop of 60% -causing great concern. In addition the current scheme to build a third runway at the airport, would cover an area of 650 hectares and would be the second largest reclamation project ever and is loacted in the white dolphins habitat. But the Airport Authority so far refuses to set meet with environmental groups and refuses to give full explanation of data and has been jointly criticized by nine environmental groups. It is currently understood that the Airport Authority will soon publish and interim Environmental Impact Assessment report on the third runway project and a 30th public consultation will be held.

WWF Infographic showing threats to the chinese white dolphin in Hong Kong (click to enlarge to original size)
WWF Infographic showing threats to the chinese white dolphin in Hong Kong (click to enlarge to original size)

The construction works have forced the dolphins to move further west as the noise affects their navigation and communication skills and the barges parked in the harbor creates sediment blooms affecting their food supply. Either that or they’ve died and or giving less birth.

Samuel Hung, President of Hong Kong Dolphin Conservation Society, urged the public to make good use of 30th consultation to express their views and take concrete actions to protect white dolphins. The Hong Kong dolphin conservation, Hong Kong Friends of the Earth and public Professional Union has conducted a “social cost and the returns assessment” study to estimate the effects of the third runway project’s on the public and its social effects which found that the white dolphin could earn Hong Kong some HKD 36.1 billion over ten years in ecological tourism revenue.

Huge, Critically Endangered Chinese Bahaba given as Father’s Day Present

A man has spared no expense on a ¥3million (£285,500) fish for his father-in-law.

The 50kg Chinese Bahaba (Bahaba taipingensis, Giant Croaker or黃唇魚 or 黄唇鱼) is 1.6m long and was caught as part of a local Dragon Boat Festival tradition in Fujian Province.

‘We’ve never seen such a big Bahaba in many years,’ said locals.

The fish is found on the coast of China, from the Yangtze River estuary southwards to the Pearl River estuary, including the waters of Hong Kong and Macau. It is a marine species that reaches lengths up to 2 metres (6 ft 7 in) and weights in excess of 100 kilograms (220 lb). Its natural habitats are shallow seas, subtidal aquatic beds, rocky shores, and estuarine waters. It enters estuaries to spawn and may be present there seasonally in large numbers. These include the Yangtze River, the Min River and the Pearl River and around the coast of Zhoushan Island (off the coast of Ningbo). It feeds mostly on shrimps and crabs.

It spawns in April and after spawning, the adults move out to deeper waters. Juveniles may be found in estuarine and coastal areas.

It is threatened by massive over fishing that continues despite legal protection in mainland China. Annual catches of fifty tonnes were taken in the 1930s but this had dwindled to 10 tonnes per year by the 1950s and 1960s by which time few large fish were caught. Despite legal protection in the mainland China, it is has no legal protection in Hong Kong, but it has been listed as critically endangered by the International Union for Conservation of Nature.  It is still caught and landed in mainland China, because of the immense monetary value placed on the swim bladders of this fish for use in traditional Chinese medicine. The swimbladders (maw) price depends on its age and shape, sex and size of fish, and even on the place and season of capture. In some markets, notably the Chinese markets, a good specimen swim bladder fetches more than its weight in gold.

Help urge more protection for this species by signing this petition online: “It is high time to protect the Chinese Bahaba”

Spawning populations are no longer known (fishing was targeted on spawning aggregations in estuaries in the past) and, given the heavy fishing pressure in the region, there are likely to be few or no refuges remaining for recovery. In addition, the estuaries in which this species spawns are degraded which may also have affected populations. It is not clear whether spawning aggregations of the species still occur, although some evidence suggests they might close to Xiqiyang, Dongguan, Pearl River. Dongguan by the way is one of Southern China’s biggest manufacturing cities.  Bahabas are vulnerable because of their biological characteristics of large size, restricted geographic range and aggregating behaviour in and around estuaries. When aggregating in estuaries they often produce sounds that makes individuals particularly easy to find.

By the 1990s, only small fish (<30 kg) were taken in Hong Kong waters sporadically, and large individuals (>50 kg) had become rare. Greatest catches were taken in the weeks prior to full and new moons with up to 300 fish taken in a season in Hong Kong in the past; now only the occasional small fish is taken. The last large Bahaba seen in Hong Kong was caught in 2008…

Source of the Father’s Day news item : Metro, 9/6/2014

Further Reading:
2001 article on the biology of the Chinese Bahaba from the “Porcupine” Newsletter of HKU’s Department of Ecology & Biodiversity

2010 blog post from Alex Hofford Photography on Bahaba products for sale in Sheung Wan

2012 Business Insider article of recent Bahaba catches and market prices

Hong Kong Federation of Women webpage detailing how expectant and new mothers can obtain fictitious health benefits by contributing directly to the extinction of the Chinese Bahaba
(FYI only, please don’t buy any Bahaba or Bahaba products!)

SCMP news item from 2008

Petition to for more protection of the Bahaba

Call for Protection of South Lamma Waters for Turtles

The following item was taken from the SCMP of the 7/6/2014. I should mention before you read it, that the AFCD is supposed to close Sham Wan and clean up the beach for nesting season from 1st of June each year, but a personal acquaintance of mine confirmed that by 8th of June this year nothing had been done and Sham Wan was covered in rubbish and the bay was full of pleasure craft and water skiers….either the rules changed or AFCD is not doing its job.

“Give Hong Kong’s green turtles a fighting chance to survive”

Five species of sea turtle can be found in Hong Kong. One of them, the green turtle, actually nests here. This giant used to nest on the beaches of several offshore islands, and the eggs were harvested and sold by local villagers. Now, only Sham Wan on Lamma Island supports a very small breeding population.

A decline in sea turtle populations has been observed in many locations across Asia. One increasingly significant cause is the exploitation of turtles for trade in their products or even in whole specimens.

A report by Traffic, the wildlife trade monitoring network, indicates that there has been an increase in demand for sea turtle products in China. There have also been strong indications that some fishing vessels from China are targeting sea turtles in their operations in tropical Asia. This is reflected by a growing number of cases of Chinese fishing vessels being detained by Southeast Asian countries and protected sea turtles being found on board.

Green turtles are slow to mature: it takes between 26 and 40 years before they are able to breed. Once they reach adulthood, they have few natural enemies and can live and reproduce for a long time.

The most vulnerable stages of their lives come when they are in the egg and when they are small hatchlings. It is estimated that only two to three turtles in every thousand survive to return to their natal beaches to breed.

Their exceptional orientation abilities ensure that they can find their way across vast oceans to return to the natal beach to nest; however, when subject to heavy exploitation, breeding becomes extremely difficult and it takes a long time for a depleted population to bounce back, as there is unlikely to be any “recruitment” from other, healthier populations.

Another special adaption of sea turtles is that their sex is determined by the temperature at which their eggs are incubated. If the incubation temperature is below 29 degrees Celsius, males, predominantly, will be produced, while only females will be produced at temperatures above 30.4 degrees. Rises in temperature resulting from climate change pose a great uncertainty for their future survival.

Green turtles migrate long distances from their breeding sites to feeding grounds, which increases their chance of coming into harm’s way. Satellite tracking by Hong Kong’s Agriculture, Fisheries and Conservation Department shows turtles can travel several hundred kilometres from Hong Kong, to waters near Hainan Island , eastern Guangdong and Vietnam. Adults feed mainly on algae and sea grass but also eat some invertebrates. They often mistake pieces of floating plastic for squid. Today, ingestion of non-digestible plastics is a common cause of sea turtle death.

Hong Kong’s nesting green turtle population now probably consists of just a few adult females. Some years may see zero nesting activity.

In 1999, the government established Sham Wan as a restricted area, with no entry allowed without a permit during the nesting season. The fisheries department also patrols the nesting beach, and when natural incubation of the eggs is deemed too risky, artificial incubation will be carried out.

These efforts have resulted in baby turtles being hatched successfully either naturally or artificially.

However, the weakest link in conserving this species here is that the coastal waters adjacent to the nesting beach at Sham Wan are not protected and are subject to disturbance from people engaging in water sports.

It is in these same shallow waters that male green turtles will wait for the females – to mate with them before they lumber up the beach to lay their eggs.

The waters around South Lamma were identified as a potential marine park or reserve in a previous planning study. Indeed, with the Convention on Biological Diversity being extended to Hong Kong in 2011, we have a responsibility to contribute to the convention’s biodiversity targets, one of which states that 10 per cent of coastal and marine waters should be conserved as protected areas by 2020.

To save the remnants of our green turtle population, we should spare no effort to protect the waters off Sham Wan and give these turtles space and time, and thus the best possible chance, to recover.

Michael Lau (senior head of programme for local biodiversity & regional wetlands at WWF-Hong Kong).