On the 29th of June (2017) the AFCD (Agriculture Fisheries & Conservation Department) released 10 green turtles (Chelonia mydas) and one hawksbill turtle (Eretmochelys imbricata) in the southern waters of Hong Kong.
The turtles were among the 35 green turtles and one hawksbill turtle seized from a fish raft in Sok Kwu Wan Fish Culture Zone (Lamma Island) in September 2016.
The 10 green turtles and the hawksbill turtle weighed from 11.5 kilograms to 61 kg and measured about 45 centimetres to 82cm in carapace length. All of them were assessed by veterinarians of OPHK as being in good condition and ready to be returned to the sea. The other green turtles were already released in November 2016.
Before the turtles were released to the sea, they were tagged with a microchip and Inconel tags for future identification. Satellite transmitters were also attached to the carapaces of the turtles. By tracking the movement and feeding grounds of green turtles in the sea, the AFCD can collect data for formulating appropriate conservation measures and share its findings with other conservation authorities for the better conservation of sea turtles. Satellite tracking revealed that the some of the turtles released in November 2016 headed south to the South China Sea via different routes, reaching Wanshan Archipelago, Dongsha, Nansha and Xisha Islands, Hainan Island and as far as Malaysia.
The green turtle and the hawksbill turtle are globally endangered and critically endangered species respectively. In Hong Kong, all sea turtle species are protected under the Wild Animals Protection Ordinance and the Protection of Endangered Species of Animals and Plants Ordinance . 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.
The AFCD seized 36 live sea turtles from a fish raft at Sok Kwu Wan Fish Culture Zone on Friday (September 30).
Upon receipt of a report of sea turtles found on the fish raft from the Police, the AFCD officers were deployed to the scene for investigation and they seized 35 green sea turtles and a hawksbill turtle.
All the sea turtles were sent to Ocean Park Hong Kong for observation and detailed veterinary assessment and follow-up investigation by the AFCD is ongoing.
To report suspected irregularities, call the government hotline at 1823.
A dead finless porpoise (Neophocaena phocaenoides) was found in Discovery Bay on Sunday afternoon, the fourth dead marine mammal discovered in four days after the bodies of three dolphins were discovered on Thursday.
It was found in the water and handed over to the Ocean Park Conservation Foundation for an autopsy. The OPCFHK said that the porpoise was a 1.55 metre long female and the body had reached the fourth stage of decomposition. Its cause of death has yet to be determined.
On Thursday, the bodies of three Chinese white dolphins (Sousa chinensis) were found – one entangled in fishing wire near Lido Beach in Sham Tseng, one in waters near Lamma Island and another in Fan Kwai Tong off Lantau Island.
The Hong Kong Dolphin Conservation Society (HKDCS) estimate that there has been a decline since 2014, when 61 dolphins were estimated to be in Hong Kong waters.
A wider restricted area in southern Lamma would keep out the noisy junk parties that threaten the nesting site of rare creatures
It’s a sunny September day and half a dozen junks and pleasure boats are anchored in a scenic inlet on southern Lamma Island.
House music is booming and banana boat-tugging speedboats zip across the bay, while those with the energy make the 50-metre swim to shore – unknowingly committing an illegal act by frolicking on the sandy shores of Sham Wan beach.
The beach is one of the few regular nesting sites for endangered green sea turtles in southern China and is a restricted area during the breeding season between June and October. It was designated a site of special scientific interest in 1999.
Illegal entry is liable to a maximum fine of HK$50,000, but that’s only if nature wardens are able to stop such violations.
Scientists and green groups want the Agriculture, Fisheries and Conservation Department to ramp up protection efforts by expanding the 0.5-hectare restricted zone to the entire bay to keep out junk parties.
A study by the Eco-Education and Resources Centre between 2013 and 2015 recorded anywhere between 12 and 17 boats anchored in the bay at weekends. Average noise levels went as high as 80 decibels, similar to a police siren, in some parts of the bay.
Green turtles are known for their migratory behaviour and loyalty to feeding sites and nesting grounds. Tracking efforts show they usually swim to Wanshan Archipelago, Fujian waters, the Pratas Islands, the Spratly Islands and the Philippines after visiting Hong Kong.
“Nesting sea turtles are easily affected by human activity,” said ERC science manager Dr Michelle Cheung Ma-shan.
“If a turtle is put off from approaching the beach, it will be forced to lay its eggs underwater, where they will die.”
There have already been notable drops over the years. Between 1998 and 2006, there were 14 records of nesting turtles in Sham Wan. But only two have been documented since 2006, with the last sighting in 2012.
Floating markers similar to ones used in marine parks could be set up to demarcate the entire bay as a protected area.
The ultimate goal is to establish a marine park in hopes that strengthened conservation efforts can bring back sea turtles in greater numbers, says Ken Ching See-ho, the ERC’s founder and director.
“The first step is to expand the restricted area under the Wild Animals Protection Ordinance.”
Cheung said nature wardens should be patrolling the beach to keep people out, but their field studies showed they were only present about “60 to 70 per cent of the time”.
Ching said the department could look to successful examples of turtle protection areas overseas, such as the Sandakan Turtle Island Park in Sabah, Malaysia, and a protected area in Taiwan’s Penghu Islands.
Green Power chief executive Dr Man Chi-sam said Hong Kong’s efforts at turtle conservation were “very behind” and “very passive”. “[The findings] also reflect the low public awareness and understanding of this species in Hong Kong,” he said.
A department spokesman said regular patrols were conducted in the area to control unauthorised entry and to monitor the nesting activities of green turtles. “We will step up patrols and put up more warning signs to alert the public not to enter during the restricted period.”
Hongkongers love their seafood – a quick glance at the local restaurants scene will more than proove that point. Per capita HK has one of the highest seafood consumption rates in the world. For many locals, expats and tourists a trip to Sok Kwu Wan on Lamma for a seafood meal would not be complete without a big steamed grouper (also called garoupa). But aside from concerns about over-fishing and sustainability, eating these fish can be a health risk, too. That is because these large reef fish are more likely than others to give you ‘Ciguatera fish-poisoning‘. Ciguatera (‘see-gwa-terra’) is a food born toxin harbored by large reef fish. Originally the toxin (CTX) comes from a microscopic organism called Gambierdiscus. Gambierdiscus is a dinoflagellate – a single-called organism with a thin shell and two beating hair-like whips called ‘flagella’ that move it through the water.
Gambierdiscus sticks to coral, seaweed and algae in tropical and sub-tropical regions (like HK) and is eaten by smaller fish feeding on the coral and algae. These fish in turn are eaten by predator fish and so the toxin moves up the food chain, finally accumulating in its greatest concentration in the large reef fish.
Tissues like the roe (fish eggs), head, skin and insides are particularly good at concentrating CTX. CTX is odourless and tasteless and very heat-resistant – so conventional cooking will not destroy or inactivate the toxin.
So how bad is CTX poisoning?
Ciguatera causes a combination of gastrointestinal, neurological and cardiovascular symptoms. The gastrointestinal symptoms include nausea, vomiting, abdominal pain and diarrhoea. That might not be that bad, right? But the cardiovascular symptoms are more serious: a slowing of your pulse to under 60 beats per minute (sinus bradycardia) and low-blood pressure (hypotension) which can be life-threatening but can also be treated. The common neurological symptoms include a sensation of tingling, tickling, pricking, or burning of a person’s skin, numbness of lips, tongue and the four limbs, reversal of hot-cold sensation, muscle pain, muscle weakness, joint pains, itching and fatigue and these symptoms can last for weeks or even months.
CTX in Hong Kong
Because ciguatera is a matter of food safety the HK government requires by law that the reporting of all diagnosed or suspected cases and as a result there are some good statistics on ciguatera in Hong Kong. From 1988 to 2008 there were between 3 and 117 outbreaks annually causing between 19 and 425 people to fall ill. Groupers were responsible for almost 60% of those cases, with snappers causing another 32%. The rest of the cases were caused by moray eels, triggerfish, parrot fish and other reef fish. Past records of ciguatera fish poisoning cases in Hong Kong show that the following fish are more likely to contain ciguatoxins: Moray Eels, Potato Groupers, Speckled Blue Groupers, Tiger Groupers, High Fin Groupers, Hump Head Wrasses, Areolated Coral Groupers, Black Saddled Coral Groupers, Lyretails, Black Fin Red Snappers, Flowery Groupers and Leopard Coral Groupers.
The most recent suspected case was in September 2014 when a 38-year old man became ill. Before that 19 people aged between 23 and 71 became ill after a shared seafood meal on Lamma in June 2013.
Ciguatoxin is very difficult to detect in fish samples so quality control measures are very difficult to implement and suspected cases are often not confirmed because either a sample of the eaten fish is not available anymore or chemical test are not able to detect the ciguatoxin well enough.
How to avoid CTX poisoning
To avoid this nasty CTX poisoning your best bet is to avoid large reef fish especially groupers. Any reef fish over 2 kg in weight is especially risky. And if you do chose to eat such fish stay away from the high-risk body parts of head (sorry, no more sought-after cheek meat), insides, skin and roe (eggs).
The HK government’s guidelines for the prevention of CTX poisoning are:
Buy coral reef fish from reputable and licensed seafood shops. Do not buy the fish if in doubt.
Consume less coral reef fish, especially marine fish over three catties (1.5 kg).
Only eat small amounts of coral reef fish at any one meal and avoid having a “whole fish feast” in which all the dishes come from the same big coral reef fish.
Avoid eating the head, viscera, skin, and roe of coral reef fish which usually have higher concentration of toxin.
When eating coral reef fish, avoid alcohol, peanuts or beans as they may aggravate ciguatera poisoning.
If you are suffering from ciguatoxin poisoning you should refrain from coral reef fish. The intoxication will sensitize patients and they will suffer from ciguatoxin poisoning even if they are exposed to a lower concentration of toxin.
Seek medical treatment immediately when symptoms of ciguatera fish poisoning appear. The unfinished fish should be brought to FEHD (Food & Environmental Hygiene Department) for testing.
Ciguatoxins are actually a group of about 20 chemically related toxins. The most potent of these is Pacific-CTX-1 (PCTX-1) which is found in the Pacific Ocean.
Ciguatera fish-poisoning was described as early as 600 BC by the Chinese and Captain James Cook’s log details effects felt by his crew on a voyage to Tahiti in 1774.
The clinical description of the syndrome came from Portuguese biologist Don Antonio Parra and were published in Havana in 1787. Parra said, “some [fishes] cannot be eaten because they are `ciguatos’ and some others are suspicioned because they carry with them the poison..I can speak from personal experience, because on 15 March 1786, twenty-two of us ate a Cubera, and we all developed those symptoms to a greater or lesser extent. All were prostrated, but each one was suffering various types of discomfort, although the most common type of difficulty was the extreme exhaustion accompanied by more or less pain. I observed that I had extreme difficulty in breathing, which caused great pain and a feeling of suffocation. My tongue became rough and I developed a sour taste in my mouth.”
This week red tides have been reported all across the western half of Hong Kong including Discovery Bay, Peng Chau, Mui Wo, East and West Lamma Channel. The culprit was once again the plankton species Noctiluca scintillans – neither fully plant not fully animal. It’s a single-called organism from a group called dinoflagellates. They consist of a bubble-shaped cell with two whips called flagella – that propel them through the water.
Though Noctiluca eats other plankton it doesn’t always kill what it eats: sometimes it leaves algae intact and stores it in little bubbles in its body (cell) where the algae make sugars that leak out and feed Noctiluca while the waste produced by Noctiluca feeds the photosynthesis of the preyed on algae – a process known to most as symbiosis and also found in tropical corals. However Noctiluca can also just eat the algae. Why and how it decides to eat or farm the algae is not really clear.
Noctiluca is a well known and non-toxic local red tide species and its occurrence is not necessarily a sign of pollution, but entirely natural. What is perhaps not natural is the size of the bloom, though. This could well point to agricultural fertiliser run-off and sewage effluent particularly from the fast growing population of the Pearl River Delta (PRD).
Images of the recent red tide at Discovery Bay North:
Noctiluca has however a redeeming feature – bioluminescence! That beautiful sea sparkle of iridescent blue that night divers in the tropics often sea or beach goers see in the breaking waves at night. So blood-red tides on the one side and beautiful sea sparkle on the other, Noctiluca is the Jekyll and Hyde of HK’s marine environment.
Long exposure image of a Noctiluca scintillans patch (cm via WikiCommons):
If you would like to know more about Actual toxic red tides in Hong Kong here is a little TV news documentary from 2013 I found on YouTube:
On Thursday (15th August 2014) red and shark flags were hoisted at two beaches on Lamma Island after a swimmer found a suspected baby shark that was about 50cm long at Hung Shing Yeh Beach. The flags were hoisted at Lo So Shing Beach as well due to its proximity to the location of the sighting. The Agriculture, Fisheries and Conservation Department later identified the shark to be a spadenose shark (Scoliodon laticaudus).
In a stunning display of massive overreaction, the Government Flying Service and the Marine Police to swept the area for any large fish or sharks, finding nothing, while a LCSD sonar search also found no sharks. The shark net was inspected and was found to be in good condition.
The two beaches will remain temporarily closed for safety reasons, while all other LCSD beaches and water sports centres have “enhanced vigilance”.