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Stranding Records in Hong Kong |
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From the beginning of the stranding programme in 1973 till now, there are nearly 300 stranding records of 16 species of cetaceans in Hong Kong. Investigating stranded cetaceans can give us a better understanding of their cause of death and allow us to obtain information that cannot possibly be collected from live animals. |
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Why do cetaceans strand? |
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Stranding means that cetaceans, which naturally live in waters, run aground and cannot return to water for some reasons. There are two types of strandings: dead stranding and live stranding. Dead stranding occurs when a cetacean dies of old age or an illness, and then its carcass is washed ashore; while live stranding means that the cetacean is still alive when it strands. In Hong Kong, most strandings are the dead ones. |
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There are various speculations of why cetaceans live strand. The following are some reasons of why oceanic and coastal species live strand: |
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| Besides, a variety of peculiar theories of why an oceanic cetacean species live strands arise. Until now, there’s still no confirmed explanation for this phenomenon. |
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Belugas, which reside in the Arctic area, will rub their body along the gravels or sands at the seabed in shallow waters when they begin to moult. Nonetheless, if they are unable to return to deeper waters before the tide recedes, they will strand. This is not always deadly as some can tolerate till the next tide returns. |
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| Besides those singly stranded cetaceans, some species with strong social bond, like pilot whale, sperm whale, false killer whales and rough-toothed dolphins, may strand en masse. Till now no mass stranding has occurred in Hong Kong, but this is rather prevalent in some nations like the Australia, New Zealand, UK and US. Scientists believe that a pod of these species is usually led by a leader. But if the leader strands for some reasons, other healthy members may follow the leader to shore. Some individuals are so healthy that can be returned to sea right away when they strand. However, some of these may re-strand or be unwilling to swim away. It is believed that they don’t want to leave their companions, but this is to be confirmed by further research. |
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What should we do when we see a stranded whale/dolphin? |
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You should contact AFCD promptly at the 24-hour stranding hotline at 1823. The following details would be very useful for AFCD: your name, contact phone number, the date, time and precise location where the carcass is found, body feature (e.g. colour and size) and its decomposition state. |
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| In fact, investigating beached cetacean carcass is a vital part of cetacean research. The data and samples obtained provide much information on the cetacean biology. Take beaked whale as an example. Beaked whale is a group of cetacean that only occurs in deep sea. The worst of all, beaked whales are very elusive, so human knows almost nothing about them. Most of our knowledge about beaked whale actually comes from their carcasses washed ashore. |
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What samples do researchers take from stranded animals? |
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After receiving stranding report, a research team will immediately be dispatched by the AFCD to the stranding location for data and sample collection, which are used for further analysis. Upon arrival, research team members will start to investigate the carcass. They will identify its body features, confirms its species, and take photos of it for record. Then its body length will be measured. Afterwards, a series of samples will be collected, including skin (for stock structure study), teeth (for age determination), blubber, liver, kidney (all three are for ecotoxicological study), stomach (for feeding habit analysis) and skull (for stock structure study and educational display). Lastly, they will try to find out its sex. From the necropsy, researchers can learn more about the life history and cause of death of the cetacean. |
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Can the public get involved in cetacean rescue? |
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| Generally, members of the public should not touch any beached animal, as only veterinarians and cetacean researchers are acquainted with the professional knowledge and experiences in dealing with stranded cetaceans. In some foreign nations, stranding rescue team members are even required to attend recognized training courses and obtain related permits. |
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| Stranded cetaceans are wild animals that carry various kinds of germs, viruses or parasites potentially transmissible to human. Also they may thrash with their powerful flukes abruptly or even bite. Therefore, it’s safer for the general public to be on-lookers only. If you’d like to be a volunteer to help, get permission from the rescue team first, and follow their instructions. |
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| Before the rescue team arrives, please do not surround the live-stranded animal, make any big movement and loud noise, and let any animals like dog get near it, as all these will irritate the animal. Also, do not attempt to touch and handle the stranded cetacean. Remember, never push the animal back to sea on your own. Animals strand only when they are ill. Returning the animal to sea without veterinarian’s advice will probably delay proper diagnosis and injure it more. |
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| Besides, a sick cetacean pushed back to sea usually re-strands. If the stranded cetacean is in an acute situation, e.g. its blowhole is submerged in water so that it cannot breathe, please contact the rescue team to consult if any preliminary rescue action can be made. |
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How do researchers deal with live-stranded cetaceans? |
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In Hong Kong , live stranding is rare. In general, there are three ways of dealing with live-stranded cetaceans: |
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| 1) Return it to sea |
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| When it is confirmed by veterinarians that the live stranded cetacean is trouble- and disease-free, and the environmental condition permits, the animal can be returned to sea right away. Before release, cetacean researchers will measure its body length and collect some of its skin sample for further investigation. They may then put a radio or satellite-tag on the cetacean dorsal fin for monitoring its status after release. |
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| 2) Rehabilitate it in a nearby aquarium or other appropriate care facilities |
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| There is no animal hospital especially for cetacean in Hong Kong as live stranding is not common in the territory. So transporting the animal to an aquarium is the only feasible way in Hong Kong. In this kind of facilities, the stranded animal will be put in a shallow pond, in which it will receive treatment and care from the vets and researchers. There’s usually a laboratory beside for pathological study. In foreign nations, recovered individuals will be returned to the nature. |
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| 3) Euthanize it or let it die naturally |
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| When the survival chance of the stranded cetacean is considered too slim by vets, or any rescue is not logistically possible, euthanasia remains the only way to end the animal’s suffering. As all cetacean species are protected in Hong Kong, euthanasia can be carried out by AFCD vets only. There are a number of euthanizing methods, among which using syringe or needle is the most widely used worldwide. However, if the cetacean is too huge (e.g. blue whale), or no vet is available, euthanasia will not be realistic anymore. In this case, what rescue team can do is to let it die naturally. |
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There are a couple of criteria that the researchers need to think about before making decision on what kind of action is to be taken: |
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| Size and Number of live stranded cetacean |
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| The opportunity of rescuing a smaller cetacean would be higher. For example, a 1.5 m-finless porpoise can be easily handled and held by several men, and put in a vehicle for transportation. But a 10-m Bryde's whale cannot. Number of animals also counts. If 20 pilot whales strand at the same time, it is not possible to transport all to an aquarium with limited resources. In this case, those in worse situation might be euthanized. |
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| Physical Status |
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| Sometimes the body state of a live-stranded can be easily observed from its outer appearance, but only a detailed veterinary investigation can confirm it. Usually those severely ill or injured, aged and orphaned maternally-dependent can hardly survive. Most strandlings belong to this group, which would be best euthanized for the sake of their welfare. |
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| Environmental condition |
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| This refers to weather condition, temperatures and sea state. If the weather is fine with moderate temperature and calm sea, the stranded cetacean will be less stressful, and the rescuers can handle and transport the animal with much ease. The survival rate of the strandling can thus be heightened. |
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| Logistical support, transport and care available |
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| This depends much on the local resources available. Advanced countries with more cases of stranding occurring will usually allocate more resources to cetacean rescue; but in those developing nations where no animal care facilities ever exist, cetacean rescue is not viable. |
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Why save stranded cetaceans? |
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| From the view of conservation, rescuing stranded cetaceans of endangered species, and returning it to its habitat after it has recovered help save them from extinction. To those species with only several hundreds members left in the world (like northern right whale and baiji), rescuing an individual is already a great good news to their entire species. |
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| However, cetacean species that had stranded alive in Hong Kong, including Chinese white dolphin, finless porpoise, false killer whale and sperm whale, are not internationally threatened at all. Thus, saving an individual of this kind has nothing to do with the species or wild population conservation. This is often based on human's passion for cetaceans, and their curiosity for their biology and pathology. |
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In fact, many of our dolphin knowledge come from these saved stranded marine mammals. Also, the technique for cetacean rehabilitation might one day be applied on helping those cetaceans of endangered species. |
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Survival rate of stranded cetaceans | |
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In general, cetaceans only beach when they are in serious trouble, so only very few can survive. According to past records, only less than 10% of stranded cetacean could survive nation-wide. Experiences from the aquariums in many nations showed that most of the cetaceans saved from the wild would finally pass away. However, this doesn’t mean that the rescue effort went in vain. The carcass can still provide much information. The researchers will do a detailed necropsy on the dead cetacean to find out the cause of death. And the researchers can certainly learn from experiences to help other stranded cetaceans. |
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