Every year, thousands of whales, dolphins, porpoises and dugongs/manatees strand on beaches all over the world. They may strand alive or dead, alone or in groups, and while some animals may be unhealthy, even healthy animals can strand due to injury or disease. This is a natural phenomenon and has been happening since time immemorial. Stranded animals provide a wealth of information that can help scientists and managers address marine mammal conservation concerns.
Dead animals on the beach could result from boat or ship strikes, fisheries gear entanglement, oil spills, disease, toxins, contaminants, predation or disorientation or ear injuries due to exposure to noise from construction at sea or sonar activity. Live strandings could occur for some of the same reasons. The animals might have simply survived the incident and ventured into very shallow waters. A stranding might result from species-specific social behaviour, especially a mass stranding. Many theories have been put forth to explain strandings. One theory is that changes in the earth's magnetic field cause an animal to lose its sense of direction. Cetaceans may have an extra sense called biomagnetism, which enables them to detect variations in the earth's magnetic field. They may use the magnetic field, like a map, to navigate. The field is always changing, and so, occasionally, they could become confused and swim towards the shore.
Alternatively, an earthquake or storm could cause a cetacean to panic; a brain infection may cause disorientation; the animal's sonar system may fail; or it may simply get lost or feel sick and need to rest. In mass strandings, the whole group may be in trouble in some way, or the animals may be following one animal that is ill or disoriented.
Some dolphins maintain strong social bonds (for example, pilot whales), which require group cohesion and communication, and when one animal in the pod (family) strands, other memers may also strand. In most cases, live stranded animals may not survive even with assistance. But they could be returned to sea swiftly following human safety measures and limiting animal stress.
Rehabilitating dolphins and whales is often a costly exercise, and therefore considerable discussion and evaluation by marine mammal experts and the Forest Department is needed to decide the best course of action.
How to Deal with a Live Stranded Animal
If you find a stranded animal, inform the local police or Forest Department official first. All marine mammals are protected under India's Wildlife Protection Act of 1972. If the stranded animal is alive, get expert help before trying to make it more comfortable. If it is dead, do not touch the carcass. Cordon off the area from curious onlookers and maintain a perimeter of at least 25 metres from the carcass. Gloves and masks must be worn when in contact with any animal because of the risk of transmission of diseases.
- Find out if the animal is still alive – This is typically indicated by movements of the animal's tail or body and breathing, though the breathing could be lethargic and infrequent. If the animal is alive, it needs to be provided supportive care. If it is still in the water, make sure the blowhole is not covered and the animal can breathe. If possible, count and note down the number of breaths per minute--typical rates for dolphins are 4--5 breaths per minute. Monitor the animal until a veterinary professional or expert is there to attend to it. Small dolphins and porpoises may be supported by hand, but extra precautions need to be taken to handle a whale. Care must be taken not to damage the animal's skin, which is delicate. Make certain that the animal never lies on its own flippers or is upside down as this can restrict circulation and affect survival. Ensure that sand or water does not enter the blowhole.
- Erect a shelter to provide shade - The greatest problem facing a stranded cetacean is over-heating. Build a make-shift shelter to provide shade. Do not apply sunblock lotion to the animal’s skin.
- Keep the animal’s skin moist – A stranded animal is susceptible to sunburn and over-heating, even in cold weather. Cover the animal’s body with a light wet sheet or towel, and keep these moist by pouring water over them. Take care never to cover the blowhole or to pour water into it. It is vital to get expert help as quickly as possible.
- Keep the area around the animal quiet – Since the animal is in extreme stress, it is important that people do not crowd around it. Only essential persons needed to provide supportive care should be near the animal. Media persons and the public should be provided guidance, an explanation of what has occurred and what will be done to avoid confusion and misinformation.At night, make certain that no lights or flash bulbs are shone directly into the eyes of the animal. Maintain limited contact with the animal. Always approach an animal from the front or side so that it can see you.
- Move the animal very carefully – Never push or pull on the flippers--these are very easily injured. Try not to touch the head or the tail flukes. Never roll the animal on to its side underwater or use any hooks or crowbars. The most effective way of moving a small cetacean is with a sling, which can be improvised from towels, blankets or tarpaulin. Since the animal is likely to be heavy, mobilise sufficient manpower. Carry the animal into water deep enough to support its weight and release the sling once it is clear that the animal can keep itself upright and swim.
How to Deal with a Dead Stranded Animal
- Take photographs that capture the animal from all sides and angles. It is necessary to takephotographs at the level of the animal and at 90 degrees to it. Take a long shot of the animal and close-up pictures of its head, jaw, dorsal fin, genital area and tail fluke. Take photographs of the dorsal (upper) and ventral (lower) views. Take pictures of ventral slits--these can help determine whether the animal is male or female. Also, photograph any markings, injuries or wounds.
- Note the time, date and location of the stranding event. If a GPS is not available, note down the nearest landmark and upload the information to the database on this website. Also, share your information through the 'Marine Mammals and Turtles of India' Facebook page to get help with identifying the species.
- Record comments on the condition of the animal when it is first sighted, whether it was alive or dead any other relevant information about the stranding, for example, any evidence of the animal having been affected by fishing gear. Many cetaceans change colour after death, sometimes within a few hours, and therefore false impressions may be obtained of the true colouration.
- After photographs and measurements have been obtained and authorised (permitted) biological sample collection, if any, carried out, the animal should be buried at an appropriate location. Depending on the soil conditions, skeletons can be recovered in time and used for educational purposes.
- Download the document "Cetacean Carcass Data form 2012" to collect data and as a short guide to handle carcass
Information from Strandings
For many years the only information available on cetaceans has been gleaned from strandings. Despite several studies having been conducted, some species have never been seen alive, and many others are almost impossible to distinguish at sea. So stranded animals provide vital clues about the life history of marine mammals and threats faced by them, and they offer a low-cost solution to collecting scientific data from rarely seen animals. An examination of a dead specimen may be necessary for a positive identification. Stranding provides the opportunity to examine a cetacean’s teeth. The size, shape, number and location of a cetacean’s teeth can be very distinctive and helpful in identification.
Skin/blubber and tissue samples can be used for histopathologic, genetic and contaminant analysis, which can tell us more about the animal and why it died. Appropriate permits from the Forest Department are needed for any research sampling.