"Say NO to Overfishing"
DOLPHINS < OMAN ENVIRONMENT

Dolphins and Whales*
WHALES and dolphins worldwide need protection as they face many threats from people. Oman has played an important role in stopping international whaling and is the only country in Arabian-peninsula to be a member of the International Whaling Commission that bans the hunting of whales.

Oman is also a strong supporter of the International Union for Conservation of Nature and Natural Resources.

The Sultanate also enforces the global ban on hunting and killing of these marine mammals and secure and conserve their natural habitat.

As a result of these efforts the Sultanate has gained a respectable position among nations concerned with environmental protection.

There are a few things to bear in mind when interacting with dolphins or whales. They are wild animals and one should respect their needs.

In order to do so, always let the whales or dolphins choose how they want to interact with you. This means: Do keep a distance of 100 metres for whales and 50 metres for dolphins.                                                        Toothed cetaceans of Oman

Do let them come closer and do not force yourself on the animal. Always remember: the animal can dive, you cannot. Do turn off your engine or let the motor idle, if the whales or dolphins become curious and decide to come closer and have a look at you. Do keep a predictable course and do not separate groups. Do not speed towards them but approach slowly at a constant speed from a parallel position or from behind. Do not speed through groups. Do not try to chase or herd animals. Do not try to feed them or throw rubbish into the water. How to identify a dolphin or a whale?


 

 

 

 

Identification of whales or dolphins in the open sea is not easy. Most of the time they remain hidden from view. If they surface to breathe, the intervals are often too short to see much of the animal. For the inexperienced spectator dolphins and whales look almost the same at first.

However each animal has distinctive features which enable its identification. To identify an animal it is best to run through a mental checklist of the features described below.

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Crucial features for dolphins and whales are their colour and colour patterns (are they light or dark, brown or blue, do they have dots etc). Colour, however, can vary with light conditions and the colour of the water.

Size is another relevant feature for the identification of different species of dolphins and whales. It is, however, very difficult to estimate the size correctly from a distance and while the animal is moving. Even rough estimates can be of some help for identification though.

Also size, shape and colour of the dorsal fin (which is often visible), fluke and flippers can help to positively identify an animal. The location of these features on the body also varies greatly from species to species.

Flukes are sometimes lifted high into the air before diving and can be of great help in the identification of these animals. Overall body shape can be used as an identification feature, though one rarely gets to see the whole animal.
                                                                                

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A feature much easier to assess is the beak. It can be used for identification. There is also some variation in the way in which different dolphin and whale species dive and come out of the water.

Behaviour in a very general sense, that is whether the animal bowrides, lobtails, leaps and so on and how it performs these actions, can serve to indicate the species. Dolphins and whales are more social animals. Group size can therefore be taken as an indicator for a certain species.

A feature especially useful for identification of larger whales is its blow. Its height, shape and visibility can be used as the sole feature needed for identification.

How to identify dolphins fish?
Despite the fact that they live in the ocean, dolphins are warm-blooded mammals that breathe and suckle their young.

 

 

What is the difference between dolphins and whales?

There is a difference between what we call a whale and what biologically is a whale. We tend to use whale for larger mammals living in the sea. Whales have baleen whereas dolphins have teeth. Killer whales for instance therefore are technically dolphins.

What do they eat?
Dolphins feed on most kinds of fish, including mullet, whiting, snapper, tuna, bream and invertebrates such as squid.

How do they sleep?
Dolphins sleep on the surface with only the blow hole exposed. Dolphins are ‘conscious’ breathers, which means that they have to be awake or semi-conscious to breathe, otherwise they would drown.

They doze for a few minutes at a time, and their blow hole periodically opens and closes by reflex action.

They sleep in a semi-conscious state, resting one side of the brain for a short time then swapping over. This technique also allows them to be aware of any dangers.

How deep can dolphins dive?
Bottlenose dolphins can dive to depths of 21 metres and even to 30 metres. Risso’s dolphins can dive to over 1000 metres.

Why do they jump?
There are four probable reasons that dolphins jump: either to play, for communication with other dolphins, to get rid of parasites, or to get a better view over the water.

Do they migrate?
Some species of dolphins migrate. Some species travel hundreds of kilometres in circular territory, probably for food.

What is their gestation period? Gestation lasts for 10 to 12 months.

How long do calves stay with their mothers?
Calves stay with their mothers up to five years or longer. Mothers are very protective and keep the calf at their side at all times during this period.

What do their sounds mean?
Dolphins use sound (ie sonar or echo-location) to find objects and hunt for fish. These sounds are of high frequency and send out at a rate of several hundred per second.

The sounds bounce off objects in the water and are picked up by special tissue in the lower jaw of the dolphin which conducts the echo through to the inner ear.

This allows dolphins to identify objects without having to touch them. Dolphins also sometimes use their sonar to stun fish. They also use sound to communicate with one another.

How long can dolphins stay under water?
For periods of up to 1 hour, although five minutes is usually the average.

Can we see dolphins even when the sea is rough?
No, we cannot since dolphins usually avoid the surface when the sea is rough.

Do dolphins look after their sick?
They are known for doing so, although this behaviour has rarely been observed in the wild. Dolphins stay underneath and at the sides of the sick and by doing so keep them close to the surface so that they can breathe.

However, they do give up after some time. Dolphins have also been observed swimming away from another dolphin entangled in a net.

How intelligent are dolphins?
Since no one has come up with a method to successfully rate the intelligence of a human being, measuring the intelligence of other species has proven difficult if not impossible.

The evaluation of dolphins’ intelligence is especially difficult, because they are adjusted to an entirely different medium, ie water. However, we can say that dolphins are fast learners and are able to generalise and learn sign language.

Are whales local or migratory?
Most whales are migratory and travel to the poles in the summer and back to warm temperate waters in winter. Some populations are resident though.

Are whales and dolphins happy in captivity?
No, not at all. In captivity, the average age for dolphins is 6 years. They tend to develop disturbed behavioural patterns too. Some countries, for example Britain have given up keeping dolphins in zoos.

Can you feed dolphins and whales?
No, you should not. Feeding them will change their food behaviour and will have a detrimental effect on the marine life in general. If you feed dolphins or whales, you interrupt the natural food chain.

How long is the gestation period for whales? It is between 10 to 13 months. Whales give birth to a calf every 2 to 3 years.

How long is their lactation period? The calf is fed for 3 to 9 months.

How many calves do whales have? Whales gives birth to one calf at a time.

How long do whales stay underwater?
They mostly stay underwater for 3 to 8 minutes. However, longer periods of up to 30 minutes have been recorded.

Can whales and dolphins communicate across species?
They understand basic elements of other dolphin or whale species behaviour, some to the extent that they interbreed like rough toothed and bottlenose dolphins.

Are whales and dolphins aggressive and dangerous?
Most dolphin and whale species are peaceful and rather shy. So far humans have proven to be of greater danger to whales and dolphins than the other way round.

However, some species like killer whales and pygmy killer whales can become aggressive. They are much less aggressive than their names imply though. If you go diving with whales, the danger is mostly because of their size. They might harm you without intending to do so.

Why do whales strand?
There are different theories on this issue. The most recent evidence suggests that whales strand if their hearing is impaired by loud noise which can be caused by the Navy’s sonar systems for instance.

Why are killer whales called killer whales?
They are called killer whales due to the fact that they feed largely on warm blooded prey. They hunt even whales occasionally, therefore the name "killer (of) whales".

Why are sperm whales called sperm whales?
Sperm whales were hunted for spermacetes, a substance found in their heads which was used to the production of perfumes, candles and ointments.

How well do whales and dolphins hear and see under water?
Whales and dolphins hear very well underwater, though not in air. A human being’s hearing ranges from 40 Hz to 20 kHz. Dolphins use very high sounds for echolocation, so they can hear sounds as high as 150 kHz. Low sounds travel very far underwater, so whales can hear up to 20 Hz.

Their sight, however, is not very good, as it is not very important underwater. In deeper waters there is darkness. Dolphins and whales, therefore, navigate by their hearing instead of their sight.

How can we distinguish a male whale from a female?
At sea it is difficult to distinguish the two. Among baleen whales, females tend to be larger than males. Toothed whales males tend to be larger. They might also have other distinguishing features such as larger melons, larger dorsal fins or distinctive teeth.

Watching wild dolphins is a thrilling way to start the day and the lucky may even come across one of the many species of whales that can be found just a few kilometres from Muscat’s rugged coast.

Not every trip guarantees a sighting, but you are sure to enjoy a trip out to sea and enhance your knowledge of nature’s most fascinating marine mammals with the Arabian Sea Safaris on-board cetacean specialist, who will give a brief presentation on Oman’s whales and dolphins and help you understand their behaviour, ecology and lifestyle.

Subject to availability, also provided will be underwater hydrophones in order to hear the beautiful whale and dolphin songs. A special activity is provided for children to help their identification of species.

* Adapted from Oman Observer Newspaper. Nizwa.NET is not responsible for errors.