DOLPHIN INTELLIGENCE by Dr Gerry Goeden

There are many times that dolphins have rescued swimmers or fought off attacking sharks at real risk to themselves. Because of these actions, humans tend to feel there is a special bond between dolphins and themselves and that this bond is based on mutual intelligence or a wished for understanding.

From as early as the 17^th century scientists have been impressed by the size of dolphin brains and rated them near the top of the ‘non-human’ intelligence list. Many cetaceans (whales) do have large brains and, relative to body size, toothed whales have larger brains than baleen whales. In fact, the relative brain size of bottle nose dolphins is nearly the same as that of humans. Dolphin brains range from about 0.25% to 1.5% of their body weight and human brains are about 1.9% of our body weight.

Another measure of brain development is based on the number of folds in the grey matter (cerebral cortex). This is the part of the brain that gives us conscious control of our bodies and thoughts. Toothed whale brains have more folding than baleen whales but much of this is taken up for sound production and processing. Toothed whale brains, like the dolphin’s, have folding that resembles that of hoofed animals like horses and deer.

We don’t know if dolphins have a language but we do know that they share information about their surroundings, their emotions, and their identity through acoustic whistles and clicks.

Memory experiments with dolphins showed that their picture of the world and their ability to remember it was better when based on their sonar and not so good when based on sight. Their memory was best when they could use sonar and sight together.

Dolphins have also been taught ‘words’(using hand signals) that can be put together in two-word sentences like “get ball”. Scientists found that they understood these sentences about 80% of the time. Able to grasp the basics of human language, it may be possible to communicate in two and three word format with dolphins in the future. If we do decide to talk with dolphins it will be best to choose our subjects wisely since research shows a large variation in ‘intelligence’ among species.

We think of intelligence as the ability to understand our surroundings and process information so that we can react in the most favorable way. In this way intelligence is not the same as instinct where reactions are ‘pre-programmed’ in the brain. In the animal kingdom, species with higher intelligence tend to be social animals that live in groups.

It is thought that the evolution of intelligence is related to the need to understand group dynamics and the individual’s place within them. The ‘smarter’ dolphins operate in social structures similar to dogs and primates.

Having a well developed brain and intellect; humans are always quick to make lists showing the relative intelligence of other animals with us at the top. To be fair, we must always ask the question: “How intelligent would we be in the dolphin’s world of sound and social behavior; in a world without landmarks and signs; and without shelter and an organized food supply?”

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DOLPHINS IN CAPTIVITY

One of my best friends over the years was a marine mammal veterinarian. He looked after the health of animals like dolphins, sea lions, and whales while they were in captivity. A great but very controversial job!

Because all of the marine mammals are fairly intelligent, they require stimulating environments. Over the years many people have come to believe that being held in captivity just doesn’t meet those requirements and that these ‘more cognitive’ animals need to lead more acceptable and ‘freer’ lives.

We often talked about the pros and cons of marine mammals in captivity; and yes, there are pros and cons but these seem to be shifting toward the negative and so collecting and moving marine mammals is now very difficult. Most new additions are offspring of those kept in captivity for many years.

Let’s look at the arguments.

First let’s look at some of the biological questions;

Q. Dolphins eat fresh food in the wild but in captivity, they have to eat frozen seafood. Does that affect the dolphin's health?

A. Dolphins are aggressive predators and spend as much as half of their time hunting. In captivity, they don't have to do this and miss out on some of their behavior. 'Fish' is frozen not only to make it easier for aquariums to store but to kill parasites that invade the dolphin's digestive system in the wild. Frozen seafood is also supplemented with vitamins and minerals. Dolphins are too expensive for aquariums to risk their health because of bad food. I would say that they eat as well or better in captivity.

Q. How big would a tank have to be to keep dolphins in captivity?

A. This is a difficult question because in the wild, there really aren't any border; dolphins can go where they like and travel great distances. In the wild they can swim up to 200 km a day and some species spend much of their time in very deep water. Others like the Chinese Humpback dolphin don't move around much in the wild and stick to the familiar surroundings.

Q. Are dolphins physically stressed when they live in captivity?

A. Dolphins are highly intelligent animals and live in complex social groups. It is argued by aquariums that dolphins live longer in captivity due to less disease and predation. " Pro-dolphins groups argue that they live longer in the wild because they lead more natural life and belong to social groups. Stress and odd behaviors are sometimes seen in dolphins held in aquaria but then they aren't subject to shark attacks and parasites either.

Q. Is it a good idea to put different 'kinds' of dolphins in the same tanks?

A. Captive dolphins often come from different regions and populations. While wild dolphin groups do stick together, there is quite a lot of movement of individuals between groups. If this were not so then dolphins would quickly become inbred and genetically weakened.

Dolphins in captivity sometimes share tanks with other marine mammals but this is avoided by better aquariums. Competition and fighting between species damages the animals and my friend's medical work was very expensive.

Now lets look at some of the ethical questions that relate to keeping intelligent animals in captivity;

Q. Do dolphins enjoy performing in shows?

A. Because of their intelligence and social nature they do enjoy challenging activities (performing). Most of the performance behaviors are based on their natural behaviors and dolphins will not do them if they don't feel like it. They literally go on strike. Left alone, they will play with balls and hoops just as they will play with debris and seaweed in the wild. Another question could be "Do dolphins prefer to play with balls in captivity or seaweed in the wild?" My guess is they would find the wild much more interesting.

Q. Dolphins and other marine mammals have very large brains so are very intelligent. Do they suffer mentally in captivity?

A. The Indo-Pacific Bottlenose Dolphin (Tursiops truncatus) has an absolute brain mass of 1500 - 1700 grams. This is slightly greater than that of humans (1300 - 1400 grams) and about four times that of chimpanzees (400 grams). They are intelligent but most of that brainpower goes to processing underwater sound and echo-location. Our best estimate is that they are of similar intelligence to elephants and some apes. So, yes, they would suffer if they didn't get a stimulating environment. we don't know if they long for the wide open spaces.

Q. Are dolphins forced to live in mentally stressful situations?

A. While aquariums do their best to remove stress, the fact is that limited space and social interactions take their toll. Dolphin males spend a lot of time fighting over females and the loser finds it easier to get away in the wild; there can be more damage through continued aggression in aquaria IF the managers don't keep competing animals apart. Unnatural social relationships are probably the biggest mental problem faced by dolphins in captivity.

Q. Would dolphins escape if they could?

A. An interesting question. The U.S. Navy uses dolphins to search the bottom of ships for explosives, locate mines in harbours, and ‘spot’ enemy divers. The dolphins are released from captivity and go off to do their jobs. When they are finished they return to captivity.

My friend, the marine mammal veterinarian, says that like dogs dolphins build bonds to humans and see us as their ‘family’. And like dogs they come home after they have been released.

Have a look at some of the photos of his work with dolphins.

Prior to 1980, more than 1,500 bottlenose dolphins were collected from the United States, Mexico, and the Bahamas, and more than 550 common and 60 Indo-Pacific bottlenose dolphins were brought into captivity in Japan. By the late 1980s, the United States stopped collecting bottlenose dolphins and the number of captive-born animals in North American aquariums increased from only 6 percent in 1976 to about 44 percent in 1996. It is well over 50 percent now.

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