Don't keep dolphins in captivity

I REFER to the article, 'Another of Sentosa's pink dolphins dies' (ST, March 23).

I applaud the noble intentions of Sentosa's Underwater World to breed these dolphins in captivity.

However, I feel that the failure of the breeding programme undertaken by the marine park should hardly come as a surprise, given the high mortality rates of dolphins in captivity in other breeding programmes worldwide.

The average natural life span of a dolphin in the wild is between 25 and 50 years.

In the United States, more than half of all dolphins in marine parks die within two years of capture.

The remaining dolphins live an average of a dismal six years.

Captive-breeding programmes are not the solution for bolstering dolphin populations in the wild.

Dolphins simply do not fare well in captivity.

This could be due to a number of reasons, the first being that dolphins navigate by echolocation.

The dolphin's sonar waves are bounced off objects which lets it determine their shape, distance and location.

For dolphins held in enclosures or tanks, the sonar waves bouncing off the enclosure's walls become nothing more than a maze of meaningless reverberations.

It has been suggested that these reverberations can drive a dolphin to frustration.

Secondly, wild dolphins may swim distances up to 160 km a day.

This is obviously not feasible in captivity, thus encroaching on the dolphin's free nature.

Thirdly, given the failure of most captive-breeding programmes, a large percentage of dolphins in captivity come from the wild.

Wild dolphins swim together in pods, consisting of three to 10 individuals, or tribes of hundreds.

The dolphins in these pods or tribes follow a highly organised social structure.

Given the highly social nature of dolphins, the capturing of one dolphin can disrupt the entire pod.

Dolphins are also highly intelligent and sentient animals; therefore capture, and subsequent isolation from pod mates, can be said to be traumatic.

Dolphins in captivity do not behave the same way they do in the wild because, just like other animals in captivity, they lose their natural instincts.

It is stated in the article that Namtam's death was the result of gastritis, caused by the aggressive behaviour of Pet, a male dolphin that park curators had hoped she would breed with.

One can only speculate the reasons why Pet turned aggressive on Namtam, since so little is known about the habits and lives of the Indo-Pacific humpbacked dolphin, due to a lack of research.

Underwater World should conduct research on these dolphins in their natural habitats.

I am appealing to the marine park to reconsider its captive-breeding programme.

Resources could be put to better use on protection, research and rehabilitation of these dolphins, so as to reintroduce them into the wild.

SITI MARYAM YAAKUB