Dolphins are part of our natural heritage, and we should do our utmost to protect them and remove all hazards that threaten their survival (Dolphin caught in fishing line at Bedok Jetty; April 8).

A comprehensive survey should be carried out to determine the population of wild dolphins in our waters, if that has not already been done. Perhaps tagging some of these dolphins with Global Positioning System devices could help us find out more about their feeding and breeding grounds.

Wild dolphins, sharks and other sea creatures used to be seen frequently in our waters in the past. But they are a rare sight now.

Surveys of anglers fishing in permitted areas such as Bedok Jetty could be carried out to help gather data on our fish stocks.

This would enable the authorities to monitor our marine ecosystem and take steps to protect it.

Lee Kay Yan (Miss)