Abstract

Dolphins and porpoises spend the majority of their lives underwater, out of the view of human observers. Consequently, scientists have relied on indirect means to study the foraging ecology of these animals. These indirect methods, such as examining the stomach contents of carcasses, provide an incomplete and often biased view of their feeding ecology. Promising new technological developments with data loggers and satellite telemetry are beginning to offer alternative methods to studying the foraging ecology of small cetaceans. Data loggers have long been used with other marine vertebrates but have not been suitable for dolphins or porpoises because the devices must be retrieved to recover stored data. Recent advances in their recovery have overcome some of these difficulties and loggers have now been successfully deployed on several species of small cetaceans. A new generation of small satellite-linked transmitters has allowed researchers to follow the movements and diving behaviour of animals from their offices. Continuing developments in these fields will afford new opportunities to study the lives of dolphins and porpoises and better understand how they find and obtain food at sea.