Investigations on Cetacea (1974)


A pilot study has been carried out in order to obtain information on the observational problems encountered in studying the harbour porpoise (Phocoena phocoena) in the wild. It is concluded that techniques other than the traditional use of field glasses are called for, for instance underwater television. However, such methods also have their limitations owing to the unstable visibility of the water and the far-ranging movements of the animals.
The vocal aspects of the porpoise’s behaviour should also be investigated as sound signals could explain the absence of visible nurturant behaviour on the part of a female towards her young.
During the study about six animals were seen, and these included a female with her offspring. This pair periodically visited the area just below the observer’s position while the others kept further out, mostly single or in pairs. On a few occasions, we witnessed meetings between the animals. These were accompanied by rather specific reactions like fast-swimming in circles and leaping. The lone animals exhibited an astonishing ability to disappear, e.g. from the middle of the observation area in perfectly calm water. Sometimes the animals were seen resting on the surface for 5-10 seconds.