Het ontdekken en herkennen van Bruinvissen Phocoena phocoena op zee

Tile Harbour Porpoise probably is the commonest cetacean in Dutch (coastal) waters. However, there has been a serious decline since the second world war and at present the Harbour Porpoise is seldom seen from coastal sites. Since 1987 a growing number of birdwatchers is participating in a ship-based offshore project, and many more encouters with cetaceans are now expected. Unfortunately, very few of those participating are skilled ’whale-watchers’ and so many cetaceans will remain unidentified or, even worse, will be mis-identified. Harbour Porpoises are easily over-looked and the main aim of this paper is to point out how to detect and identify them. A description is given of the most important field-characters (blunt head, small size, coloration, small triangular dorsal fin), flock size and behaviour, its typical way of swimming, either disturbed (porpoises are afraid for motorvessels approaching or at least don’t like to come too close) or undisturbed is described and illustrated (figures 2-4). It is pointed out where to look and how to find them from a ship and what features the observer should look out for. Explained are the way of counting cetaceans (giving a minimum estimate), how to find immatures (figure 5) and what should be noted. The use of standard recording forms is recommended. Finally, a list is given of useful photo’s being published.