IMIS - Marine Onderzoeksgroepen

The primary objectives of the survey were to:

1. determine the spatial distribution and abundance of cetaceans and turtles in the study region,
2. determine the spatial distribution and relative abundance of sea birds in the same region, and
3. use passive acoustics to record vocalizing cetaceans that will hopefully be used to improve the abundance estimates derived from the visual surveys.

A secondary objective was to compare the distribution of these species with each other, physical characteristics, such as depth contours and water temperature, and biological characteristics, such as relative plankton distributions. Dolphin species were detected aurally at 425 (26%) monitoring stations during Leg I and 220 (23%) during Leg II. The whistle detector (medium frequency tonal detector) detected a total of 3,340 whistle events and 273,915 whistle fragments. Long recordings of single species dolphin groups, for example common dolphin (Delphinus delphis), striped dolphin (Stenella coruleoalba) and pilot whale (Globicephala spp.), made during the course of these cruises can be used in subsequent statistical analyses to determine species-specific characteristics to improve automated species classification. Whistle is a software-based tonal sound detector developed by Douglas Gillespie for the International Fund for Animal Welfare. It was originally developed to detect tonal sounds from made by a wide range of odontocetes and also some anthropogenic noise sources. Whistle does not support species classification, background noise or other whistles mean that the whistle tracing algorithm is unable to link whistles where they overlap, thus most the detector output is a whistle fragments. Currently (2009), the latest implementation of Whistle is implemented in the PAMGUARD software. Additional attributes caveats: The ranges and bearings associated with these data have not been validated or corrected in any way so they may vary from fairly accurate to completely wrong. Counts refer to whistle detections, not animals, and the relation between these values is unknown.