IMIS

The primary objectives of the NEFSC Marine Mammal Abundance Cruise 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. During the NEFSC Marine Mammal Abundance Cruise 2004, no detections of harbor porpoise were made, although automated detections of echolocating dolphin species were made as groups passed directly by the hydrophone. A single porpoise-like event was attributed to a sighting of Kogia simus. The Porpoise detector was developed by Douglas Gillespie and Olly Chapple for the International Fund Welfare (IFAW). It uses analog envelope tracing and software detectors; two narrow bandpass filters centered around 50 and 72 kHz and one broadband filter (100 kHz - 150 kHz). These are used to detect the broadband click ultrasonic vocalizations of dolphins, and the narrow band clicks produced by the harbor porpoise (Phoceona phocena), Vaquita (Phocena sinus) and Kogia spp. The detector was extensively trialled in the Baltic (Gillespie et al. 2005; OBIS-SEAMAP dataset: Baltic Porpoise Acoustic Surveys 01-02) and upper Gulf of California. [Gillespie, D., P. Berggren, S. Brown, I. Kuklik, C. Lacey, T. Lewis, J. Matthews, R. Mclanaghan, A. Moscrop and N. Tregenza. 2005. Relative abundance of harbour porpoises (Phocoena phocoena). Journal of Cetacean Research and Management: 7(1):51-57.] Additional attributes caveat: 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.