Report 278
Marine mammal observations during seismic surveys in 1997
(1998)
Stone, C.J.
Observations of cetaceans seen during seismic surveys carried out in accordance with the Guidelines for minimising acoustic dusturbance to small cetaceans were forwarded to JNCC. This report presents an analysis of the data gathered.

Summary


As part of the UK's response to the Agreement on the Conservation of Small Cetaceans in the Baltic and North Seas (ASCOBANS), in February 1995 the then Department of the Environment issued the Guidelines for minimising acoustic disturbance to small cetaceans, which aimed to minimise disturbance to cetaceans from seismic surveys (a revised version of the guidelines is included in Appendix 1).  The airguns used during seismic surveys generate sound that is mostly of low frequency, overlapping with the frequencies produced by baleen whales.  These animals are therefore considered to be vulnerable to disturbance from seismic surveys (e.g. Moscrop & Simmonds 1994 and references therein).  Although toothed whales and dolphins use higher frequency sound for communication and echolocation, there is some evidence that they may also be vulnerable to disturbance from seismic surveys (Goold 1996; Stone 1996, 1997a,b).
 

The guidelines were revised by the Joint Nature Conservation Committee (JNCC) in early 1996.  Under the version of the guidelines which has been operative since 1996, operators are required to consult the Joint Nature Conservation Committee when planning seismic surveys in the UK and, if necessary, discuss precautions which can be taken to reduce disturbance.  When conducting a survey, operators are required to check for the presence of cetaceans before starting a survey line, and delay the start of the survey by at least 20 minutes if cetaceans are within 500 m.  Whenever possible, a soft-start procedure should be employed, gradually building up the airgun power over 20 minutes from a low energy starting level; in addition, the lowest practicable energy levels should be used throughout the survey.  Operators are also required to send a report of the implementation of the guidelines to JNCC after the survey.  Details of the time spent watching for cetaceans and any sightings that occurred are recorded by on-board observers using standard forms designed by JNCC (Appendix 2).  The results of an analysis of the data recorded during 1997 are presented here.

 

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ISSN 0963 8091
 
Please cite as: Stone, C.J., (1998), Marine mammal observations during seismic surveys in 1997, JNCC Report 278, ISSN 0963 8091