Thank you for your letter of 24 March about the sperm whale that was recently stranded in the Firth of Forth and seismic testing in the area west of Shetland.

Seismic activity has been undertaken in this area since the early 1970's and then only in the summer months because of prevailing weather conditions. The last recorded activity in the UK Atlantic Margin took place in September 1996. However, increased numbers of sperm whales have been seen in the North Sea in the last five years and yet seismic activity continues all year round in that area.

Records of sperm whale strandings go back to the year 850 and there is evidence that these beachings occur in cycles, with long periods of time between them. I understand that it is likely that we are now in one of those cycles, with several beaching incidents reported over the past few years.

The oil and gas industry has been involved with the development and use of guidelines for reducing any potential disturbance to cetaceans from seismic surveys. Companies consult with the Joint Nature Conservation Committee (JNCC) on the optimal times of year to carry out surveys and Masters of the support vessels have been trained to carry out monitoring of cetaceans around the vicinity of the surveys. These guidelines include delaying initiation of the survey if any are found within 500m of the vessel containing the equipment. Some companies are also helping to develop acoustic hydrophones which can be carried on support vessels to identify cetaceans close to the operations. This should further help minimise the disturbance seismic operations may cause.

Although it is always distressing to see these animals stranded, I believe that there is no evidence to link this particular case with the development of the Atlantic Margin oilfields.