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Workshop Takes Place To Further Understanding Of Seismic Impact On Marine Mammals

Thursday 2 July 1998

Workshop Takes Place To Further Understanding Of Seismic Impact On Marine Mammals

Representatives from offshore oil companies, geophysical contractors, environmental regulators and non-governmental organisations, along with marine biologists, academics and bio-accoustic specialists came together last week (23-25 June) to discuss the impact of seismic operations on marine mammals.

Organised jointly by the Atlantic Margin Joint Industry Group (AMJIG) - a body representing oil companies operating offshore to the west of Britain, the International Association of Geophysical Contractors (IAGC), the Joint Nature Conservation Committee (JNCC), NERCs Sea Mammal Research Unit (SMRU) and the International Fund for Animal Welfare (IFAW), the Seismic and Marine Mammals Workshop attracted almost 100 delegates from across Europe and as far afield as the Far East and the United States.

Its purpose was to develop common understanding amongst participants of the interaction between seismic operations and marine mammals. In a series of papers, workgroups and discussions, the three day session aimed to:

* review existing research and current areas of concern

* identify gaps in knowledge * consider future research needs and the direction of regulatory trends

Although oil companies have explored the Atlantic Margin area for more than 20 years, increased levels of activity in recent years have led to concerns amongst regulators, NGOs and the general public about the potential impact of these operations - and seismic activity in particular - on marine mammals. This workshop has, for the first time in the UK, brought the relevant experts together and, in pooling knowledge, have helped identify areas for future improvements.

The workshop made a number of recommendations which will be published in the final papers later this year.

Note to Editors:

* Seismic surveying techniques underpin oil exploration and production, allowing scientists to build up images of rock formations below the seabed and help pinpoint potential oil reserves.

* In general terms, seismic surveying equipment works on the same principle as radar or sonar devices. Pulses of low-frequency sound are released at regular intervals, which pass through the water and the seabed to be reflected by the geological layers beneath the surface of the earth. The reflected echoes are recorded and analysed, and the results are used to create a computer-generated image of the geology far below the bottom of the sea.

* Survey engineers use an array of underwater airguns towed behind the survey ship to release a pop of compressed air. These brief pulses occur approximately every ten seconds. The echoes coming back from the subsurface rock formations are measured by a towed array of cables fitted with hydrophone sound detectors while the survey vessel sails along a pre-determined line several kilometres long.


* Seismic practice

Overview of seismic methodology, history of technique and future trends, licensing and permitting, activity by area - historical trends and current outlook, operational constraints including the effects of seismic interference.

* Physics of sound in water

Fundamentals and meaning of measurements, propagation/attenuation of sound in water, effect of water depth and sea bottom coupling, comparisons between different types of air guns and alternative sources.

* Biology of marine mammals of the north-east Atlantic (in relation to seismic energy)

Types of marine mammals encountered, sensitivity of hearing to frequency and source energy levels, behaviour, geographical distribution and seasonal occurrence, migration paths/patterns, population level and conservation status.

* Seismic and marine mammal interaction

Overview of the effects of sound and how this is measured/assessed, interaction with prey species - possible changes in food stock distribution, evidence for hearing damage including comparison with the effects on humans, behavioural responses - long term effects, relevant international studies - past and present.

* World-wide review of mitigation of (potential) effects

Legislative requirement, guidelines and restrictions world-wide, conceptual framework for current approach, criteria by which current practices were arrived at, on-going studies and future directions.

For more information, please call 020 7802 2400.