Geophysical Surveys

 


 
It is recognised that sound generated from geophysical survey sources has the potential to cause injury (e.g. hearing damage) and disturbance to marine mammals (cetaceans and seals). These surveys determine characteristics of the Earths subsurface by sending acoustic pulses into the layers beneath the sea floor and recording the time taken for each wave to bounce back. In the marine environment, they are used widely by the oil and gas, renewables and aggregate industries. 
 
Killer whale (Orca) ©Alex BrownSeismic surveys in particular have the potential to result in a deliberate injury or disturbance offence as defined under UK regulations1 to European Protected Species (EPS). These species are listed on Annex IV of the EU Habitats Directive and in the marine environment includes all cetacean species. Seismic surveys typically use an array of air-filled chambers and hydrophones which are towed behind the vessel. The air-filled chambers (known as airguns) release bursts of high pressure energy towards the sea floor and the returning sound waves are detected and recorded by the hydrophones.
 
JNCC have developed mitigation guidelines to be implemented during geophysical surveys which have been adopted as part of the consenting regime for geophysical activities within the United Kingdom Continental Shelf (UKCS) to reduce the risk of deliberate injury to marine mammals. Whilst the mitigation measures in these guidelines have some limitations and their effectiveness has not been and may not be able to be fully tested, they are based on reasonably conservative assumptions. It is considered that compliance with these guidelines constitutes best practice and will, in most cases, reduce the risk of deliberate injury to marine mammals to negligible levels. The JNCC guidelines do not deal with disturbance directly, however it is considered that the mitigation measures contained may also assist in reducing potential disturbance.
 
The guidelines were originally written with the oil and gas industry in mind, however since their conception, the use of geophysical technology by other industries in the marine environment has grown, and subsequently these guidelines are also used by other industries. They have been reviewed five times by JNCC following consultation with relevant stakeholders. In addition to these comments, the current revision also considered the 2015 review of marine mammal observer (MMO) data and compliance (Stone, 2015 a and b), new research into potential impacts to marine mammals from anthropogenic noise and new developments in geophysical and monitoring technology.
 
The guidelines advise on the use of marine mammal observers (MMOs) and Passive Acoustic Monitoring (PAM) to conduct pre-shooting searches for marine mammals, and a delay in operations should a marine mammal be detected within a specified mitigation zone. MMOs receive formal training in their role through attendance on a JNCC approved Marine Mammal Observer Courses. Discussions are currently underway to identify minimum standards for the use of PAM as a mitigation tool, including operator training requirements.
 
In addition to the current guidelines, a standardised marine mammal recording form is provided below. This is an Excel spreadsheet with embedded worksheets. In addition, a ‘Deck form’ is available which MMOs may prefer to use when observing before transferring the details to the Excel Spreadsheets. A guide to completing these forms is also provided. 
After each survey is complete, a ‘MMO report’, is submitted to the Regulator and JNCC along with the completed marine mammal recording forms. This report details how the guidelines were implemented and any problems encountered or instances of non-compliance. Data from these forms is analysed by the JNCC and a series of reports have been produced (see below).
 
The ability to determine range is a key skill for MMOs and a useful tool to assist in this function is a range finding stick. Instructions on how to design and use a range finding stick are provided below. 
 
NOTE:
1)    The 2017 guidelines were released 7 April 2017. A Frequently Asked Questions (FAQ) document providing further background to some elements of the guidelines will be published once finalised.
2)    The standardised reporting forms are being reviewed and will be published once finalised.
3)    A consultation into current MMO training requirements will be undertaken in 2017. Further information will be published once available.
4)    Discussions are currently underway to identify minimum standards for the use of PAM as a mitigation tool, including operator training requirements. Further information will be published once available.
 
 
 
 
 
[1] Regulation 41(1a) of the Conservation of Habitats and Species Regulations 2012; Regulation 39(1a) of the Conservation (Natural Habitats, &c.) Amendment (Scotland) Regulations 2012; Regulation 34(1a) of the Conservation (Natural Habitats, &c.) (Amendment) Regulations (Northern Ireland) 2015; Regulation 39(1a) of the Offshore Marine Conservation (Natural Habitats &c.) Regulations 2007 (as amended); Regulation 10(a) of the Offshore Petroleum Activities (Conservation of Habitats) Amendment Regulations 2007.