The New Zealand Government’s Department of Conservation (DOC) has developed the ‘2013 code of conduct for minimising acoustic disturbance to marine mammals from seismic survey operations’ (DOC 2013), known as the Code. The Code is available for any organisation carrying out seismic operations in New Zealand continental waters. The Code can be downloaded from the following link: www.doc.govt.nz/conservation/marine-and-coastal/seismic-surveys-code-of-conduct/
BASICS OF THE NEW ZEALAND SEISMIC ‘CODE’
Before the acoustic source (i.e. seismic air guns) is activated, a pre-start observation or ‘watch’ is required. This involves Marine Mammal Observers (MMOs) conducting visual observations and/or a Passive Acoustic Monitoring (PAM) Operator listening for marine mammals within relevant mitigation zones. Mitigation zones must be clear of marine mammals (other than New Zealand fur seals (Arctocephalus forsteri)) for 30 minutes and of fur seals for 10 minutes. If a marine mammal is seen within the relevant mitigation zone, there is a delay in starting the source. Once the source has been activated, the Code calls for the source to be shut down if a species of concern (www.speciesofconcern.co.nz) is seen in its relevant mitigation zone. The source is delayed or reactivated if the animal is seen to move outside its relevant mitigation zone, or 30 minutes has elapsed since the last detection, 10 minutes for New Zealand fur seals.
A soft start procedure is also required. This means that each time the source is activated, its power must be increased gradually (i.e. start with the lowest capacity air gun and gradually add successively higher capacity air guns). The soft start procedure must be carried out over a period of 20–40 minutes. The exception to this is when there is a break in full power firing for less than 10 minutes, and no marine mammals have been seen in the mitigation zones. In this case, the source can be reactivated at full power. Other exceptions may exist when conducting a low powered test (i.e. seismic source tests with a maximum combined source capacity of < 2.49 litres or 150 cubic inches, do not require a soft start).
A flowchart below shows the steps of the entire mitigation process.
For further information on observer deployment, crew observations, acoustic source tests, multiple acoustic sources, and line turns, please refer to section 3.8 Operational requirements, of the Code.
NEW ZEALAND SEISMIC GUIDELINES
While the basics of the code are similar to many other guidelines worldwide (e.g. Gulf of México – www.protectedspeciesobservation.co.uk), there are also some slight and major differences.
Before conducting seismic surveys, operators should be aware of the notification, pre-survey planning, and Marine Mammal Impact Assessment (MMIA) process required. More information on MMIAs can be found at: www.marinemammalimpactassessment.co.nz
The Code has slightly different mitigation procedures based on the level of acoustic source output. For example, under the Code there are additional requirements for starting the acoustic source of level 1 surveys in a new location in poor sighting conditions. The levels are:
- Level 1: an operational acoustic source capacity of >427 cubic inches. These tend to be large-scale geophysical investigations (often oil & gas). For more details please see www.nzlevel1seismicsurveys.co.nz;
- Level 2: 151–426 cubic inches. Lower scale investigations (often scientific). For more details please see www.nzlevel2seismicsurveys.co.nz; and,
- Level 3: <150 cubic inches. Small scale survey technologies. Not subject to provisions of the Code.
The Code includes traditional streamer seismic surveys, as well as borehole seismic surveying (check-shot and all types of Vertical Seismic Profile (VSP) surveying), which are classified into the same operational capacity levels.
Unlike any other guidelines worldwide, the Code also has varying mitigation procedures for different classifications of marine mammals. The categories are: species of concern with calf/calves, species of concern, other marine mammals, and New Zealand fur seals. A full list of the species of concern can be found at www.speciesofconcern.co.nz. For each survey level the size of the mitigation zone varies for the different categories of marine mammal. There is also no shutdown procedure required for ‘other marine mammals’, and the mitigation zone only needs to be clear of New Zealand fur seals for 10 minutes, instead of the 30 minutes for other species.
A full list of MMO and PAM Operator duties are available in the Code and its accompanying reference document (DOC 2012).
This site gives only summary of marine mammal mitigation techniques used in the New Zealand seismic survey guidelines; please see the DOC website for official documents: www.doc.govt.nz