Statement of Canadian Practice with respect to the Mitigation of Seismic Sound in the Marine Environment

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• Introduction
• Background Paper
• Context
• Definitions
• Application
• Poster

Poster

Statement of Canadian Practice with respect to the Mitigation of Seismic Sound in the Marine Environment

MARINE SEISMIC SURVEYS IN CANADA are conducted in the Atlantic, Pacific and Arctic oceans in waters with very diverse biological, oceanographic and geomorphic characteristics. In response to public concerns over the potential impacts of seismic surveys on marine life, federal and provincial authorities responsible for the review and assessments of proposed surveys agreed to develop a national code of conduct.

DEVELOPMENT PROCESS

1. National and international peers reviewed scientific evidence of potential physical, physiological and behavioural impacts associated with seismic survey, considering the direct, indirect, chronic or cumulative nature of those impacts.
2. Technical experts reviewed and identified best mitigation practices used world wide.
3. Public review of the draft Statement was completed.

OUTCOME

Conclusions were drawn using a risk-based approach that considered the likelihood of occurrence, the frequency and duration of the mitigated impact, the recovery potential and the ecological significance or severity of the impact.

THE STATEMENT DOES NOT APPLY TO ICE COVERED WATERS, TO NON-ESTUARINE PORTIONS OF RIVERS OR TO LAKES.

During the Planning Phase the Statement sets out mitigation requirements that must be met:

EXERCISING PRECAUTION, operators must minimize the unnecessary introduction of sound and design survey which:

• use the minimum energy needed.
• reduce horizontal spread.
• reduce the generation of unnecessary high frequency sounds.

The peer review process concluded that at certain received sound levels, behavioural changes could be manifested by some marine fish, marine mammals and sea turtles. The review also recognized that additional precaution was called for to address the needs of marine species listed as endangered or threatened and that individual level impacts should therefore be mitigated.

Surveys must therefore be designed to avoid causing:

• a significant adverse effect for an individual marine mammal or sea turtle listed as endangered or threatened in the Canadian legislation to protect species at risk;
• a significant adverse population-level effect for any other marine species;

REDUCING THE IMPACT ON POPULATION

To reduce the potential impacts of the survey and to reflect the peer review conclusion that population-level impacts could result if surveys were conducted in areas and at times when large groups of marine mammals and fish were engaged in critical biological activity, surveys must be planned to avoid:

• displacing an individual endangered or threatened marine mammal or sea turtle breeding, feeding or nursing;
• diverting an individual endangered or threatened marine mammal or sea turtle from a known migration corridor;

Surveys must also be planned to avoid:

• dispersing large groups (aggregations) of spawning fish from know spawning areas.
• displacing a group of breeding, feeding or nursing marine mammals, if it is known that there are no alternate areas available or if use of those areas will result in significant adverse effects.
• diverting large groups of fish or marine mammals from known migration routes if it is known that there are no alternate routes or that using those routes will result in significant adverse effects.

REGIONAL FLEXIBILITY

The diverse biological, oceanographic, geomorphic characteristics of the Atlantic, Pacific and Arctic oceans require that regional flexibility be built into the code of conduct for seismic operations. Environmental processes and the associated regulatory reviews may require additional or modified mitigation as required to address regional specificities, chronic or cumulative effects, variations in sound propagation levels, or other region or project specific conditions.

During field operations a number of mitigative measures are required during the conduct of the seismic survey.

THESE INCLUDE THE establishment and monitoring of a Safety Zone, which must at a minimum be 500m as measured from the center of the air source array.

SAFETY ZONE

The Statement recognizes that in certain circumstances, an environmental assessment process may identify the need for a safety zone greater than 500m. It further specifies that for 30 minutes prior to start up, the area must be clear of whale, dolphin, porpoise or sea turtles and that a regular watch maintained during the conduct of the survey.

Recognizing that many marine species appear to avoid seismic vessels when the air sources are active, seismic operators are required to start up the air source arrays with a pulse from the lowest energy source. The remainder of the sound sources on the array must be gradually activated over a fixed period of time.

SHUT DOWN

Survey activities must be suspended if an endangered or threatened marine mammal or sea turtle or if a marine mammal or sea turtle identified by an environmental assessment process as possibly subject to population-level impacts enters the safety zone. Air sources can be gradually ramped up when the animals have left the area.

LINE CHANGES AND MAINTENANCE

To futher reduce the amount of unnecessary sound entering the marine environment, operators are required to either shut down the energy source completely or shut down all but one source when active surveying ceases for example during line changes or for maintenance reasons.

LOW VISIBILITY

Reduced visibility due to shorten light periods, fog, storm conditions may limit the ability of the marine mammal observer to watch the full extent of the Safety zone. In situations of low visibility, the Statement calls for the use of alternate monitoring measures to detect the presence of cetaceans if the survey is in an area identified as critical habitat for an endangered or threatened vocalizing cetacean, or if the survey areas has been identified as an area where a species for which significant environmental impacts have been identified by an environmental process.

It is recognized that the field of cetacean detection technology is a rapidly evolving one and that there are limitations to the current technology particularly with respect to the location and identification of the vocal signature of the cetacean. Required use of cetacean detection technology is limited to areas where operators can expect the presence of endangered or threatened cetaceans or species for which special concerns have been identified through an environmental process. Precaution is called for and operators are directed to treat all non-identified cetacean vocalizations as those of endangered, threatened or species for which concern has been identified by the environmental process and to shut down until the area until no vocalizations have been detected for a fixed period of time.

The Statement of Practice is reviewed annually by the governments. The review allows for revisions to the requirements based upon new technologies, science findings, innovative industry practices and discussion with other government regulators.