Research Document - 2009/048

Factors influencing the Effectiveness of Marine Mammal Observers on Seismic Vessels, with examples from the Canadian Beaufort Sea

By L.A. Harwood and A. Joynt

Abstract

The Statement of Canadian Practice (SOCP) with Respect to the Mitigation of Seismic Sound in the Marine Environment requires a qualified Marine Mammal Observer (MMO) be on board a seismic vessel to verify that the safety zone (SZ) is clear for at least 30 minutes before the seismic air source array(s) is activated. A MMO is an individual trained to identify and document different species of marine mammals that are expected to be present in the area where a marine seismic survey will take place. Visual monitoring of the SZ and adjacent waters by MMOs is intended to establish and, when visual conditions allow, maintain a zone around the sound source and seismic vessel that is clear of marine mammals and sea turtles, thereby reducing or eliminating the potential for injury. The effectiveness of MMO mitigation is influenced by a number of environmental factors, including amount of daylight, sea state, swell height and visibility (fog, rain, glare, snow). In the Canadian Beaufort Sea, one or more of the factors described above could reduce the effectiveness of MMO mitigation, in approximately these proportions: 25-60% MMO down-time due to darkness, 25-40% down-time due to sea states/swell height, and 10% down-time due to poor visibility associated with fog. An assessment of the coincidence of these factors over the course of a seismic season(s) has not yet been attempted. There is a paucity of literature on the effectiveness of MMO mitigation with regard to such topics as (1) observer fatigue, (2) shift/watch duration, (3) effectiveness of single vs. multiple MMOs, (4) the height on the vantage point, and (5) the amount and type of training that is required. Examples from other jurisdictions are helpful, and include recommendations for two to three MMOs on an active seismic ship (with shifts), vantage points as high as possible and practical, that MMOs position themselves to afford 360° view of the sea surface, that shifts do not exceed four hours, and that recommended optical equipment be used. Standardization of MMO requirements is needed, although even this would not ensure that MMOs have the necessary skills, experience or communication skills to be most effective. Minimum training, standardized forms and competency standards are also required. The benefit of the continued involvement of Aboriginal observers cannot be overstated.

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