Data from 420 seismic surveys conducted between 2005 and 2017 from three key areas for E&P activities, the US Gulf of Mexico, West Africa and Australia, were analysed to explore the potential effects of underwater sound from marine geophysical surveys upon marine species and compared with the findings of previous studies undertaken using similar datasets from the UK and US Gulf of Mexico. The majority of the projects, 88%, utilized a large or very large array (more than 500-cu in.; as defined by Stone (2015)). There was a total of 32,408 visual sighting events that was analysed from all combined regions. The largest volume of data was collected in the U.S. Gulf of Mexico region, with 244 seismic surveys, yielding 20,748 sighting events of approximately 124,640 animals in 30 species groups (marine mammals and sea turtles). The smallest volume of data was collected in the West Africa region, with 4518 detection events but the dataset from this area included the second largest number of animals reported, approximately 107,124 animals in 37 species groups. The largest number of species identified was in the Australia dataset; 40 species reported in 4882 sighting events. Sighting events were analysed in each of the three regions and as a combined dataset, which also included data contributed from other regions outside the three focus areas (26 project datasets containing 2224 sighting events). Species were grouped into categories for analysis with baleen whales, sperm whales, beaked whales, pinnipeds and sea turtles analysed separately, where sufficient records existed. All cetaceans were also analysed together. Generally, analysis results of sighting records in each region were consistent with the results of the combined region analysis and results were generally consistent with results of similar studies, such as the Stone (2015) report, undertaken using PSO data in the past. In both the Gulf of Mexico and West Africa where the largest dataset existed, all species groups were found to occur at greater distances from the seismic source during times of full power source operation when compared to silence. Australia PSO datasets did not include closest approach to the source so this analysis could not be undertaken in that region. In the Gulf of Mexico, where the largest dataset existed, sperm whale sighting events and delphinid sighting events were significantly shorter during full volume source operation than during source silence. A similar trend was seen in the West Africa and Australia datasets where sperm whale sighting events had a significantly shorter duration during full power operations as compared to silence. These results suggest that large whales might increase their time spent at the surface, where they are available to be sighted, when an acoustic source is active. A behavioural analysis relative to seismic source status was undertaken for all of the species groups in each region and in all regions combined. Behaviour labels / descriptions were standardized and fit into 18 defined categories. When comparing full power source operations with silence for the ‘All Cetaceans’ species group, there were statistically significant differences between the behaviours observed: bow riding, diving and logging were more prevalent when the seismic source was silent whereas blowing, breaching and surfacing were found to be more prevalent during full power activity. These trends were observed in each of the three regions to some degree. When examining the combined dataset for source ramp-up operation mode, no species group presented any significant difference in recorded behaviour as compared to any other source operating level. This report represents the longest term and most widespread geographical analysis of PSO data. As PSOs will continue to be a requirement to undertaking seismic survey activities in many areas of the world, the data collected can continue to provide an important resource for understanding how seismic activity impacts marine life. In addition, these data can be used to inform regulatory decision making with respect to development and adaptation of appropriate monitoring and mitigation regulations globally. In order to maximize the potential of PSO data, companies should be encouraged to share data in a secure, centralized location such that it is available for periodic analysis and further standardization of PSO training and data collection should be prioritized.
Link To Publication
Some links to publications are behind pay-walls and hence might not be readily accessible to the public