CSA Ocean Sciences Inc., Okeechobee, FL, United States of America.
PLoS One. 2024 Mar 21;19(3):e0300658. doi: 10.1371/journal.pone.0300658. eCollection 2024.
Visual observation data collected by protected species observers (PSOs) is required per regulations stipulated in Notices to Lessees (NTLs) and geophysical survey Permits (Form BOEM-0328) issued to seismic operators in the Gulf of Mexico (GOM). Here, data collected by certified and trained PSOs during seismic surveys conducted between 2002-2015 were compiled and analyzed to assess utility in assessing marine mammal responses to seismic noise and effectiveness of required mitigation measures. A total of 3,886 agency-required bi-weekly PSO Effort and Sightings reports were analyzed comprising 598,319 hours of PSO visual effort and 15,117 visual sighting records of marine mammals. The observed closest point of approach (CPA) distance was statistically compared across five species groupings for four airgun activity levels (full, minimum source, ramp up, silent). Whale and dolphin detections were significantly farther from airgun array locations during full power operations versus silence, indicating some avoidance response to full-power operations. Dolphin CPA distances were also significantly farther from airguns operating at minimum source than silence. Blackfish were observed significantly farther from the airgun array during ramp up versus both full and minimum source activities. Blackfish were observed significantly closer to the airgun array during silent activities versus at full, minimum source, and ramp up activities. Beaked whales had the largest mean CPA for detection distance compared to all other species groups. Detection distances for beaked whales were not significantly differences between full and silent operations; however, the sample size was very low. Overall results are consistent with other studies indicating that marine mammals may avoid exposure to airgun sounds based on observed distance from the seismic source during specified source activities. There was geographic variability in sighting rates associated with specific areas of interest within the GOM. This study demonstrates that agency required PSO reports provide a robust and useful data set applicable to impact assessments; management, policy and regulatory decision making; and qualitative input for regional scientific, stock assessment and abundance studies. However, several improvements in content and consistency would facilitate finer-scale analysis of some topics (e.g., effort associated with specific activities, observer biases, sound field estimation) and support statistical comparisons that could provide further insight into marine mammal responses and mitigation efficacy.
受法规要求，在墨西哥湾（GOM）向地震作业者发放的租船人通知（NTLs）和地球物理调查许可证（BOEM-0328 表格）中，需要保护物种观察员（PSO）收集视觉观测数据。在这里，对 2002-2015 年间进行的地震调查中经认证和培训的 PSO 收集的数据进行了编译和分析，以评估其在评估海洋哺乳动物对地震噪声的反应和评估所需缓解措施的有效性方面的效用。总共分析了 3886 份机构要求的每两周一次的 PSO 工作量和目击报告，其中包括 598319 小时的 PSO 视觉工作量和 15117 次海洋哺乳动物的视觉目击记录。对五个物种组别的最接近接近点（CPA）距离进行了统计学比较，这五个物种组别的空气枪活动水平分别为全功率、最小声源、升压、静音。与静音相比，鲸鱼和海豚在全功率作业时的检测距离明显更远，这表明它们对全功率作业有一定的回避反应。海豚的 CPA 距离也明显大于最小声源时的静音。与全功率和最小声源活动相比，在升压阶段，黑鲷鱼被观察到距离空气枪阵列更远。在静音活动期间，黑鲷鱼被观察到比全功率、最小声源和升压活动更接近空气枪阵列。与其他所有物种组相比，喙鲸的平均 CPA 最大，用于检测距离。喙鲸在全功率和静音操作之间的检测距离没有显著差异；然而，样本量非常低。总体结果与其他研究一致，表明海洋哺乳动物可能会根据指定声源活动期间与地震源的距离来避免接触空气枪声音。在 GOM 的特定感兴趣区域与目击率存在地理差异。这项研究表明，机构要求的 PSO 报告提供了一个强大而有用的数据集，适用于影响评估；管理、政策和监管决策；以及区域科学、种群评估和丰度研究的定性投入。然而，在内容和一致性方面的一些改进将有助于更精细地分析某些主题（例如，与特定活动相关的工作量、观察员偏见、声场估计），并支持统计比较，这可以进一步深入了解海洋哺乳动物的反应和缓解效果。
