Data from: Year-round spatiotemporal distribution of harbour porpoises within and around the Maryland wind energy area

Offshore windfarms provide renewable energy, but activities during the construction phase can affect marine mammals. To understand how the construction of an offshore windfarm in the Maryland Wind Energy Area (WEA) off Maryland, USA, might impact harbour porpoises (Phocoena phocoena), it is essential to determine their poorly understood year-round distribution. Although habitat-based models can help predict the occurrence of species in areas with limited or no sampling, they require validation to determine the accuracy of the predictions. Incorporating more than 18 months of harbour porpoise detection data from passive acoustic monitoring, generalized auto-regressive moving average and generalized additive models were used to investigate harbour porpoise occurrence within and around the Maryland WEA in relation to temporal and environmental variables. Acoustic detection metrics were compared to habitat-based density estimates derived from aerial and boat-based sightings to validate the model predictions. Harbour porpoises occurred significantly more frequently during January to May, and foraged significantly more often in the evenings to early mornings at sites within and outside the Maryland WEA. Harbour porpoise occurrence peaked at sea surface temperatures of 5°C and chlorophyll a concentrations of 4.5 to 7.4 mg m-3. The acoustic detections were significantly correlated with the predicted densities, except at the most inshore site. This study provides insight into previously unknown fine-scale spatial and temporal patterns in distribution of harbour porpoises offshore of Maryland. The results can be used to help inform future monitoring and mitigate the impacts of windfarm construction and other human activities.

海上风电场可提供可再生能源，但施工阶段的作业活动可能会对海洋哺乳动物造成影响。为明确美国马里兰海域海上风能区（Maryland Wind Energy Area, WEA）内一座海上风电场的施工会如何对港湾鼠海豚（Phocoena phocoena）产生影响，首先需探明其鲜为人知的全年分布情况。尽管基于栖息地的模型可辅助预测采样受限或无采样区域的物种出现概率，但仍需通过验证以确定预测结果的准确性。本研究整合了超过18个月的被动声学监测（passive acoustic monitoring）港湾鼠海豚检测数据，采用广义自回归移动平均模型与广义可加模型，探究马里兰海上风能区内外港湾鼠海豚的出现情况与时间及环境变量的关联。研究将声学检测指标与通过航空及船舶目击数据推导得到的栖息地密度估计值进行对比，以验证模型预测结果。在马里兰海上风能区内外的监测点中，港湾鼠海豚的出现频次在1月至5月显著更高，且其觅食活动多集中在傍晚至清晨时段。当海表温度为5℃、叶绿素a浓度处于4.5~7.4 mg·m⁻³区间时，港湾鼠海豚的出现频次达到峰值。除最靠近近岸的监测点外，声学检测结果与模型预测的种群密度均呈显著相关关系。本研究揭示了马里兰近岸海域港湾鼠海豚分布此前未被探明的精细时空分布模式，其结果可为未来的监测工作提供参考，并有助于减轻海上风电场施工及其他人类活动带来的生态影响。