2023, APEM, POSEIDON, Northern Isles Seabird and Marine Mammal Surveys dataset https://portal.medin.org.uk/portal/start.php?tpc=015_bf4a77ee0eac68d01f5ea5f44ba8144c This series includes the reporting and data deliverables for seasonal aerial surveys of seabirds and marine mammals east of Shetland in the Scottish Northern Isles. The surveys were completed as part of POSEIDON, a multi-year, multi-partner project funded through The Crown Estate OWEC programme and led by Natural England. The series constitutes: The first seasonal (September to October 2023) report outlining results from digital aerial surveys conducted in September 2023 within the Northern Isles under the POSEIDON project and commissioned by Natural England. Surveys were undertaken using APEM’s high-resolution camera system to capture digital still imagery of birds and marine megafauna within the Survey Area. The survey was successfully carried out across one day in September 2023. A total of 4,851 observations were recorded during the survey in September 2023, of which 4,769 were observations of birds and 82 were observations of marine megafauna 20240314 20240314