Digital video aerial surveys of seabirds and marine megafauna in the Gulf of Maine from May 2023 to January 2024

HiDef designed the survey using 2.5 km- and 5 km-spaced transects across the Gulf of Maine survey area, covering approximately 6,673 km². Surveys were undertaken using an aircraft equipped with four HiDef cameras with a sensor package designed and calibrated to achieve a resolution of 1.5cm Ground Sample Distance (GSD). Each camera sampled a strip of ~ 104m width, separated from the next camera by ~ 17m, to provide a combined sampled width of 416m within a 467m overall strip.

All four cameras were analyzed, achieving approximately 10% coverage of the survey area during each flight. Data analysis followed a two-stage process in which video footage was reviewed (with a 20% random sample used for audit) and detected objects were identified to species or species group level (again with 20% selected at random for audit). The audit of both stages requires 90% agreement to be achieved.

The surveys recorded a total of 7,248 birds of 33 species and 534 non-avian animals of 12 species, in addition to two dead birds. A further 409 birds and 58 non-avian animals were recorded which were not assigned to a species. An identification rate to species level of 94% was achieved throughout the survey period.