Coordinated drone surveys reveal entanglement prevalence in northeastern gray seals

Sarah Sharp described coordinated drone surveys and a tiered entanglement‑determination and health‑scoring protocol developed to estimate entanglement prevalence for gray seals in the Northwest Atlantic. Teams conducted method development surveys and multi‑site flights at several haulouts, developed a standardized rubric to score circumferential constriction and associated lesions, and tested thermal imaging as an adjunct. Outcomes showed that UAS can identify entanglement cases across different haulout substrates and that vessel‑based imagery often provides higher‑resolution confirmation of severity.

Sharp reported counts from coordinated surveys: in a September series the team counted almost 1,400 gray seals and identified 12 entangled individuals (a prevalence example reported in the meeting as ~0.86% in that survey); a June survey counted ~700 seals and identified eight entangled individuals. She noted the matrix produces conservative, minimum counts that can be improved by expanding geographic scope and integrating vessel imagery and thermal sensors. "These coordinated multi‑site surveys have been able to provide a more accurate serious‑injury estimate for the Northwest Atlantic stock," Sharp said, and recommended expanding coverage to improve stock‑level inputs for assessment reports.