New spatial mark‑recapture methods aim to refine abundance and stock structure estimates

John Durban of the New England Aquarium presented methods to apply spatial mark‑recapture frameworks to photographic mark‑recapture data for wide‑ranging, structured whale populations. He described a continuous spatial mesh approach and Bayesian MCMC implementation (using NIMBLE) that estimates latent individual activity centers and allows clusters to be interpreted as population structure or stocks. "The solution that I'm working on... is spatial mark recapture where we estimate the unobserved activity centers for each individuals," Durban said, explaining how the method can accommodate opportunistic data and environmental covariates.

Durban illustrated two case studies: eastern Bering Sea Alaska resident killer whales and west‑coast transient (mammal‑eating) killer whales. The spatial clusters identified in photographic data aligned with genetic structuring in the Alaska example, and Durban said the approach can improve survey design, incorporate citizen‑science photo contributions, and help redefine stock boundaries where evidence emerges. He urged developing computational tools that combine structured surveys and opportunistic photo‑ID datasets to produce stock‑specific abundance and demographic estimates useful for PBR calculations.