Spatial Capture-recapture of Kauaʻi Pilot Whales

Pilot whales in Hawaiʻi form distinct island-associated communities that may be sensitive to localized threats. This project uses photo-identification and spatial capture-recapture to refine abundance estimates and support NOAA stock assessments.

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Background

Current abundance estimates for short-finned pilot whales (Globicephala macrorhynchus) in Hawaiʻi group all individuals into a single population. However, photo-ID, telemetry, and genetic data show that Hawaiʻi contains both pelagic and insular populations, with the insular population further divided into island-associated communities that have limited interchange. As a result, population-wide estimates can obscure trends within these smaller, demographically independent populations. The Kauaʻi/Niʻihau community is of particular concern due to its limited range and elevated exposure to anthropogenic noise. These whales exhibit strong site fidelity and cohesive social structure, making them especially vulnerable to disturbance and slow to recover from demographic change.

To generate population-specific estimates, this project applies spatial capture-recapture models to long-term photo-identification data collected by Cascadia Research Collective from 2011 to 2023. This work produces the first spatially explicit, population-level abundance estimates for short-finned pilot whales around Kauaʻi and Niʻihau, providing a foundation for monitoring localized trends and demonstrating how non-systematic survey datasets can meaningfully inform marine mammal management and conservation.