Beaked whales (Family Ziphiidae) are among the least understood cetaceans, primarily due to their deep-diving behavior and elusive nature. This has resulted in significant knowledge gaps, with most species classified as “Data Deficient” by the IUCN, despite facing significant threats from anthropogenic noise, fishing gear entanglement, and other human activities. The lack of robust population data is a primary impediment to effective conservation and management.

This project addresses this critical data gap by conducting a systematic population assessment of two species—Cuvier’s beaked whale (Ziphius cavirostris) and the Peruvian beaked whale (Mesoplodon peruvianus)—in the waters off Magdalena Bay, Baja California Sur. Using passive acoustic monitoring, we aim to generate the first reliable population estimates for these species in this ecologically significant region.

Methodology

The primary objective is to estimate the population density and abundance of the target beaked whale species. To achieve this, our research employs a standardized acoustic line-transect survey methodology.

• Acoustic Data Collection: We will tow a SoundTrap hydrophone at a consistent speed and depth across predefined transects covering the continental shelf and slope. This system is designed to record the high-frequency echolocation clicks characteristic of beaked whales.
• Data Analysis: The acoustic data will be processed to detect and classify clicks to the species level. Population estimates will be derived by incorporating several key parameters into statistical models:
  • Species-specific click detection rates per unit of effort.
  • Known vocalization characteristics of each species.
  • The effective detection range of the hydrophone system.

This quantitative approach will provide a statistically robust baseline of the regional beaked whale populations.

Conservation & Management Implications

This research is designed to produce actionable scientific data that directly informs conservation and management. Reliable population estimates are a critical prerequisite for assessing threats and designing effective mitigation strategies.

The data generated by this project will directly contribute to:

• Establishing a quantitative population baseline against which future trends and the impacts of environmental change can be measured.
• Informing risk assessments related to the impacts of naval sonar, seismic surveys, and commercial shipping noise on beaked whale populations.
• Guiding the development of evidence-based policy for marine noise regulation and the designation of potential marine protected areas or other management zones.

By filling a significant knowledge gap, this work will enhance the conservation status of these vulnerable species and provide a methodological framework that can be applied to study cryptic cetaceans in other data-poor regions.