Shore and Vessel-Based Surveys

a researcher conducting a shore-based survey of whales

The abundance of whales in the Hawaiian Islands fluctuates from year to year and the sanctuary takes a leading role in evaluating these trends. Sanctuary researchers and partners conduct acoustic monitoring efforts to estimate whale presence based on the singing activity of males. However, it is not clear how well these results reflect trends in the population overall, which can include non-singing males, females, and calves. The sanctuary conducts both shore-based and vessel-based surveys each winter to further enumerate whale abundance in the Maui region and to correlate visual counts with recorded levels of singing.

Researchers conduct weekly shore-based surveys to record the position of whales from an elevated observation station off Olowalu, Maui. They perform 30-minute scans throughout the day using surveying equipment to log the distribution and the number of whales in the west Maui area.

In addition, sanctuary scientists conduct bi-weekly vessel surveys in the same area off west Maui using the sanctuary’s R/V Koholā. They log the parameters of whale sightings (bearing, distance, number of whales, etc.)and then use this information to calculate an estimate of whale density for the study area. Both types of survey data are combined to establish trends in whale abundance off west Maui both in and between seasons.