Research Confirms Importance of Northwestern Hawaiian Islands as Wintering Habitat for Humpback Whales

The primary wintering grounds of the humpback whale in the North Pacific are in the main Hawaiian Islands (MHI). In 2007, Dave Johnston, then an employee of the University of Hawaii Joint Institute for Marine and Atmospheric Research working in the PIFSC Protected Species Division, led a cetacean survey in the Northwestern Hawaiian Islands (NWHI) using visual sighting protocols and towed-array acoustics. Based on sightings, observations of whale behavior and song recordings, Johnston and his collaborators suggested that this region is also a wintering ground for humpback whales and used a spatial habitat model to estimate the potential winter habitat for humpback whales in the NWHI. Their work was published in Endangered Species Research.

Humpback whales are commonly seen in waters off the main Hawaiian Islands during their winter breeding 
                 season.  Recent research has confirmed that the whales also winter in waters of the Northwestern 
                 Hawaiian Islands.
Humpback whales are commonly seen in waters off the main Hawaiian Islands during their winter breeding season. Recent research has confirmed that the whales also winter in waters of the Northwestern Hawaiian Islands.

Recent research by Hawaii Institute of Marine Biology (HIMB) scientist Marc Lammers and colleagues found that humpback whales are common in the NWHI during winter months and confirmed that this region is an important wintering habitat for the population. To better understand the occurrence of humpback whales in the NWHI, Lammers and his collaborators deployed ecological acoustic recorders (EARs) at nine sites throughout the Hawaiian Archipelago to record the occurrence of humpback whale song, an indicator of winter breeding activity. The EAR is a microprocessor-based autonomous recorder that samples the ambient sound field on a programmable duty cycle. EARs have typically been deployed and retrieved during Pacific Reef Assessment and Monitoring Program cruises by NOAA vessels funded primarily by the NOAA Coral Reef Conservation Program. Lammers’ research is part of a collaboration between the PIFSC Coral Reef Ecosystem Division, HIMB and the Papahānaumokuākea Marine National Monument.

The timing and abundance of song recorded at each EAR site indicates that humpback whales were common in the NWHI from late December to mid-May, closely following trends observed at Oahu in the MHI and strongly suggesting that the whales use the NWHI as a wintering area. The findings of Lammers and colleagues were published in the February 10 issue of Marine Ecology Progress Series. They are particularly relevant in light of recent suggestions, based on photo-identification data, that a yet undocumented wintering area exists somewhere in the central North Pacific. The NWHI could be that area.