Contact: Shannon Lyday (808) 725-5905
May 2, 2016
Hawaiian Islands Humpback Whale National Marine Sanctuary reports lower whale sightings during 2015-2016 season
Humpback whale sightings appear to have been lower in many areas of the Main Hawaiian Islands during the 2015-2016 whale season, according to anecdotal observations by scientists and volunteers at Hawaiian Islands Humpback Whale National Marine Sanctuary. Whale researchers and tour operators around the state report similar observations.
However, due to the absence of systematic population monitoring, more information is needed to draw firm conclusions.
“A more robust and comprehensive survey throughout the Main Hawaiian Islands is needed to determine the actual numbers of humpback whales that migrate here each season to mate and give birth, how long they stay, and what waters they use,” said Ed Lyman, resource protection specialist. “Additionally, it is also important that we have a better understanding of humpback whale habitat use in other breeding areas and within the feeding areas for North Pacific humpback whales during the winter and spring months.”
The sanctuary’s Ocean Count program uses volunteers on Oʻahu, Kauaʻi, and Hawaiʻi islands to conduct shoreline observations of humpback whales on one day each January, February, and March during peak whale season. Although the information provides a snapshot of those whales seen from the coast on the three days and has limitations, the whale sightings reported this season were one of the lowest over the past five seasons. Pacific Whale Foundation conducts a Whale Count program on Maui and reported similar results.
Additionally, the sanctuary received very low numbers of reports of whales in distress. The sanctuary works with partners to track and respond to entangled or otherwise distressed humpback whales.
During the 2015-16 whale season, the sanctuary only received five confirmed reports of different whales entangled in gear. The previous two seasons resulted in 13 different whales each season being reported with confirmed entanglements. The lower numbers of reports may be due to fewer animals in the area or a reduced number of entangled whales, said Ed Lyman, resource protection specialist.
Although these reported observations and indicators suggest lower numbers, the sanctuary is not yet concerned that the North Pacific population of humpback whales is in sudden decline or necessarily affected by a new threat. The number of humpback whales in the North Pacific is estimated to be more than 20,000 animals – many experts believe this represents a healthy population.
Humpback whale numbers in Hawaiʻi are influenced by many factors including their arrival times, residency, and distribution. Humpback whales are resilient and generalist feeders, allowing them to adapt to changing environmental conditions. Additionally, changes in migration and breeding dynamics in a growing population of humpback whales may be due to the population approaching carrying capacity, or the maximum number of species that an environment can support.
It is also possible that fewer animals made the migration to their wintering grounds in Hawaiʻi. Potential factors that may have contributed to lower sightings this season could include environmental factors, such as temperature changes related to El Niño, or food resource changes on their feeding grounds in Alaska.
Another possibility is that the whales arrived in similar numbers to past years, but were not sighted within locations and timing of surveys. The sanctuary will continue to monitor humpback whales and is looking forward to working with partners to further investigate the distribution, abundance and dynamics of North Pacific humpback whales in Hawaiʻi.