Hawaiian Pilot Whales Exhibit Surprising Squid Diet and Hunting Behavior

New research reveals that Hawaiian short-finned pilot whales, or Globicephala macrorhynchus, have a surprisingly massive diet consisting mainly of squid. According to a study published in the Journal of Experimental Biology, these whales consume between 82 and 202 squid daily, amounting to an estimated annual intake of about 88,000 tonnes of squid for the entire population.

This study, conducted by a collaborative team from the USA, Spain, Australia, and Denmark, aims to assess the sustainability of whale populations and their food sources in Hawaiian waters. Researchers utilized suction-cup tags on eight pilot whales to gather crucial data, including motion patterns, video footage, and echolocation audio.

William Gough from the University of Hawaii at Manoa explained that the tags captured vital information during the whales' deep dives. They documented 118 deep dives, with whales reaching depths of up to 864 meters and averaging around 39 dives per day.

Analyzing the energy expenditure during these dives revealed that whales expend 73.8 kJ per minute while diving and 44.4 kJ per minute at the surface. To meet their energy needs, the study concludes that each whale must consume approximately 73,730 squid per year.

The researchers also calculated that an average of about four squid are captured per dive, with each squid providing roughly 560 kJ of energy. Scaling these findings to the larger population, they estimate that up to 8,000 short-finned pilot whales inhabit Hawaiian waters, capable of consuming substantial amounts of squid without threatening local squid populations.

This research highlights a healthy food supply for the whales, suggesting they are in relatively good condition in Hawaii. Gough expresses optimism about the species' future in this region, noting the abundance and reliability of their food source.

The findings underscore the importance of understanding the dietary habits and hunting behaviors of these whales for conservation efforts and marine ecosystem management.