Feeling peppy with melon-headed whales off Guam

By Marie Hill, Adam Ü, Allan Ligon, and Tom Ninke

Melon-headed whales, affectionately called Peps because of their Latin name Peponocephala electra, were seen during the Pacific Islands Fisheries Science Center’s Cetacean Research Program small-boat surveys off Guam (May 6-14, 2017).  We encountered a group of over 300 whales just south of Facpi Point on the southwest side of the island.

Melon-headed whales encountered near Guam. Photo: NOAA Fisheries/Adam Ü

Peps are sometimes mistaken for pygmy killer whales because of their body size and color. Although there are some subtle differences in body color and shape, group size is usually a pretty good indicator of species.  We typically see Peps in groups of 100 or more individuals, whereas pygmy killer whales occur in groups of 50 or fewer.

Melon-headed whale spy-hopping off Guam. Photo: NOAA Fisheries/Marie Hill

The last time that we saw Peps off Guam was in April 2014.  We will be able to use the photo-identification images we took during both sightings to learn if any of the 2014 whales were present this year.  During this year’s encounter, we collected 12 biopsy samples to use for genetic analyses and deployed two satellite tags to study the movements of individuals. We have received transmissions from one of the satellite tags.  The most recent transmission was from May 13 when the tagged whale was off of Galvez Banks (southwest of Guam).

Melon-headed whale sighting location (white dot) off Facpi Point, Guam. The red line shows the satellite-tracked movements of a whale that was tagged during the sighting.

Check out the video of some underwater footage that we took during the encounter, which shows how closely associated these highly social whales live their lives.

Yes, that is indeed Pep poo at the 0:11 mark.


All survey operations including satellite tagging, photo-identification, and biopsy sampling were conducted under NMFS permit. Funding was provided by NOAA Fisheries and the U.S. Navy Commander, U.S. Pacific Fleet. We would like to thank the owner and captains of Ten27, the Guam NOAA Fisheries field office, and all of our volunteers during the surveys.


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