Kauaʻi’s Other Whales and Dolphins – Rare Sightings

Robin W. Baird

A mother and calf pair of melon-headed whales. Photo by Robin W. Baird/Cascadia Research.

Whale season is not over, it is just that one of the species that uses the area — humpback whales — has departed for the summer.

Last summer, during a two-week field project working in the Kaulakahi Channel and along the Kauaʻi’s South Shore, we encountered four species of whales. One of them was a group of seven Blainville’s beaked whales, which forage day and night in deeper waters around the island.

The group of Blainville’s beaked whales included three mother-calf pairs and one adult male, the latter identified by the barnacle-covered tusks that extend above the jaw, as well as by the scars from fighting with other males. This species is rarely seen in the area as they typically dive for over an hour, and can be difficult to spot except when the seas are very calm. Yet, based on acoustic detections on the Navy’s hydrophone (underwater microphone) range at Pacific Missile Range Facility (PMRF) this species is regularly in the area, and we found the group by responding to an acoustic detection by Navy researchers monitoring the hydrophones.

Our encounter with the group was only our seventh encounter with this species off Kauaʻi or Niʻihau in the 13 different years since our first project there in May/June 2003. Over the years, we’ve spent 220 days on the water off Kauaʻi and Niʻihau and have covered over 15,000 miles of survey tracks, and regularly see several species of whales outside of winter months.

A rough-toothed dolphin leaping. This species is the most common dolphin around Kauaʻi or Niʻihau, but is primarily found in deeper waters (>300 fathoms). Photo by Colin J. Cornforth/Cascadia Research.

As well as getting good identification photos of all the beaked whales, we were able to deploy two satellite tags on individuals in the group. With this and other species, we use remotely deployed satellite tags to study their movements and behavior — we use an air rifle for tagging and they anchor into the fin with titanium darts. Most of the tags we’ve deployed record and send information back on diving behavior (the depth and duration of dives), as well as GPS locations. The two tagged Blainville’s beaked whales stayed together off the northwest part of the island for at least 10 days, and we documented dives to over 4,000 feet deep during that time.

The other three “whales” encountered during the August 2021 trip were actually oceanic dolphins that are referred to as whales — short-finned pilot whales, false killer whales, and melon-headed whales.

Short-finned pilot whales are around Kauaʻi throughout the year, spending their time in deep water, typically deeper than 500 fathoms. These whales travel in cohesive groups typically of 5 to 15 related individuals, and are the most abundant “whale” that is present year-round.

An adult male short-finned pilot whale, with a satellite tag on the side of the dorsal fin. Photo by Robin W. Baird/Cascadia Research.

Pilot whales also dive for long periods, up to half an hour, but the large dorsal fin of the adult males and their tendency to rest during the day while logging at the surface make them easy to spot. We have catalogs of individuals of this and more than a dozen other species of whales and dolphins in Hawaiian waters, based both on our own work and incorporating community science contributions from other boaters — tour operators, fishermen and other researchers.

Off Kauaʻi and Niʻihau we’ve documented almost 500 different individual short-finned pilot whales, some seen repeatedly over spans of up to 15 years. We encountered pilot whales on four out of 14 days on the water in August 2021, with one sighting reported to us by Captain Anthony at Fathom Five Divers. We deployed three tags on pilot whales, and over the next four weeks the tagged whales moved around the island, spending most of their time off the south shore of Kauaʻi. Others that we’ve tagged off Kauaʻi in previous years have also moved on occasion to western Oʻahu, and some that we’ve tagged have been part of a broadly ranging open-ocean population, extending hundreds of miles offshore, rather than the island-associated resident population.

An adult male Blainville’s beaked whale surfacing. The teeth of adult male Blainville’s beaked whales erupt above the jaw and are referred to as tusks – they use them to fight with other males over access to females. The tusks of this male are largely covered by stalked barnacles – the white area just behind the tusks and along the back is scar tissue caused by fighting with other males. Photo by Robin W. Baird/Cascadia Research.

We encountered melon-headed whales on five different days, with groups ranging from 125 to 250 individuals — melon-headed whales are typically found in the largest groups for any species of whale or dolphin in Hawaiian waters. We found four of the five groups by working with Navy researchers monitoring the hydrophone range at PMRF, and were able to deploy three satellite tags, all of which also provided data on diving behavior. Like pilot whales, melon-headed whales tend to rest and socialize during the day and do almost all of their feeding at night, and this was very evident in the dive data obtained from these tags.

The last species of whale we encountered during the trip was a group of about 30 false killer whales, traveling east along the south shore of Kauaʻi. The Garden Isle and Niʻihau are an area of overlap between the endangered main Hawaiian Islands population of false killer whales, numbering less than 200 individuals, and the larger Northwestern Hawaiian Islands population. We deployed one satellite tag on an individual in this group and over the next 12 days this individual circumnavigated Oʻahu and spent time on Penguin Bank, returned to Niʻihau and back along the south shore of Kauaʻi, then moved back along the south shore of Oʻahu to the east. Comparing photos to our catalog, this individual was identified as one of the endangered main Hawaiian Islands population.

During the same trip we encountered four other species of dolphins, three of which are resident to Kauaʻi — spinners, bottlenose, and rough-toothed dolphins. Although most people think spinner dolphins are the most common species of dolphin around Kauaʻi and Niʻihau, in fact it is the deep-water rough-toothed dolphin that is most abundant species in the area. We estimated there were over 1,500 rough-toothed dolphins around Kauaʻi and Niʻihau using photo-identifications obtained in the first few years we worked off the islands. We’ve satellite tagged a number of individuals from this population over the years and while they generally remain around Kauaʻi and Niʻihau, they seem to prefer the waters of the Kaulakahi Channel, feeding on flying fish and mahi mahi, among others.

An adult male Fraser’s dolphin, showing the very short beak and black mask. This was our first sighting of Fraser’s dolphins around Kauaʻi or Niʻihau in 13 years of working off the islands. Photo by Robin W. Baird/Cascadia Research.

The most unusual sighting for the trip was a group of Fraser’s dolphins mixed in with a much larger group of melon-headed whales. Fraser’s dolphins are an open-ocean species that rarely comes close to shore, and this was our first sighting of Fraser’s dolphins off Kauaʻi or Niʻihau. Our August 2021 field effort, and most of our other Kauaʻi field projects over the last 10 years, have been funded by the U.S. Navy as part of their Marine Species Monitoring Program — we are learning more about their residency, movement patterns, and reactions to Navy sonar. Our projects are timed to occur just prior to U.S. Navy submarine command courses, so that we can look at the tag data to assess if and how different species respond to Navy sonar. Our August 2021 effort was the most successful yet, in terms of tag deployments (data from 13 tags on six different species), so it will provide a valuable opportunity to assess responses to sonar. We are looking forward to coming back out again in August 2022 for another field effort.

We presented results from the August 2021 effort at a meeting for the Navy’s Marine Species Monitoring Program in April — if you want to see a copy of that presentation it is available at https://www.cascadiaresearch.org/files/publications/Baird_etal2022_MSMPR.PDF  For more information on whales and dolphins in Hawaiian waters and what we’ve learned about them, we’ve created pages for each species available at https://www.cascadiaresearch.org/projects/hawaii/hawaiian-odonotocete-species. During each of our field projects we also post photos and updates on what we are seeing and learning — these are available at https://www.cascadiaresearch.org/hawaiian-cetacean-studies/updates-our-hawaii-field-projects.

• Robin Baird is a biologist working with Cascadia Research Collective, a nonprofit research and education organization. He moved to Maui in late 1998 and while only lived there for a year and a half, has returned to the islands every year since, working with a team of primarily Hawaiʻi-based researchers. Dr. Baird has conducted whale research around Kaua‘i in 13 of the last 19 years. He can be reached by email at rwbaird@cascadiaresearch.org