By Ruby Pap
Until recently, I unconsciously used the term “whale seaso” without fully appreciating that besides our famous humpback visitors, there are many other species that are resident whales in Hawaiian waters. This is the subject of a new book by Dr. Robin W. Baird, Research Biologist with the Cascadia Research Collective.
The Lives of Hawai‘i’s Dolphins and Whales was just published last November by University of Hawai‘i Press. I picked up a crisp new copy at Costco last month, and it is a beautiful addition to my library. It covers all of the 25 species that have been recorded in Hawaiian waters, 18 of which are toothed whales and dolphins, odontocetes, and seven species which are baleen whales (mysticetes). Eleven of these species actually make Hawai‘i’s marine slopes their year-round home.
Baird has more than 17 years of research in Hawai‘i, with nine years in waters off Kaua‘i. I had a chance to talk story with him by phone last month about his years on the water and his insights about Kaua‘i.
Because the popular spinner dolphins and humpback whales are well understood in Hawai‘i by a large body of research, Baird has focused his career getting to know the lesser-known toothed whales: rough-toothed dolphins, dwarf sperm whales, false killer whales, Cuvier’s beaked whales, pygmy killer whales, melon-headed whales and more.
Baird and his team have spent hundreds of hours each year surveying species, recording behavior, photographing individuals, collecting biopsy samples for genetic and toxicology studies, and tagging the animals to examine behavior and movements.
A group is deemed a “resident population” based on long-term photo-identification showing re-sightings of individuals, genetics showing they are distinct from neighboring populations, and satellite tagging showing limited movement around the islands.
The research has revealed some interesting findings and questions for Kaua‘i. Out of the eleven resident species of toothed whales in Hawai‘i, only four of them have resident populations in Kaua‘i’s waters. Compare this with Big Island’s 11, Maui Nui’s six or seven, and O‘ahu’s seven.
The Kaua‘i residents include spinner, rough-toothed and bottlenose dolphins, and short-finned pilot whales. False killer whales are present too, but they are resident to the main Hawaiian Islands as one group.
Why only four resident populations on Kaua‘i? With funding from the Navy and the National Marine Fisheries Service, a couple things Baird has been looking at are population structure and assessing which species are sensitive to sonar.
Sonar has been used by the U.S. Navy for more than 40 years for tracking submarines and training activities. A large proportion of Hawai‘i’s sonar activities are in waters between Kaua‘i and Ni‘ihau.
Toothed whales use a variety of sounds for things like finding food, social activities, keeping track of group members and breeding.
“Sound is very important to the lives of these animals,” Baird said.
Of the species that are not resident in Kaua‘i waters, five are known to be susceptible to the impacts of navy sonar. For example, beaked whales are easily startled and will flee from sonar. Cuvier’s beaked whale has no resident populations off Kaua‘i.
Further, the species that do call Kaua‘i waters home, the rough tooth and bottlenose dolphins for example, don’t react to the sonar in the same way and appear to be more tolerant to sonar.
Baird is quick to point out that the implication that sonar is the cause is strictly conjecture, since we don’t have the whale population information from pre-sonar days (more than 40 years ago) — but his insight is valuable nonetheless.
Other important conservation issues discussed in the book include the impacts of persistent organic pollutants, dolphin and whale watching tours, and the conservation saga for endangered false killer whale in Hawai‘i. I highly recommend you add it to your library!
- Ruby Pap is a Coastal Land Use Extension Agent at University of Hawai‘i Sea Grant College Program. She can be reached at firstname.lastname@example.org.