Thousands of humpback whales (Megaptera novaeangliae) migrate to the Hawaiian Islands for breeding and calving-related activities. HMMC scientists are on the water in Kawaihae Bay each winter, observing these whales to answer a variety of basic science and conservation questions. Our recent studies include:

Abundance and Distribution One of the HMMC’s main research goals is to conduct standardized shore-based counts of humpback whales in Kawaihae Bay from shore during the peak of the whale season (February and early March). The goal is to document the presence and relative position of all marine mammals and vessels to describe and understand trends in the whale population and human use of the Bay. We recently published a paper in Marine Mammal Science on trends in the relative distribution and abundance of humpback whales in Kawaihae Bay since 1988.  

Click here to learn about our results and how we do the work

In December 2005 at the Sixteenth Biennial Conference of the Society for Marine Mammalogy in San Diego, we presented a poster titled: Using compass and reticle binoculars to measure animal position: An evaluation and comparison to theodolite data, which is based on data from our shore station work.

Whale song – Male humpback whale song is one of the most complex vocalizations in the animal kingdom, and yet scientists still aren’t quite sure why they do it. Our working hypothesis is that one way that females choose a mate is by evaluating male singers based on the acoustic qualities of their song. With help from the Norcross Wildlife Foundation, we began investigating whether songs from larger males are different than those of smaller males. Measuring the differences in song is the easy part; using a computer and special software, features such as song length and frequency composition are detectable. Measuring whale size is another matter.

Measurements of length and fluke width of stranded whales were made years ago. Therefore, if we know how big the fluke is, we can figure out how long the whale is. Thus, we had attempted to measure the length of a whale based on the size of their flukes – called photogrammetry, but that proved to be quite difficult. The research vessel, and especially the photographer, had to be directly behind the whale when a photo was taken. Simultaneously, measurements of distance from the photographer to the fluke of the whale had to be taken. The whale also had to fully extend its flukes, not curling them at the tips. After many measurements over several field seasons, we determined that the error involved in our measurements was large and made it impossible to get accurate measurements of length. Future studies, pending funding, are planned using aerial photogrammetry to compare the size of the entire whale.

Skin condition and health assessment – In the early 2000s, humpback whale researchers began to notice the increasing occurrence of “nodular dermatitis” (a.k.a. bumps) of unknown origin on humpback whale flanks. These bumps persist from year to year, and some whales have many of them. A biopsy sample from a bump taken from a very bumpy whale in 2006 indicated that the tissue had indications similar to an allergic reaction. In 2013, HMMC began collecting skin and blubber biopsy samples for analyses in collaboration with the Hollings Marine Laboratory of the National Institute of Standards and Technology in Charleston, SC to determine if trace element levels in the skin are different between whales with or without bumps. Levels of organic pollutants like PCBs and flame retardants in the blubber from these samples are being analyzed by scientists at the National Marine Fisheries Service Montlake Laboratory. Preliminary results suggest that bumpy whales may differ from non-bumpy in levels of a few trace elements. In the future, HMMC plans to continue to look into overall whale health and investigate potential viral and bacterial causes of bumps, which so far have been difficult to rule out as causes.

Whale behavior and mating system – Despite researchers spending countless hours observing humpback whales on their breeding grounds around the world, mating has never been scientifically documented. We are intrigued by pairs of whales that stay in one place and dive for long periods (15 minutes or more). We call these pairs "longdive-time dyads" (LDDs) If the pair is composed of a male and a female, we suspected that they might be mating pairs. Since it is not easy to tell male and female whales apart visually, we collected biopsy samples that were genetically analyzed by the Cetacean Conservation Genomics Laboratory at Oregon State University to determine the sexes of whales in these LDDs. Our suspicions were confirmed, in that many of these were male-female pairs.

Whale hormone studies – Basic research on the level of reproductive hormones (testosterone, progesterone, estrogen, cortisol) has the potential to reveal new discoveries about pregnancy, stress and adress a host of over questions. HMMC is working with the College of Fisheries and Ocean Sciences and others to develop a humpback whale pregnancy test that uses progesterone levels in blubber biopsy samples paired with sighting histories of females known to be with or without a calf the following year. Results are promising but still pending.

SPLASH – In 2004-2006, HMMC participated in SPLASH, which stands for Structure of Populations, Levels of Abundance and Status of Humpbacks. This was an unprecedented international collaborative study that spanned the entire North Pacific. Researchers on all the main Hawaiian Islands, as well as the U.S. West Coast, Japan, Mexico, Central America, the Philippines, Russia and Canada simultaneously collected humpback whale data in each area. Over the course of three winters, with help from our dedicated volunteers, HMMC conducted 86 surveys off Hawai‘i Island that resulted in fluke photographs from about 750 whales. Additionally, we collected over 400 biopsy and sloughed-skin tissue samples. This study found that the entire North Pacific population numbered between 18,000 and 21,000, with over 50% wintering in Hawai‘i. Most of the Hawaiian humpback were relighted in Southeast Alaska and the Gulf of Alaska. More details can be found in the Final Report.