Pilot Whale Stranding CSI Kaua‘i

By Ruby Pap

A paddleboarder was authorized by NOAA to help guide the whales back out of the bay. There were additional vessels assisting with that effort, including an ocean safety jet ski, Capt. Tara Leota in her boat, a paddle club canoe, and several other paddleboarders. Photo by Jamie Thomton/NOAA Permit 18786

It was a seemingly beautiful morning on Kaua‘i on Oct. 13, 2017. I was staring out the bus window on the way to work when I received an alarming text — a picture of two short finned pilot whales on the beach at Kalapakī Bay. By the time I got there, it was clear I wasn’t the only one concerned. There were official agents guarding the dead whales, Hawaiian cultural practitioners giving blessings, and lifeguards, firefighters and volunteers in the water working to save the others.

There were also many helpless onlookers such as myself trying to find out what happened. As I mingled through the crowd, I could already hear theories brewing. Navy underwater explosions, vessel sonar and rat poison were a few of the popular ones. It is only natural to want answers, and to look for a single “smoking gun.” In many cases, however, the answers are not clear. Scientists are investigating the Kalapakī stranding on a number of fronts through a complex process not unlike a crime investigation.

A fire crew from Kaua‘i County was quickly trained on site by NOAA staff to intercept a whale to avert further strandings. Pushing whales back out is usually not the right thing to do and is viewed as inhumane. Marine mammals typically strand because they are sick or dying. Mass strandings are different, as many of the pod are usually healthy and only strand due to the tight social bond in the pod. The fire crew was given instructions to intercept any whales that were attempting to strand before they hit the beach, and to do a quick assessment of the whale before turning it back out. If it was struggling to swim or stay upright, they were to allow it to come ashore. Photo by Jamie Thomton/NOAA Permit 18786

So, the victims: A group of 17 short finned pilot whales, two of which died on the beach and three were found floating dead in the afternoon. Preliminary results indicate this group was likely part of an open-ocean population.

According to a state legislative briefing conducted by Dr. Christie West from the University of Hawai‘i, potential causes for stranding include disease, “following the leader,” biotoxins, marine debris, boat strikes, and underwater noise such as sonar and vessel noise. Well-documented historic events show pilot whales are known for mass stranding. The groups have strong social bonds and tend to follow one another.

The science and impacts surrounding Navy sonar has become increasingly documented and publicized in the last few decades. It can cause acoustic trauma to whales’ inner ears and decompression sickness where gas bubbles form in the blood vessels and organs. In the Kalapakī case, however, the Navy indicated it was not doing any exercises within five miles and 24 hours before the event.

In order to get accurate data on dead whales, it is extremely important to examine the animals internally and externally when they are fresh. This is the necropsy stage. Results show the dead whales were in good body condition with full stomachs. Of particular note is that a considerable amount of marine debris (12-15 pounds) was found in the stomach of the large dead adult male.

Next, samples of tissues and organs are put under the microscope during the histopathology phase. Results thus far have indicated no signs of infectious disease that could cause a mass stranding. This suggests there was some kind of acute cause. In the adult female, bleeding was found on the abdominal wall in the fat emboli of blood vessels. This could be indicative of acoustic trauma but no gas bubbles were found, so experts are leaning towards blunt trauma from stranding as a potential cause. Pending inner ear electron microscopy results will hopefully help detect if there was any acoustic trauma.

Sabra Kauka, along with Mayor Bernard Carvalho Jr., conducting Hawaiian protocols at the mass stranding event at Kalapakī Bay Oct. 13. Photo by Jamie Thomton/NOAA Permit 18786

Another important finding is that no rodenticide was detected in liver samples, meaning the Lehua Seabird Restoration Project is not to blame.

David Schofield, Regional Marine Mammal Response Program Coordinator with NOAA emphasized the difficulty with finding a definitive cause for mass stranding, but was quick to point out the overall decline in health of the world’s oceans and the increase in strandings over time. Vast amounts of marine debris, marine pollution, and climate change are a huge part of the problem.

“We’re going to continue to gather as much info as we can and continue to be as transparent as we can,” Schofield said of the Kalapakī stranding, adding a final report is not expected for a year or more, as “some answers beg more questions.”

• Ruby Pap is a Coastal Land Use Extension Agent at University of Hawai‘i Sea Grant College Program. She can be reached at rpap@hawaii.edu.