There were no obvious physical signs suggesting a cause for the mass stranding of pilot whales at Kauai’s Kalapaki Beach Oct. 13.
But the testing has just begun on samples taken from five dead whales for possible factors, which could include disease, parasites, poisons, injury, organ failure and others.
“At this time, we have not yet determined a reason for the stranding,” the National Oceanic and Atmospheric Administration’s Pacific Islands Regional Office’s Marine Mammal Response team said in a statement.
“Mass strandings for this particular species are fairly common globally. Since pilot whales are social, when one individual strands, others tend to follow (not necessarily for the same cause of stranding),” NOAA said.
A pod of a dozen or so pilot whales entered Nawiliwili Bay during the night of Oct. 12-13. The whales swam onto rocks of the Kalapaki Bay jetty and later onto Kalapaki Beach shortly after dawn.
Two young male whales died on the beach immediately following the initial stranding. Others attempting to strand were pushed back to sea, but ultimately three more died, for a total of five.
There were unconfirmed reports that sharks may have attacked two more whales, whose remains were not collected.
The stranding generated a massive responses on Kauai. Several hundred people crowded the beach, including Native Hawaiian cultural practitioners who conducted ceremonies for the whales. The marine mammal science and medical response was also significant.
“Personnel from the University of Hawaii (UH), NOAA Fisheries, Hawaii State Department of Land and Natural Resources, and volunteers worked together to conduct a necropsy (post-mortem examination) on all five whales to investigate the cause of stranding,” the NOAA statement said.
The necropsy teams included both Honolulu-based and local veterinarians and pathologists, visiting marine biologists familiar with marine mammal necropsies, and local volunteer marine mammal response team members.
Many rushed to the scene to assist in the massive work of studying the five black whales, each weighing several tons, which were later buried with Hawaiian cultural protocols.
The whales did not appear emaciated, and there were no apparent ailments that might suggest a reason for the strandings.
“The preliminary necropsy results showed no obvious cause of death. Samples were taken and sent out to labs for histology (the study of microscopic structure in tissue) analysis. Histologic examination of these tissues may provide more insight into the general health of these animals as it may relate to possible infectious pathogens, toxins, trauma, and individual organ function,” NOAA said.
Although some were concerned that Navy sonar, the use of high-power munitions in the ocean, toxins from the August and September applications of diphacinone rat pellets at Lehua Island off Niihau or other activities caused the stranding, NOAA says none of those have been determined to be the culprit.
NOAA said it confirmed with the Navy that there was no mid-frequency active sonar being employed in the Kauai area around the time of the stranding. That is the frequency that has been linked to changes in whale behavior. The Navy also reported no use of explosives in the area.
Whale liver tissues will be tested for the presence of diphacinone, but those results are not yet available.
NOAA reported that its ship, the Okeanos Explorer, was operating off Honolulu the day before the stranding. It has the capability of deploying high-power beams in the ocean for imaging of the seafloor, but those systems were not in use that day.
Marine mammal teams searched nearby coastlines after the stranding, in case other members of the pilot whale pod came ashore, but none was found.
Jan TenBruggencate was the science and environment writer and Kauai Bureau Chief for the Honolulu Advertiser. He left to start a communications consulting firm, Island Strategy LLC. His science writing has generated awards from the Hawaii Audubon Society, Hawaiian Academy of Science, The Nature Conservancy, the Conservation Council for Hawaii and others.