A dead humpback whale which washed up on Admiralty Island last week was likely struck by a vessel, officials say.
Results of a Saturday necropsy showed signs that the whale had suffered a fractured skull, bruising and hemorrhage — indications of trauma likely caused by a vessel strike, according to the National Oceanic and Atmospheric Association spokesperson Julie Speegle.
NOAA isn’t certain yet what killed the whale, Speegle said, but a vessel strike is the “most likely explanation” at this time, Speegle said.
“If you think about the marine environment, there’re not too many obstacles other than a vessel that could cause this type of injury,” Speegle said.
Lead NOAA veterinarian Kate Savage led a team of 10 volunteers and scientists to investigate the whale’s carcass, Speegle said. The team took tissue samples, including from the whale’s ear, which have been sent to labs for analysis. They’re hoping to find out the cause and time of death.
The team was able to establish that the 38.7-foot whale was a “sub-adult” male, which is a whale that has not reached sexual maturity; it’s believed to be between 2 and 5 years old. Fully-grown adult humpback whales grow between 48 and 60 feet. Researchers are hopeful that results from further tests, which won’t be available for at least six months, will provide some answers as to how the whale died.
Savage said in a prepared statement that the team was assisted by reports from citizens, which helped researchers narrow down the whale’s location and to establish a range for the time of death.
“The quicker we get reports on marine mammal strandings, the more information we can get when we perform a necropsy, so we certainly appreciate timely reports from the public in a case like this,” Savage said.
The number of fatal vessel strikes on whales in the Alaska Region has been mostly steady since about 2011, Speegle said.
“Typically, we do have a few whale deaths per year with blunt force trauma which is indicative of a whale strike,” she said.
NOAA has not received any recent reports of vessels striking a whale, Speegle said.
Whether or not a vessel would be fined or otherwise held responsible for a whale strike would depend on the circumstances, NOAA Law Enforcement Officer Bob Marvelle said. Federal law requires vessels do not approach within 100 yards of a humpback whale and do not enter the path of an oncoming humpback whale, causing them to surface within 100 yards of a vessel. Slow, safe speeds and a respect for the normal behavior of a whale, like bubble net feeding, are also required of vessels moving through whale territory.
In 2016, an endangered fin whale was found dead on the bow of a cruise ship in Alaska.
If a vessel strike occurred when these rules weren’t being observed, it might be held responsible. The NOAA Office of Law Enforcement is investigating the incident.
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