Preliminary results of a necropsy have revealed a whale lodged on the bulbous bow of the Sapphire Princess cruise ship last week was likely dead before the impact.
An adult female humpback became lodged on the ship on July 28 while it was in Tracy Arm en route to Juneau. A team from the National Oceanic and Atmospheric Administration Fisheries and the Alaska Sea Life Center performed the necropsy on Friday to determine what killed it.
"Scientists found that this was a complex case, as evidence indicated that several events had likely transpired by the time the whale was found on the bow of the cruise ship," NOAA said in a press release.
Lead veterinarian Dr. Pam Tuomi from the Alaska Sea Life Center and veterinarian Dr. Kate Savage of NOAA Fisheries agreed on the events that most likely happened, according to the press relase.
A missing pectoral fin indicates the whale made contact with a boat and lost the fin in the propeller. This could have led to debilitation or death.
A large absence of the ventral pleats in the lower jaw indicated that it may have been then scavenged by killer whales, which they are often targeted.
The examiners determined that the Sapphire Princess struck the whale's body after these events, trapping it on the bow overnight.
While the necropsy was to help discover what happened to the animal, it was also used as a research opportunity.
"Our first priority is to try to determine cause of death," said Aleria Jensen, NOAA Fisheries standing coordinator for Alaska. "But there is also a tremendous amount we can learn from an animal like this about, like, history, feeding habits, exposure to toxins and impacts from human activities. Stranded marine mammals can really be considered sentinels for marine ecosystem health."
Samples from the skin, muscle, blubber, liver, kidney, ovaries, stomach contents, parasites, urine and feces will be sent to various laboratories to test for contamination genetic toxin exposure.
One of the eyes was recovered to help determine the whale's age.
Researchers are also trying to match the markings on the tail flute to photos in Southeast Alaska whale catalogs.
The information released in Tuesday's preliminary report is not definitive. NOAA said it could be several months before final results are reported.
According to this report, the necropsy was conducted under the umbrella of the Alaska Marine Mammal Stranding Network. This is part of a larger network that monitors marine mammal health and responds to mammals in distress and also to reports of dead ones. Its activities are authorized by the Marine Mammal Protection Act. As this case involves a humpback, it also works through the Endangered Species Act.
NOAA stated reports of ship strikes with whales appear to be increasing, and this could be an indicator of increasing humpback populations or improved reporting efforts.
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