Ship strike may have killed Southeast Alaska sperm whale
The rare discovery of a dead sperm whale beached along Southeast Alaska’s Inside Passage has become a whodunit within a mystery, as investigators examine both the whale’s death in a possible ship strike and a crime committed after it washed ashore.
National Oceanic and Atmospheric Administration spokeswoman Julie Speegle said officials first learned of the male whale’s carcass near Juneau on March 19.
“A pilot was flying over and spotted it and reported it to us,” Speegle said.
NOAA biologists and investigators visited the carcass, which had beached on the east side of Lynn Canal on the north side of Berners Bay, the following day to conduct a necropsy.
According to a statement from the agency, fractured vertebrae and “three deep propeller slices into the whale’s side” indicate that its death was the result of trauma consistent with being struck by a ship.
"The space between the slices, the depth of the slices and associated damage indicate this whale was struck by a large vessel," NOAA veterinarian Kate Savage said in the statement. "We also took samples that will help confirm our findings."
The Lynn Canal sperm whale is only the third to be necropsied in Alaska since 1990, including a calf that stranded near Homer in 2006 and a partial necropsy of a whale stranded in Seward’s Resurrection Bay in 2009. It is the first to be found dead in the Inside Passage.
In the weeks since the necropsy, Speegle said NOAA hasn’t significantly narrowed down the range of vessels which may have been involved.
“It could have been a barge, a tugboat,” Speegle said.
Alaska Marine Highway System (AMHS) spokeswoman Aurah Landau said the state ferry LeConte had been traveling through Lynn Canal on March 19, but no whale strikes have been reported this year. State ferries had helped search for the whale after it was originally spotted on March 19.
"No AMHS vessels in the area reported a whale strike around that date," Landau wrote in an email. "In fact, AMHS’ last whale encounter was when a whale breached onto a ferry outside of Kodiak in June 2018."
Sperm whales, which typically dive to depths ranging from 2,000 feet to 3,280 feet, are more often seen along Alaska’s Pacific Ocean coastline according to NOAA. Researchers believe male whales leave equatorial waters and travel to foraging areas, including Alaska, when they are 10 to 12 years old to build up their mass for breeding.
Parts of the Inside Passage, largely carved by glaciers, are deep enough to accommodate the whales. Scientists suspect “longline bandits” among the whales may have followed longline fishing vessels into southern Chatham Strait, drawn by their catch.
“There’s anecdotal reports of sperm whales being in Chatham Strait, Lynn Canal prior to 2008,” Speegle said. “But 2008 is when we had our first official sighting of sperm whales, and that was by the Alaska Department of Fish and Game; they had a crew out on a sablefish survey.”
NOAA’s statement on the whale cited the Southeast Alaska Sperm Whale Avoidance Project, a partnership of fishermen and scientists to minimize whales’ interaction with the region’s fishing fleet. Tracking data from sperm whales has shown some of them remaining in the passage after the sablefish season, which has been theoretically linked to the whales discovering other food sources in the area.
“In fact, the stomach of this animal contained almost exclusively beaks of squid, which [SEASWAP] believes were magister armhook squid and have been seen in large quantities by fishermen in Lynn Canal,” NOAA officials wrote.
No plastics were found in the whale’s stomach, according to NOAA. Last week, Italian authorities examined the carcass of a pregnant female sperm whale that washed ashore in Sardinia containing nearly 50 pounds of plastic.
Although researchers are checking whether the Southeast Alaska whale was one of three that have frequented the area, based on tagging data, Speegle said the whale may have simply been part of a pod that moved into the area.
“This particular whale was a younger sperm whale and we think he was just hanging out with the older guys when he met his demise,” Speegle said. “He probably followed the older whales into Chatham Strait, Lynn Canal.”
Investigators are also trying to determine who was responsible for visiting the scene and removing part of the whale’s jaw, which is illegal because sperm whales are an endangered species.
“When our necropsy crew went out the first time, on [March 20], the lower jaw was still there; the teeth samples were still there,” Speegle said. “When they returned on [March 22] to get the stomach contents, the lower jaw had been removed and taken.”
The NOAA crew hadn’t left signs on the carcass advising people to avoid it between those visits, Speegle said, in accordance with policy.
“We would only take that type of precaution if the whale was in a highly populated area,” Speegle said. “If it was in a remote area, like it was, we wouldn’t want to leave any plastics that could become part of the environment.”
NOAA urges mariners to use its Whale Alert app, intended to flag whales’ locations and help prevent ships from hitting the animals. Any injured, entangled or dead marine mammals should be reported to NOAA’s 24-hour stranding hotline at 1-877-925-7773.
In addition, any parts taken from the sperm whale should be returned to the agency’s Office of Law Enforcement. Tips regarding their whereabouts are being taken by NOAA at 1-800-853-1964 or 907-586-9329.
Copyright 2019 KTVA. All rights reserved.
YOU MAY ALSO BE INTERESTED IN: