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West Coast gray whale strandings declared as Unusual Mortality Event, investigation coming

The National Oceanic and Atmospheric Administration (NOAA) has declared the elevated rate of gray whale strandings on the West Coast in 2019 an Unusual Mortality Event (UME), triggering a scientific investigation into the cause.

Max Kirkendall
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As of May 31, about 70 gray whales have stranded on the coasts of California, Oregon, Washington and Alaska so far in 2019, the most since 2000, when more than 100 whales stranded in what was also determined to be a UME. Two of the 70 have come ashore in Lincoln County, both in the month of April.

Outside the U.S. West Coast, British Columbia and Mexico have also recorded gray whale strandings. The eastern North Pacific gray whale population that migrates along the Pacific Coast was last estimated at about 27,000 animals.

On May 31, NOAA Fisheries declared the deaths a UME and discussed possible causes for the influx in strandings via a conference call.

“Many of the whales have been skinny and malnourished, and that suggests they may not have gotten enough to eat during their last feeding season in the Arctic,” NOAA spokesman Michael Milstein said during the call.

Along with NOAA, representatives from a variety of fisheries along the West Coast participated in the discussion as well as Oceans Canada. A consensus was met in the belief that the number of strandings is likely much higher give that many whales in remote areas will simply sink as opposed to washing ashore.

The theory of global warming, leading to the loss of Arctic sea ice, was also discussed as a possible cause.

For many years, researchers noted that more whales tended to die following years when the ice melted late in the Chukchi Sea, north of the Bering Strait between Alaska and Russia. The whales had less time to eat because they were unable to access the feeding area, making for less blubber to sustain them on their next migration.

“The sea ice has been changing very quickly over the last decade or so,” Sue Moore, a biological oceanographer at the University of Washington said. “The whales may have to shift to other prey, such as krill or other things they eat.”

The last UME event was in 2000, when more than 100 whales washed up on shore. That investigation failed to identify a cause. The deaths followed strong changes in ocean conditions in the mid 90s, and Moore said warmer water patterns might have affected the availability of prey. But without accurate samples, they were unable to pinpoint a specific cause.

“It’s sometimes very difficult to get to these whales in a timely fashion,” Moore said. “You can’t always get the kind of samples you would need for diagnostic reasons.”

Researchers have now built up an improved group of volunteers and have asked the public to help report and respond to whale deaths.

“Scientists have been able to perform necropsies on 20 of the whales this time around,” Deborah Fauquier, veterinary medical officer at NOAA’s Office of Protected Resource said.

Scientists said Friday they would continue to investigate whale strandings and work to determine a cause.

Previous News Guard story from May 3

So far this year, 45 whales have washed up along the western coastline and one of the latest currently resides in Bella Beach near Lincoln City.

The whale was discovered to be a sub-adult female gray whale, which had been dead and floating for several days before coming ashore in a moderate state of decomposition, according to Oregon Marine Mammal Stranding Coordinator Jim Rice.

“The whale carcass currently at Bella Beach originally came ashore last Thursday (April 25) on the Salishan spit, at which point I examined and collected tissue samples from it,” Rice said.

Many residents noticed the whale out in the water, but were unsure of what it actually was until it reached the shore. The confusion came from the lack of bodily structure, leading Rice to conclude a possible cause of death.

“There were several recent traumatic wounds on the body indicating that it had been attacked by killer whales,” Rice said.

Another whale recently washed up in a remote cove just north of Lincoln City. Many believed the whale to still be alive when it beached on the rocks, but by the time Rice and his crew arrived it was no longer breathing.

“So far this year there have been three gray whale strandings in Oregon,” Rice said.

The exceedingly high number of whales that have washed ashore this year has caused Rice and Bruce Mate, director of Marine Mammal Institute at Oregon State University’s Hatfield Marine Science Center in Newport, to speculate what the cause may be.

Throughout all of 2018, there were a total of 25 gray whale standings on the west coast, as opposed to the 45 already this year. Mate, who has been studying whales for almost 45 years, suspects that there hasn’t been enough food in the Arctic feeding grounds for many of the whales, seeing as how many are underweight.

“Nutritional stress is going to cause an adjustment to the carrying capacity,” Mate said.

Mate said the high number of gray whales might be teetering on the maximum number of animals the ecosystem can support. In addition, warming in the Arctic and the reduction in sea ice may be worsening the issue.

Stranding season runs from March through May, leading Mate to believe there will likely be more whales appearing on western beaches soon.

“It won’t surprise me if we see a lot more dead animals,” Mate said.

The Long Haul

The west coast gray whale travels about 10,000 miles yearly during their migration pattern, making it the longest of any whale on Earth. Whales are in the Arctic during the summer, where they feed on small creatures called amphipods. There they will bulk up for the long trip down the coast. The whales do not eat again until they return to the Arctic.

After breeding and giving birth down south, the whales start northward during the spring migration, which is when they are most vulnerable according to Mate. After giving birth many females spend energy tending to and nursing the newborn whales, often consuming up to 50 gallons of their mother’s milk per day.

According to the Gray Whale Census and Behavior project in Southern California, there are four signs that mark trouble for the gray whale population: animals arriving late to their breeding grounds, a low number of calves, skinny whales and whales washing up dead in high numbers. They have found all of those things to be true so far in 2019.


Like Mate and many other researchers, they believe the fluctuating gray whale population could just be mother nature’s way of balancing the ecosystem. In 1994, the population of gray whales jumped to roughly 25,000, according to the Marine Mammal Center.

Between 1999 and 2000 the population was trimmed by a third to just 17,000 whales. Since then the whale numbers surged to their present population of 27,000, the largest number of whales since they were being hunted in the late 1800s and early 1900s.

Although the rate of whales washing up is alarming, the gray whale population is at its highest, meaning they are in no danger of going extinct. However, researchers like Rice and Mate will be keeping a close eye on the melting sea ice in the Arctic and its impact on the food chain.

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