The Mystery Of Alaska's Sea Otter Deaths Continue To Baffle Scientists

An unusually high number of sick or dying sea otters has washed onto the shores of Alaska’s southern coast this year. But despite the efforts of many baffled scientists to find an answer, the exact cause of the die-off remains unknown.

More than 250 sick or dead sea otters have turned up on beaches in the Kachemak Bay region this year. Joel Garlich-Miller, a biologist with the U.S. Fish and Wildlife Service, told Hakai Magazine that this number is more than double 2014’s -- which had already been a “higher than average” figure.

Based on the symptoms of the otters that have been found, scientists believe something peculiar may be plaguing the animals. Preliminary tests suggest that toxins from harmful algal blooms and infections caused by bacteria might be contributing to the otter deaths; but given the spike in morbidity, another as-yet-unknown factor is also suspected.

“Something is hitting them harder and faster, in addition to the disease that we’re familiar with seeing, something else seems to be involved,” Marc Webber of the U.S. Fish and Wildlife Service, told Alaska Public Media last month. “That’s just speculation, we don’t have any evidence yet, but that’s what we’re seeing on the beach.”

Compounding this mystery, reports say that while some dead otters were found emaciated, indicative of a long illness; some of them appear to have died suddenly at a healthy weight, which is “even more curious,”Alaska SeaLife Center veterinarian Carrie Goertz told Hakai Magazine. 

These seemingly healthy otters act paralyzed, or “seize” up just before death, reports Homer News.

Kachemak Bay is home to about 6,000 sea otters. Since the marine mammals play a critical role in their ecosystems, experts say the mass die-off is likely a sign that the entire ecosystem is being impacted by something harmful.

In October, the Alaska SeaLife Center and the U.S. Fish and Wildlife Service announced in apress release that a team of experts had launched an investigation into the spike in otter deaths in the area.

So far, scientists say they have a few ideas as to what’s causing the animals to fall sick; but nothing concrete has been determined.

Kathy Burek, a veterinary pathologist, told Hakai Magazine that she believes the bacteriumStreptococcus infantarius subspecies coli may be one of the culprits. However, as the bacterium is quite typical in this population of otters, she suspects “there may be something else going on that’s making these infections more deadly.”

“Any time you have a disease process occurring at an unusual rate, even if it’s a known disease process, you want to figure out what’s different, what’s causing it to increase so much,” Burek said.

Burek suspects that a mystery virus may be to blame. She said, however that is could take “weeks or months” to figure out if this is true.

Halley Werner, a supervisor at the Alaska SeaLife Center, told KTVA.com in October that the spate of the sea otter deaths has unnerved her.  

“It’s scary to know there’s something out there in the wild that we may or may not be able to do anything about,” she said.