Seven gray whales were found dead on Alaska’s shores over the holiday weekend, sending this year’s toll in the state to 22.
According to the National Oceanic and Atmospheric Administration, a necropsy to help determine the cause of death was performed on one of the four animals that turned up around Kodiak Island. Two others were discovered in Egegik and another at Takli Island. The whales were all found between July 5 and 7.
NOAA Fisheries Alaska region spokesperson Julie Speegle told HuffPost on Friday that while the investigation of the deaths remains in its early stages, starvation triggered by melting sea ice may be a cause.
“As many of these whales have been skinny, scientists theorize there may have been a disruption in the gray whale food source due to a lack of sea ice in the Arctic last summer,” Speegle said. “Gray whales fatten up during the summer by feeding on marine life in the Arctic, mostly amphipods off the ocean floor. But when sea ice melts and retreats (as it did last summer), there is a disruption in the food web that results in fewer amphipods for gray whales to eat.”
Though Speegle did not say whether climate change could be to blame for the deaths, she noted that Arctic sea ice dropped to its sixth lowest extent on record last summer, “which may have caused a disruption in the food supply for gray whales.”
Jon Warrenchuk, a senior scientist with Oceana, an international organization focused on conservation, explicitly pointed to climate change as contributing to the deaths.
“It is certain that these whales are suffering the effects of global warming as their prime feeding habitat in the Arctic is rapidly changing,” he told HuffPost.
“The government has called these latest whale mortalities an ‘Unusual Mortality Event’ but we may very well be in the new norm, where climate extremes, persistent warm water blobs, lack of sea ice, and changing Arctic productivity makes life difficult for whales and puts their populations at risk,” Warrenchuk said.
In May, NOAA sounded the alarm by declaring an unusual mortality event on the West Coast due to a surge in whale strandings. The Marine Mammal Protection Act defines such events as “a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response.”
NOAA data shows that combined gray whale strandings in California, Oregon, Washington and Alaska have far surpassed 18-year averages for the past several months.
Necropsies of several of the whales included in NOAA’s alert revealed emaciation to be a factor in their deaths, although the organization noted that the “findings are not consistent across all of the whales examined, so more research is needed.”
Andy Rogan, a science manager researching threats to marine mammals at Ocean Alliance, a Massachusetts-based conservation organization, told HuffPost that another reason for the uptick in whale deaths could be that the population has hit its carrying capacity, which tends to fluctuate.
“This population has been recovering from commercial whaling for decades, increasing and increasing until this point, until carrying capacity has been met,” he said.
Though Rogan said further research is required to determine whether global warming is part of the problem, he speculated that “it could be a combination of both climate change-related disruption of the food-web AND carrying capacity being reached.”
This story has been updated with comment from Andy Rogan.
This article originally appeared on HuffPost.