Maine is seeing a significant increase in the number of harp seal strandings in 2019, and marine researchers and rescue officials are not sure what is causing the sudden surge.

Reports of tired or weak seals along the coast come after more than 1,000 seals – mostly harbor seals – were found sick or dead along the Maine coast in 2018.

Federal biologists have not found any evidence that the harp seals are suffering from the distemper virus that afflicted harbor seals last year. A federal official and the head of a Maine marine mammal rescue agency said the harp seal strandings may be related to a lack of coastal snow and ice this winter for the seals to eat, causing them to become dehydrated.

Some harp seals have been seen eating sand, a possible response to being dehydrated and mistaking it for snow, according to a federal marine mammal response coordinator.

“I don’t know the answer to why they are dehydrated. But I feel as though there are some underlying environmental changes that are going on,” said Lynda Doughty, director of Marine Mammals of Maine, a Harpswell-based nonprofit marine rescue organization.

Since January, harp seals have been turning up on beaches, floats, docks, ice floes and even in some backyards in towns and cities along Maine’s coast. Unlike many of the harbor seals that washed ashore dead last year, most of the harp seals are alive but appear tired and, in some cases, dehydrated.

The spike in strandings is happening in Maine and as far south as New Jersey and Delaware, according to an official with the National Oceanic and Atmospheric Administration’s Greater Atlantic Region Office in Gloucester, Massachusetts.

Marine Mammals of Maine said it has responded to about 70 stranded animals since Jan. 1. The majority of those compromised seals were juvenile harp seals 1 to 2 years old. That compares to nine harp seal strandings in Maine during the same period last year, Marine Mammals of Maine said.

Those numbers are slightly different from data provided by NOAA, which show Maine strandings increased from six last year to 66 by Feb. 20 this year.

Maine’s network of responders often monitors the animals to keep them from being disturbed while they rest, but some seals that were visibly ill or injured have been captured and placed in rehabilitation facilities such as the Marine Mammals of Maine facility in Harpswell. About 30 of the 159 animals reported from Maine to Massachusetts were dead when they were found, NOAA said.

Harp seals are an Arctic species that spends summers in icy seas around Greenland and Newfoundland, unlike the harbor seals that are ubiquitous along the Maine coast each summer. Harp seals consume snow and ice to stay hydrated and, like other species that rely on an Arctic climate, can be vulnerable to changes in environmental conditions that affect access to sea ice and the timing of freezing and melting cycles, NOAA said.

Due to their wide range, harp seals can swim without food for days and need to rest for prolonged periods, Doughty explained. That may be why people are spotting seals in strange locations – like residential backyards.

Marine Mammals of Maine had three young harp seals at its rehabilitation center Monday.

“Most of our animals are dehydrated,” said Doughty.

Doughty said the dehydration evident in the stranded seals could be due to a lack of snow and ice along the New England coast, especially in southern New England. She said further study needs to be done before scientists can link the strandings to climate change. Doughty said she would like to compare data with Canada, which is where many harp seals are born before migrating south.

Federal data clearly show a milder-than-normal winter along the New England coast, with warmer temperatures, more rain and less snow.

Since Dec. 1, Portland has seen more rain than normal and 34 inches of snow, which is 8 inches below normal, according to the National Weather Service. Boston has measured 10 inches of snow, about 20 inches less than normal, according to the federal data.

Ainsley Smith, acting marine mammal response coordinator for NOAA’s Greater Atlantic Region, also said a milder winter and absence of snow on beaches and rocky shorelines, particularly in states to the south of Maine, could be the reason so many animals are dehydrated.

Smith said NOAA researchers have come across several cases of harp seals that had eaten sand mixed in with snow causing them to become ill, dehydrated and disoriented.

“Harp seals eating sand seems to be unique to their species,” Smith said. “We don’t typically see other seals exhibiting that behavior. We usually observe it associated with a stress response. It could be that an animal that isn’t feeling well may try to rehydrate, mistaking sand for the more familiar snow.”

Smith said NOAA could not immediately provide historical stranding data that might show whether past mild winters also corresponded with elevated stranding numbers.

Despite the high rate of dehydration, the stranded seals are otherwise pretty healthy in most cases, and are exhibiting normal behavior, Smith said.

Last year, a mass die-off of harbor seals along the New England coast was linked to the distemper virus. More than 1,500 harbor seals and gray seals were found along the New England coast, and large numbers of them washed ashore dead, according to NOAA. The number of dead or sick harbor seals dropped off dramatically by November, but remained above average.

NOAA found that the main pathogen present in most of the dead seals was phocine distemper virus, a disease that is especially virulent among harbor seals.

Research into that so-called unusual mortality event is continuing, and researchers have so far not found evidence of a link to the more recent harp seal strandings.

“Preliminary tests have been negative so far,” Smith said when asked if the distemper virus had been detected in the stranded harp seals. “We will continue to monitor the health of all stranded seals to make sure we have the best information on their health.”

Smith and Doughty said their greatest concern is that people may try to get too close to a seal when it is resting. They said people should “give them space” and not feed the seals.

Doughty said the presence of humans can cause seals to stress eat.

“They really need to rest and regain their energy. People should leave them alone,” Doughty said.

Staff Writers Peter McGuire and John Richardson contributed to this article.

Dennis Hoey can be contacted at 791-6365 or at:

dhoey@pressherald.com