Concho the seal pup died last week.

It was a tragic end for a baby harbor seal that was sent to Wolf Hollow Wildlife Rehabilitation Center in Friday Harboro after a Coupeville deputy marshal rescued her from the back of a car on Whidbey Island. The seal has become a “poster child” for an important, but often-ignored message: Leave seals alone.

Concho had been recuperating at Wolf Hollow since July 26. She seemed to be doing fine until she took a sudden turn for the worse Tuesday, Aug. 12.

“It happened really fast,” said Jessica Recktenwald, a seasonal staff member. “We did everything we could do.”

Recktenwald said staff members have no idea why the seal passed away. There didn’t seem to be any fluid in the seal’s lungs, which would suggest distemper.

“Who knows if it had anything to do with being kept on a boat or if it was a preexisting condition,” she said.

Recktenwald hopes a necropsy, to be performed later in the summer, will provide answers.

Concho’s sad story began in Penn Cove near the Coupeville Wharf.

Sandy Dubpernell, an investigator with Central Puget Sound Marine Mammal Stranding Network, said she received a call about the seal pup on July 24. She went down to the wharf and found that a couple had kept the baby seal in a dinghy overnight.

“They said they picked it up because it was hungry,” she said.

The couple couldn’t remember where they found the seal, so Dubpernell helped put the pup back into the water near the wharf. She watched the animal swim around for about an hour.

“She seemed fine. A good and steady little pup,” said Dubpernell, who posted signs in the area alerting people to leave the seal alone.

But the next day, Coupeville Deputy Marshal Robert Mirabal stopped a car that went through a stop sign. He discovered the five-day-old seal pup in the back seat and called Carol Barnes, the county’s animal control officer.

Barnes said she was alarmed when she saw the badly dehydrated pup. The seal was laying across the driver’s lap at that point. The woman was petting the pup and remarking on how soft the fur was.

The woman claimed a friend gave her the seal after the animal had climbed onto a sailboat — a claim professionals doubt.

Barnes drove the seal to Best Friend’s Veterinary Center in Oak Harbor, where the animal received fluids and electrolytes. A member of the Stranding Network transported Concho to Anacortes that night and San Juan Air flew her to Friday Harbor the next morning.

Rehabilitators at Wolf Hollow Wildlife Rehabilitation Center named the seal “Concho” and tube fed her. The plan was to release her in the San Juan Islands, with a group of other seals, in two or three months.

Kevin Porter, a special agent with National Oceanic and Atmospheric Administration, investigated the two separate cases involving Concho. He plans to send his report to the U.S. Attorney next week.

Both incidents may have been violations of the Marine Mammal Protection Act, which prohibits the “taking” of marine mammals. Porter said violators can face either civil or criminal penalties. The civil penalty is up to $10,000 per violation. For a criminal violation, the penalty is up to a year in jail and a fine of up to $20,000.

While Concho’s story may be unusual, Porter said people do frequently touch or move baby seals. They don’t realize that the mother is probably out getting lunch and will return.

“Most people are not intentionally trying to hurt the animals,” he said, pointing out that was definitely the case for all the people that became part of Concho’s short life.