NEWPORT, R.I. (AP) – A young finback whale that apparently separated from its mother and got stuck in a cove was euthanized after an attempt to save it failed, scientists said Monday.

On Monday morning, the ten-ton, 40-foot juvenile whale was lying on its lungs in two feet of water at the southern end of Brenton Cove, said Heather Medic, stranding coordinator at Mystic Aquarium, in Mystic, Conn., which coordinates whale rescues.

Scientists believe the whale, estimated to be about three years-old, probably became disoriented after it was separated, Medic said. Efforts on Sunday to guide the whale into open waters were unsuccessful.

“We gave it every option to go back out,” she said.

Even if the whale could have been moved to open water, it was too young to find food on its own. Without its mother, “it would wander around and around and not know what to do,” Medic said.

Finback whales, an endangered species, are the second largest type of whale after the blue whale, the largest animal in the world. There are 2,814 finback whales in the North Atlantic, according to the 2002 stock assessment from the National Marine Fisheries Service.

Shortly before noon on Monday, rescuers spent about 20 minutes giving the whale anesthesia, including delivering a calming agent into its blowhole. Then, scientists injected an overdose of barbiturates into a vein in its tail, said Larry Dunn, a marine mammal specialist from Mystic Aquarium.

The whale thrashed briefly following the shot – flapping its tail in the water, moving its head up and down and opening its mouth wide. Dunn said the spasms were a reflexive action rather than an indication of pain.

Authorities ordered dozens of spectators away from the area before the euthanization, because specialists were afraid the whale may thrash violently before its death. They were allowed to watch once scientists determined there was no danger.

The whale was first spotted by boaters in the cove, which is lined with marinas, at about 9:30 a.m. Sunday.

Medic, who was contacted about three hours later, said the whale was in good condition Sunday, but appeared disoriented. Authorities tried to coax it into open water. A state Department of Environmental Management boat began towing the whale out of the cove, and had gone about 40 yards, before the fin resisted.

Dick Masse, a DEM employee and manager of Fort Adams State Park, which borders the cove on one side, said the whale began pulling the 26-foot boat backward.

“It just seemed like it woke up and wanted to swim,” he said.

The juvenile had some red markings that suggest it may have been clipped by a boat’s propeller, but Medic said the wounds were superficial, and not responsible for the whale’s plight.

The Coast Guard attempted to tow the whale to a boat ramp around noon, but could not move it. Once the tide rose, authorities moved it and then loaded it onto a truck. They realized the whale was longer, and heavier than thought, and called for a larger truck. The fin is to be taken to the Great Swamp Management Area in South Kingstown on Tuesday, where scientists will perform a necropsy and then bury it.

Watching with his wife, John Stalk, of Portsmouth, said he came hoping the whale would be rescued.

“But we’re a witness to tragedy,” he said.

Finbacks grow to up to 80 feet long and weigh up to 70 tons, according to the National Marine Fisheries Service. They’re known as fast swimmers.

AP-ES-06-14-04 1719EDT