Sedation used to free whale from fishing line

The method was used Jan. 15 off the Florida coast to free a young North Atlantic right whale from about 50 feet of line wrapped through its mouth and around its flippers. A satellite monitor attached to the whale during the rescue attempt this month shows it survived.

“It’s a big step for us,’’ said Michael Moore, a senior research specialist at the Woods Hole Oceanographic Institution who was on the rescue team. The same team has tried the technique during one other rescue of a free-swimming whale.

For years, wildlife authorities have tried different ways to save whales tangled in gear. It is a major threat to the 300 to 400 critically endangered North Atlantic right whales that remain. They generally migrate seasonally from the Lower Bay of Fundy in Canada during the summer to calving grounds off the Florida coast in the fall and winter.

At least two North Atlantic right whales are known to have died from entanglement between 2005 to 2009, although 28 were observed tangled in that period. Specialists said those numbers only include dead or tangled whales that have been spotted, meaning others may die unseen.

“It’s a very slow, painful death,’’ said Michael Walsh, associate director of the Aquatic Animal Health Program at the University of Florida. The former SeaWorld veterinarian helped develop the sedative mixture.

Once tangled whales are found, rescue teams generally tie boats and buoys to lines trailing from the animal to slow it down. Crews then use pole-mounted knives to cut off entangling gear.

The techniques are imperfect. Staying behind a whale is a safe for humans, but it’s difficult to reach gear wrapped around the front of the animal.