Researchers have a new tactic to save endangered whales tangled in fishing line - get them to calm down with sedatives shot from a dart gun so they can pull closer and cut the potentially fatal gear away.
The method was used on January 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 in Massachusetts who was on the rescue team.
The same team has tried the technique during one other rescue of a free-swimming whale.
Wildlife authorities for years have tried different ways to save whales tangled in gear that cuts their flesh, restricts feeding and causes infection and starvation. 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 autumn 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 same period. Experts say those numbers only include dead or tangled whales that have been spotted, meaning other whales may die unseen.
"It's a very slow, painful death," said Michael Walsh, associate director of the Aquatic Animal Health Programme at the University of Florida. The former SeaWorld vet 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 and restrict its movement. Crews then use pole-mounted knives to cut off entangling gear.