WHOI (Woods Hole Oceanographic Institute) press release: Right whale sedation enables disentanglement effort.

Whale avoidance of boats attempting disentanglement is a major obstacle for rescue teams. The new sedation technique slows the whale's reaction time, allowing boats to approach the animal and remove the fishing gear. (Georgia Wildlife Trust)

Sketch of entanglement of right whale # 3311. The whale was first spotted on January 14, 2009. It wasn't until teams could inject the animal with a sedative -- nearly two months later -- that they could get close enough to the animal to safely free it from fishing gear entanglements. (Scott Landry, Provincetown Center for Coastal Studies)