A three-day effort to free a humpback whale from entanglement in fishing gear ended in success this week.
The Center for Coastal Studies said Thursday that the whale, a mature female named Valley, was first spotted Monday by a whale watch boat northeast of Provincetown.
The Center's Entanglement Response Team found that the whale had a heavy line lodged in its mouth, but could not free it.
Then on Wednesday the whale was spotted in waters outside Boston Harbor, where it had become anchored to the sea floor.
Rescuers using a hook-shaped knife at the end of a 30-foot pole freed the whale, which swam away.