GLOUCESTER, Mass. — For the highly endangered North Atlantic right whale, the year has begun badly. One young whale that had become entangled in fishing lines was found dead in January off Virginia. Worse, not a single newborn has yet been spotted by scientists flying over the whale’s calving grounds off Florida and Georgia.

Last year wasn’t good, either. Only five calves were known to have been born, and at least 17 whales died.

Only about 450 of these whales remain. Once decimated by commercial whaling, the right whale had been thought to be making a slow return in recent decades, with its numbers rising to about 480 in 2010 from approximately 270 in 1990. But their recovery has since faltered and their numbers are declining. If we don’t act now, in a little over 20 years, the breeding females alive today may all disappear, leaving little hope for the species. How did this happen, especially since the right whale has been protected from hunting for decades?

These days, the whales are dying not from harpoons but from collisions with ships and injuries from increasingly strong fishing gear and ropes. The whales’ migration route from their calving ground to their summering areas in the Gulf of Maine and Bay of Fundy cross innumerable shipping lanes and areas filled with millions of lobster and snow crab traps and thousands of miles of fishing line. Disasters are inevitable. Eighty percent of known right whale deaths are caused by humans. Our actions may be unintentional but they have been catastrophic.