SEATTLE (AP) -- Scientists say a baby has been born to an endangered group of killer whales off Washington state, marking the fifth birth among the region's three pods since December.

Members of the Center for Whale Research spotted the calf, named L122, on Monday. The baby was swimming with its mother, a 20-year-old orca named L91 that's part of the Puget Sound's L-pod.

The researchers were measuring the whales from the air when they spotted the pair near Sooke, British Columbia.

The mother and calf spent most of Monday "fishing" in Haro Strait, just west of San Juan Island, and were later joined by members of the J- and K-pods.

Researchers say they hope this year's "baby boom" represents a turnaround in what has been a negative population trend in recent years.