Endangered right whales are leaving Georgia waters after researchers documented 20 newborns during the calving season that ends this month.
As the whales were heading north for the summer, an aerial survey team spotted the last of the calves swimming with its mother off Tybee Island a week ago.
"Twenty calves is slightly above average, so that's encouraging," said Clay George, a biologist with the Georgia Department of Natural Resources.
Right whales are highly endangered, with researchers estimating as few as 350 still exist. The large whales are closely monitored every December through March when they migrate to the warm waters off the southern Atlantic coast to birth their young.
The number of calves born each year has varied widely in the last 20 years. Only one calf was documented in 2000, but the next year researchers spotted 31, said Tricia Naessig, right whale survey coordinator for the EcoHealth Alliance.
The 2011 calving season was just a notch better than last year, when 19 right whale calves were reported off the U.S. coast.
Entanglement in fishing gear poses one of the greatest threats to right whales, and survey teams saw five entangled whales this season. Wildlife biologists managed to sedate one of the whales and remove the fishing lines — a rare feat in the wild — but the whale was later found dead.