Researchers are reporting a disappointingly sparse calving season for endangered right whales off the southern Atlantic coast.

Scientists say only six newborn calves were spotted this past winter off the coasts of Georgia and North Florida, where right whales migrate each year to give birth in the warmer waters. Clay George of the Georgia Department of Natural Resources says that's far below the average of 20 calves per year that researchers have seen for the past decade.

The Savannah Morning News reports experts suspect the low number of births is related to a food shortage that affected many whales in the summer of 2010. Right whales have a gestation period of a year.

Scientists estimate as few as 400 right whales remain.