Changes in climate are affecting the whales’ reproductive success; researchers determined this by observing more than 1,800 right whales in the southern Atlantic. The whales do not suffer directly from warm conditions, but their food supply-mainly krill-does.
It is since 1971 scientists have conducted yearly photo-identification studies of a population of southern right whales. Researchers have created an annual index using detailed photographic information on individual females. It charts the deviation of known whale births from the expected number of calves.
Under normal circumstances, a female right whale requires three years between births. But a female needs two years to recover if a calf aborts or dies, and the interval expands to five years.
“The relatively large number of five-year calving intervals can be explained by whales needing two years to recover from a failed pregnancy,” said lead study author Russell Leaper of the International Fund for Animal Welfare.
True, this evidence does not suggest that whales are failing to get pregnant, but rather that unborn and newborn calves are not surviving!