More than 1,100 gray whale calves recently completed their first 5,000-mile northward journey from the warm water lagoons in Mexico, where they were born, to the Arctic Circle.
"And then in September, when ice reaches its minimum up in the arctic, there was less ice than what’s ever been recorded in the whole time series," said Perryman. "So we had a really anomalous year in the arctic."
Perryman said another factor in play is that females are on a three-year cycle: they calve, take two years off and calve again.
"As we look back at this 20 year data set that we have, if we have very high calf production in one year, then three years later it isn’t unusual that we’ll have relatively low calf productions. Some of these females just haven’t gotten back up to being healthy enough to calf again," Perryman said.
In 2012, there were 1,166 calves born, but 2010 saw the lowest birth rate ever recorded at 254.
The whales will start their annual southern trek to Mexico in late October with sightings off San Diego starting in December.
