Baby Boom Of Gray Whale Calves Complete First Migration

Baby Boom Of Gray Whale Calves Complete First Migration
Wednesday, August 14, 2013 By Susan Murphy

Credit: NOAA Fisheries Northwest - A gray whale calf travels alongside an adult gray whale to their summer feeding grounds in the Arctic.

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.

Credit: Washington State Dept. of Ecology - Gray whales travel10,000 to 14,000 miles roundtrip every year -- from feeding grounds near the Arctic to breeding lagoons in Baja California.

Wayne Perryman, a biologist with NOAA's Southwest Fisheries Science Center said births were up despite record ice in the arctic last spring that limited food supplies for newly-pregnant females.

"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.