Whale watchers in California will soon discover what those in Mexico already know: that a phenomenal baby boom has occurred, boosting the Pacific gray whale population by more than 1,000.
Census takers in the species’ largest nursing area — Baja California’s Ojo de Liebre Lagoon, or Scammon’s Lagoon — last month counted 817 gray whale calves, the highest tally in 20 years, according to Mexico’s National Commission of Natural Protected Areas (CONANP). Another census recorded 836 baby gray whales.
Nearly 100 newborns were counted in San Ignacio Lagoon to the south, and dozens of calves have been observed by whale-watching crews in Magdalena Bay, even farther south on Baja California’s Pacific coast.
Wayne Perryman, leader of NOAA’s Cetacean Health and Life History Program, said a likely key factor contributing to the boom is a diminished ice cover in recent years in the whales’ summer feeding grounds off Alaska.
“We have had years with calf production ranging from a few hundred to over 1,500,” Perryman said. “One factor that explains a lot of this variability is the distribution of seasonal ice in the Arctic during the spring of the previous year.
“Ice may form a barrier to the northbound pregnant females in years of heavy ice. This blocks their access to feeding grounds and has a negative impact on existing pregnancies.
“The last few years, ice has melted quickly and we have had very good levels of reproduction. My guess is this year our estimate of northbound calves is likely to reach near 1,500.”
Perryman leads a calf survey off Piedras Blancas in Central California each March through May.
The past few seasons have been productive for gray whales, perhaps due to climate change and shrinking Arctic ice.
Alisa Schulman-Janiger, who leads the ACS/LA Gray Whale Census and Behavior Project at the Point Vicente Interpretive Center in Southern California, said three of the 33-year-old project’s highest counts have occurred during the past four seasons.
The highest was 318 northbound calves last season — 15 percent of the total gray whales counted. (Perryman’s estimates are based on actual counts, factoring in whales likely missed during the night and in poor weather.)
Gray whales, which were once hunted to near extinction, now number about 22,000, including this season’s bumper crop of babies.
The cetaceans spend summer months foraging on small crustaceans called such as amphipods that live on the sand and mud. The whales migrate 5,000 to 7,000 miles to Baja California each winter to give birth, nurse and mate.
The 1,000-plus babies currently in the lagoons will embark on their first journey to Arctic waters in April and May, after the other whales have left.
Baby gray whales are usually accompanied only by their moms, who try to keep them on course and protect them from fishing nets, boats and hungry killer whales.
Many won’t make it, but enough will survive to help boost a recovering population – gray whales were removed from the endangered species list in 1994 – and, of course, provide lasting memories for whale watchers along the West Coast.
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