Climate Change and Gray Whales


Historically, gray whales keep to a strict schedule.

The majestic animals leave their Alaskan feeding grounds in October and swim an epic 12,000 miles to breed and give birth in the lagoons of Baja California. They pass by San Diego in early December and head northward again by late March.

In the past few years, however, naturalists with Birch Aquarium at Scripps Institution of Oceanography at UC San Diego have noticed a change in this timetable while leading whale watching tours out of San Diego Bay. The whales have begun arriving later and later.

The aquarium naturalists were not the only ones to notice a change. Some scientists are now pointing to climate change as a possible reason for the delay.

Researchers studying the Arctic region have found that warmer waters are having a significant impact on ocean food webs. The polar regions bear the greatest brunt of climate change, and climbing temperatures have begun melting ice that used to be impassable. In the Arctic, this increases competition for food as more fish migrate through areas where gray whales historically feed upon crustaceans, plankton, and mollusks that they dredge from the ocean floor.

As a result, gray whales are traveling farther north to feed, impacting the timing of their migration south. As the planet continues to warm, scientists say gray whales may seek new feeding areas along the migration route or remain even longer in polar waters during winter.

This year, Birch Aquarium at Scripps naturalists began seeing whales in San Diego in late December. You can experience the migration firsthand during daily whale watching tours offered through the aquarium and San Diego Harbor Excursion. Throughout the winter, approximately 20,000 gray whales pass San Diego during their journey to and from Baja California – the longest known mammal migration.

On board, naturalists share information about gray whales, the ecology and history of San Diego Bay, and Scripps Oceanography. Dolphins, sea lions, and marine birds typically make guest appearances.

Whale watching tours run now through March 29, 2009. Three-and-a-half hour cruises leave from downtown San Diego in the morning and afternoon. Each trip is different, and the views are always stunning.

For a longer and more intimate adventure, Birch Aquarium at Scripps offers special excursions to the Baja lagoons where gray whales play, rest, and investigate their curious visitors. These extended three, five, and six-day trips – coordinated through Andiamo Tours Mexico – take participants to the heart of gray whale birthing grounds and up close to these amazing animals. Accommodations, naturalist lectures, and new friends make these adventures unforgettable.

For more information about Birch Aquarium at Scripps’ whale watching programs, visit

--Jessica Z. Crawford

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