Whale Watching: The Tale of a Whale’s Trail

By Elizabeth Argyle, Birch Aquarium naturalist

It’s nearing the end of January and San Diego is back in its rhythm after a long holiday break. While locals may have returned to their respective jobs and schools, something exciting is happening in the waters not too far from the city center. Gray whales are making their annual migration south just off the coast of San Diego. And Birch Aquarium at Scripps is teaming up with Flagship Cruises & Events to get in on the action with daily cruises.

Hundreds of whales are making their migration south to one of three lagoons in Baja California, Mexico. These 45 feet long, medium-sized, baleen whales are migrating on their annual journey to their breeding and birthing grounds in the safe, warm waters off the coast of Mexico. Whale watchers have been delighted by numerous sightings of these magnificent animals as they surface just yards away from whale watching vessels.

Sounding Diagram

Gray Whale Sounding Diagram

During their approximate 5,000-mile southward journey, gray whales demonstrate a unique behavior of 3-5 surface dives followed by a single deeper dive known as a sounding dive. Following each subsequent shallow dive, the whale surfaces and exhales. This week, our guests were delighted by the sounds made by a pair of gray whales as they exhaled through their blowholes. And then there was a gasp of delight as the pair fluked their tails signaling the deeper sounding dive that was to follow.

Slick Surfaces

While the pair took their deep dive, a Birch Aquarium at Scripps naturalist took the opportunity to tell the guests about the very visible trail that was left on the surface, just above the diving whales.

This trail, known as a whale’s footprint, marks the spots where the whales had breached the surface for their breaths. The slick waters of the footprint were once thought to have been created by a whale’s oil seeping out of its body and floating on the surface. Scientists have since discovered that a whale’s footprint is merely a consequence of the whale’s forward motion propelled by its tail flukes.

gray whale footprint

A visible train in the water, known as a gray whale’s footprint, marks the spots where the whales had breached the surface for their breaths.

This slick puddle is important to whale research. On a calm day, a line of footprints can be seen on the ocean’s surface indicating the direction of the migrating whales. The captain aboard the Flagship whale watching vessel Marietta uses this trail to navigate his vessel alongside the whales (at a distance respectable to the whales, of course).

After a few more delightful encounters with the pair, the whale watchers aboard the Marietta bid the whales “adios,” as the whales had just crossed the border into Mexican waters. A tribute to their nature, the two whales returned the “goodbye” with a “wave” of their tail flukes as they made one more sounding dive.

All that was left to see was the whale’s trail, pointing southward, in the direction of their journey’s end.

Whale watching coupon

Daily whale watching cruises leave at 9:45 a.m. and 1:30 p.m. from Flagship Cruises & Events at 990 N. Harbor Drive in downtown San Diego. For more information and to download a $5-off whale watching coupon, visit the Birch Aquarium Whale Watching page.