Whales in San Francisco Bay sign of warming Pacific waters

Calm water glittered on San Francisco Bay beneath brilliant blue skies one morning last July. That it should be so sunny and warm in an area notorious for frigid, foggy summers was the only thing out of the ordinary that day. For Berkeley resident Lyrinda Snyderman and her kayaking buddies, it was nothing short of glorious.

Humpback whale lunge feeding in San Francisco Bay, July 10, 2016. Photo by Lyrinda Snyderman

As Snyderman paddled out past Angel Island, she noticed some odd, dark, triangular shapes appearing, then vanishing beneath the seabirds circling above the tideline. Tug boats, she thought. Then one of her friends yelled, “Whales!” Snyderman quickly switched her trusty camera to “zoom” and for the next 50 minutes, she and the kayakers had a front row seat to a pod of lunge-feeding humpbacks cavorting before their eyes. In the thirty years she’d been paddling around the Bay, Snyderman had never seen anything like it.

Humpbacks just don’t venture into the San Francisco Bay except for rare occasions when one is lost or sick and wanders in by accident. The appearance of healthy humpbacks in the Bay is extraordinary.

Dr. Jonathan Stern, a marine biologist at San Francisco State University, tracked the remarkable events last summer up close. “I would go out at the Marin Headlands between the Golden Gate and Land’s End. We would see 40 humpbacks at a time, spread out in groups just lunge-feeding. This was for weeks at a time.”

The unprecedented appearance of healthy humpbacks feeding in the Bay is a sign of complex shifts in climate and ocean ecology, marine biologist believe. Changing atmospheric conditions and water temperature, along with water quality, directly impacts where sea life lives and thrives.

“We tend to focus on the megafauna because we can see them,” Stern says. “But it’s important to focus on the little things, too. There have been these huge schools of anchovies right off shore, and as the tides move in and out of San Francisco Bay, so do the anchovies.”

And where the anchovies go, humpbacks follow.

Up until this year, Stern says, there were plenty of food resources for marine life further offshore around the Farallon Islands, 32 miles west of the Bay in the Pacific.

The anchovies, along with the rest of the food chain, have drifted from far offshore to exceptionally close to land this last year. What is propelling this change?

Just as humpback whales follow schools of anchovies, most sea life tends to follow cold, oxygen- and nutrient-rich waters that rise from the ocean’s depths. In normal years, the upwelling of deep, cold water rises out by the Farallon Islands. But this last year has been different.

Dr. Ellen Hines, associate director of Romberg Tiburon Center for Environmental Studies, explains that changing water temperature effects ocean circulatory dynamics, specifically Ekman transport.

Illustration by J. Chiappone

Ekman transport describes how winds blowing parallel to a coastline, together with the Coriolis effect of the Earth’s spin, cause ocean waters to circulate in a specific way. In the Northern Hemisphere, water moves 90º to the right of the direction of coastline winds. In California, this means warm surface waters move away from shore at a 90º angle from Northerly winds which blow in spring and summer. As warm surface water moves away from shore, deeper, colder water rises up in its place. The rise of deep, cold water to the surface is called upwelling.

Hines says where and when the upwelling occurs used to be predictable. However, a persistent ridge of high pressure, know variously as “The Blob” and the “Ridiculously Resistant Ridge,” set up over the North Pacific several years ago. The high pressure system held warm air in place, thus contributing to warmer than normal surface temperatures in the ocean below.

The Blob shouldn’t be confused with El Niño, though, which is warmer than normal water temperature arising along the equatorial Pacific. This year, both The Blob and El Niño were in full-swing, dealing the Western Pacific a double-whammy of warmer than normal water severely impacting where the deep, cold upwelling would be able to reach the surface.

Hines says, “The theory is that the upwelling is closer and closer to shore, restricted by this higher ocean temperature.” And as the cold water moves, so moves the food chain. “What is happening is that these animals are coming closer and closer to shore in search of food in the colder, more nutrient-rich waters.”

As you might imagine, the straits of the Golden Gate are bustling with ship traffic serving San Francisco, Oakland, and five other major ports on the Bay and in the Sacramento River delta. The Greater Farallons Marine Sanctuary estimates between 7,500 and 9,000 large ships transit the Golden Gate each year. These ships cut across marine habitats.

“As more animals come closer to shore, they’re in danger of ship collisions and…crab traps, which are what they really get entangled in,” Hines says.

There is also evidence that low-frequency noise from ships can be a stressor to whales, Dr. Maya Yamato, a marine biologist at Diablo Valley College says. Research shows that whales in the Northern Hemisphere have changed the frequency at which they communicate over the last thirty years. This could be an adaptation to the constant din of ships in their habitat.

But there are glimmers of progress in the protection of marine life and signs of improving water quality of the San Francisco Bay.

Dr. Jonathan Stern says, “Around the year 2000, the Bay started to become cleaner and more productive” thanks to decades of conservation legislation beginning to pay off.

“In 2008,” Stern says, “I followed a large school of porpoises inside the Bay, mothers and calves just cavorting around, and that was really surprising. Now, we see porpoises in the Bay every day. They actually come in with the tides and go out with the outgoing tides” following the small fish they feed on.

As many as 700 harbor porpoises now make the Bay part of their home, he says.

Interestingly, even if specific species of marine mammals are taken off the Endangered Species List, they’re still highly protected by the Marine Mammals Protection Act (MMPA).

Mary Jane Schramm of The Greater Farallons Marine Sanctuary says the MMPA  recommends whale observers stay at least 300 ft. away from marine mammals. Observers include windsurfers, kite boarders and boaters and is for the public’s safety as well as the whale’s.

“Stress from multiple non-lethal disturbances is also harmful, as (the whales) could be ‘spooked’ into heading…up the Sacramento River… There, death awaits if they don’t get back to the ocean,” Shramm says.

When recalling her experience kayaking near the humpbacks, Lyrinda Snyderman says, “To be in a small boat next to a whale, you really are sharing that environment with them. It was a privilege to be allowed into their lives.”

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