A COMEBACK STORY: HARBOR PORPOISES RETURN TO THE BAY
Tiburon Peninsula researcher, Romberg preparing to publish new study on the marine mammals, which disappeared from the San Francisco Bay in the 1940s
Editor’s note: This story originally appeared in the Aug. 5, 2015, edition of The Ark. It earned second place for Best Environmental Feature Story in the National Newspaper Association’s 2016 Better Newspapers Contest and first place for Best Environmental Reporting in the California Newspaper Publishers Association’s 2015 Better Newspapers Contest.
By GRETCHEN LANG
glang@thearknewspaper.com
When Milt McDonogh was a young man growing up in the 1920s, he could hear harbor porpoises blowing off Elephant Rock at night as he lay in bed. He could watch them play in Racoon Strait as he piloted his ferry from Tiburon to Angel Island. But by the time his daughter, Maggie, took over as captain of the Angel Island-Tiburon Ferry, the harbor porpoises were long gone from San Francisco Bay.
Those were the years when the bay was fouled by pollution, construction and fill. Large marine life largely disappeared from bay waters.
But in 2007, something remarkable happened. Scientists out on a scouting cruise spotted a small group of what looked like porpoises, the first seen in the bay in 65 years.
“I was really excited,” says researcher Bill Keener of East Corte Madera, who recalls glimpsing his first porpoise from the hills of Sausalito. “But I thought this is a rare thing, it won’t last.”
But it did last and today, Keener and a group of marine biologists based at San Francisco State University’s Romberg Tiburon Center for Environmental Studies are preparing to publish their investigations into a remarkable comeback story — the return of the harbor porpoise to San Francisco Bay.
Harbor porpoises, Phocoena phocoena, are among the smallest members of the cetacean family, which includes dolphins and whales. Weighing about 100–150 pounds and measuring up to 6 feet in length, they roam temperate oceans of the north Pacific and Atlantic oceans and the Black Sea. Because they are small and dark and do not rise very high out of the water when swimming, it can be hard to spot them from shore, but Bay Area scientists have discovered a unique platform from which to observe them: the Golden Gate Bridge.
In 2010 Keener, an environmental lawyer and former executive director of the Marine Mammal Center, created Golden Gate Cetacean Research with the help of Jon Stern, a marine biologist at San Francisco State University, along with other marine biologists there and graduate researchers based at the Romberg center. All of them are unpaid volunteers.
The nonprofit studies porpoises, dolphins and whales along the Northern California coast and in San Francisco Bay.
With some backing from the National Wildlife Federation, Cetacean Research is now studying various aspects of porpoise behavior from the bridge and the hills above the Golden Gate, and together they launched the “Return of the Porpoise to the San Francisco Bay” campaign, at sfbayporpoises.org, to accept sighting reports and donations for research.
So far, Cetacean Research has photographed and catalogued more than 600 individual porpoises as they commute back and forth under the bridge, Keener says. Some have unusual scars that make them easy to track. There’s even a pure white one.
Up to now, most of what we know of porpoises has come from studying their carcasses, Keener says. Using high-powered cameras, scientists can now observe these elusive animals from the deck of the bridge.
“Nobody has been able to spend time looking at their behavior before,” he says. “That’s what makes our studies unique. We are witnessing their social life.”
But why have the harbor porpoises returned to the bay after all these years? What drove them away to begin with?
Scientists say the trouble probably started in the 1930s with large construction projects that included the Golden Gate and Bay bridges; porpoises are sensitive to noise and were likely driven from the area. Then came World War II and the installation of 7,000-ton, 7-mile-long anti-submarine net across the Golden Gate strait. The net was constructed at the U.S. Naval Net Depot in Tiburon, where the Romberg center is now, and was only removed after the war.
Scientists agree that it has taken many years to set the stage for the porpoises return.
Keener says he remembers when the water of the bay was so polluted with raw sewage and industrial waste that you could smell it coming over the Richmond-San Rafael Bridge. Efforts to restore the bay to its former health have taken generations.
“(The porpoises) didn’t just magically reappear,” Keener says. “The Clean Water Act, restoration efforts — all these things have had a positive impact.”
In the end, the porpoises are here because their prey is here. Large schools of anchovies and herring thriving in the cleaner waters have tempted them inside the Golden Gate, says Laura Duffy, a San Francisco State graduate student in marine biology and one of two young Romberg-based scientists working with the Cetacean Research group.
She is studying how porpoises feed and congregate according to the tides in the bay.
“It looks like the ecosystem is actively improving,” Duffy says. “The porpoises wouldn’t be hanging out here if it wasn’t a reliable place for food.”
So reliable in fact that scientists have witnessed up to 66 individuals coming through the Golden Gate in as little as 30 minutes.
“It’s like rush-hour traffic,” Duffy says.
Duffy hypothesizes that it’s the tide that is ringing the dinner bell for these animals. They seem to be timing their movements to the changing of the tides, when fish gather in the turbulent waters of a tidal front to feed on stirred up plankton.
Porpoises, she says, may have some kind of internal clock linked to the tides or might be judging their environment by the water quality and movement, deciphering when the tide is getting ready to turn.
Knowing where and when porpoises congregate in the bay will help protect them from encounters with marine traffic, she says, now that this federally protected species has moved into urban waters.
Duffy, who studies wildlife as a “living indicator” of what is happening in the environment, says the return of harbor porpoises and other top predators — like seals, otters, dolphins and sharks — is a hopeful sign that the hard work of conservationists is paying off.
“Cleaner water has given us a chance for higher productivity, and now you’re seeing the ecosystem that can support top predators,” she says. “It’s a sign of an ecosystem on the mend.”
And that means that Milt McDonogh’s children and grandchildren now experience the bay as he once knew it. Maggie McDonogh says she now sees porpoises almost daily in Racoon Straight as she makes her dad’s old run to Angel Island from Tiburon. Not long back, she says, she even saw a mom and calf.
“It’s wonderful,” she says. “The bay is a magical place.”
Contributing writer Gretchen Lang of Belvedere covers the environment. She spent 15 years abroad writing for newspapers including the Boston Globe and the International Herald Tribune.
