Harbor porpoises as seen from the Golden Gate Bridge. (Photo: William Keener/Golden Gate Cetacean Research)

Harbor porpoises haven't been seen in San Francisco Bay for more than 60 years. But now, they're coming back through the Golden Gate in growing numbers and researchers are trying to understand why they’re returning.

The best place to look for them is 220 feet above the water on the pedestrian walkway across the Golden Gate Bridge. That's where Bill Keener of Golden Gate Cetacean Research photographs them, holding a massive telephoto lens over the side of the railing.

"There's a porpoise right there, coming very, very close," he says pointing. A dark shape appears in the water. It's a harbor porpoise, coming up for air. "And here's a mother and calf coming straight at us."

The porpoises have dark gray backs and pale bellies. They're about five feet long, smaller than most of their dolphin relatives.

"Look at that! That one's on its side," Keener says. "The porpoise turned on its side. It's spinning and it's feeding."

Porpoises spin as they go after schools of herring and anchovies, which means these porpoises are feeding in the middle of a heavily-trafficked shipping lane. "The porpoises have found a way to not only avoid the ships, but it's also the noise they make," says Keener.

Studying a Shy Marine Mammal

Seeing this behavior is huge for Keener. Harbor porpoises are notoriously shy in the open ocean, so they're tough for researchers to study. Here in the bay, Keener and his colleagues have identified 250 individual porpoises with their photos by looking for unique scars and color patterns on the animals.

Porpoise mating display as seen from the bridge. (Photo: William Keener/Golden Gate Cetacean Research)

When these researchers first started their work on the bridge, they caused a bit of a stir. "You noticed there was a Golden Gate Bridge patrol officer here just a few minutes ago," says Keener. "Well, we're staring down at the water for hours. They'd start getting worried about us. But they know us now. They know what we're doing."

Of course, the big question is why harbor porpoises disappeared in the first place. Keener says the bay has historically been porpoise habitat. Their bones have been found from hundreds of years ago.

"And then there were reports in the 1930s. And then we don't really have reports from around World War II. And there were a lot of things going on during World War II that could have caused that."

San Francisco Bay became a wartime port and a major ship-building center. The Navy strung a seven-mile-long net underwater across the opening of the bay to keep out Japanese submarines. Hundreds of mines were planted in the waters outside the Golden Gate.

Keener says all that activity certainly would have disturbed the porpoises. But there's a bigger change that may have driven them away.

The Changing Bay

To see it, we head toward the Golden Gate Bridge on a twenty-two foot boat with Jonathan Stern, a whale researcher at San Francisco State University. Stern was the first person to spot the porpoises in the bay three years ago.

"I just couldn't figure out what they were doing here. It's like when you see somebody you're used to seeing at work and you see them somewhere, in Hawaii or something. What are you doing here? You're out of place," says Stern.

The bay we're gliding over today is a far cry from the bay in the 1950s and 60s. As the Bay Area boomed, so did water pollution. Keener says raw sewage used to flow right into the bay. "I remember coming across the Bay Bridge when I was very young and it would just smell. It would stink."

After the Clean Water Act was passed in 1972, the bay's water quality began to improve. But Stern says it took time for the food web to come back. "It takes the biology a while to track the chemistry. So it's not surprising that it's taken years for this ecosystem to generate like this."

Stern says it's also possible that the porpoises had to rediscover the bay. "Because over 60 years, we're talking about a number of generations of porpoises. So it's quite likely that San Francisco Bay as a location, as a habitat was out of the institutional memory of the harbor porpoises off the coast here."

Bill Keener and Jonathan Stern search for porpoises in the bay.

As we slow down under the bridge's span, Keener keeps an eye out. "There are porpoises between us and the south tower at 200 yards," he says.

Keener and Stern have a special permit that allows them to approach the porpoises. We wait, listening for them to surface.

"I just heard one here. Here's a cow-calf pair close to the boat and we'll hear this puff," Keener says.

We hear two loud puffs as the porpoises surface just off the bow. "The old time sailors used to call them puffing pigs. That's the exhalation," says Keener.

The harbor porpoises seem calm around boats in the bay, which Stern says will let researchers study their life cycle and social structure, as well as how they might react to big events like the upcoming America's Cup race. Overall, he says it's a good sign that the porpoises are here.

"It's one of those very few good news environmental stories. And it's in our backyard. You know, there was the will to get the bay cleaner and we're now starting to see the effects of that. It gives one hope."

Trash in the Los Angeles River, en route to the ocean. Photo: kqedquest.

Plastic bottles, aluminum cans, plastic knives and forks, tangled fishing line, plastic bags, food wrappers, cigarette butts… all this and more will be collected from California’s beaches this coming Saturday, September 25, on Coastal Cleanup Day.  On last year’s Coastal Cleanup Day, volunteers collected over 1.4 million pounds of trash from California’s beaches and waterways. That is a mind-blowing amount of trash!

All this trash has a devastating effect on ocean life. Sea turtles eat plastic bags, mistaking them for jellyfish. Marine mammals get tangled in abandoned fishing nets. Sea birds are found with bellies full of colorful plastic shards. And, plastics can leach chemicals into ocean water. Bisphenol A, the chemical in hard plastic water bottles, has been found in seawater. Bisphenol A and other chemicals can mimic animals’ hormones and disturb their development. It can also bioaccumulate in fish and shellfish—and could potentially end up on our dinner plates.

The trash that washes up on our beaches is only a tiny fraction of the debris in the ocean. Check out QUEST’s TV Story, Plastic in the Pacific, to get a sense of the Pacific Ocean Garbage Patch. This collection of trash, caught in a gyre in the middle of the Pacific Ocean, is perhaps twice the size of Texas. It isn’t just floating plastic water bottles—it’s also a soup of tiny, confetti-like fragments of plastics that have started to break down, but will never completely disappear.

Coastal Cleanup Day is a great opportunity to clean up California’s coasts and prevent this trash from getting swept out to sea. It also sends a message: people care about minimizing the impact of trash on the environment. Last year, over 80,000 people volunteered on Coastal Cleanup Day. To find locations where you can volunteer this Saturday morning, look here.

Ultimately, we need to decrease the amount of trash we produce. In Germany, a policy was put in place in 1991 that made manufacturers and stores responsible for recycling all the packaging material for the products they make and sell. Customers unwrapped their purchases at the checkout stand and left all the wrappers at the store. (My dad tried this at home in Virginia—it didn’t go over so well.) This forced German manufacturers and retailers to create a recycling program to deal with all the trash, and provided a strong incentive to reduce the amount of packaging they used in the first place. A few California cities are off to a good start with localized bans on plastic bags. Let’s come up with other ways to ensure that in the coming years, volunteers on Coastal Cleanup Day will have less work to do!

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Each year the Marine Mammal Center treats somewhere between 600-1000 animals, including California sea lions, Pacific harbor seals, Northern elephant seals, and steller sea lions. About half of them are treated successfully at the center and released into the Pacific. The other half either die naturally or have to be euthanized.

Most of them end up at the center's hospital after passersby spot the animals on the beach and sense something’s wrong. (The Marine Mammal center responds to calls anywhere between Mendocino and San Louis Obispo Counties — some 600 miles of coastline.) Some problems are human-caused, like boat-propeller injuries or ingested fishing nets and hooks. Other times, it's cancer, domoic acid poisoning, or leptospirosis. Sometimes, it's hard to tell exactly what happened — hence the need for necropsies.

On the day that Quest intern Jennifer Skene and I visited the center, veterinarian Nicola Pussini performed two necropsies, both on sea lions. One animal seemed to have died from a tumor underneath his fin; the other was a suspected domoic acid intoxication.

Each necropsy takes about an hour and a half. First Pussini measures the animal, then he slices it open and inspects every part, from tongue to tail. He inspects the teeth, pulls out all the organs, checks to see how much fat the animal has. The data, along with tissue samples, are archived and shared with other research institutions. This is the kind of basic research that Marine Mammal Center staff cite when people ask why they devote so many resources (most of it from private donations) to animals whose populations are neither threatened nor endangered.

I should mention that I didn't exactly see this entire process firsthand. Let's just say that after my first strong whiff of sea lion intestine, I felt a compelling need to go check on things outside the necropsy room. Luckily for me, Jennifer has the stomach of a true scientist and managed to both hold the microphone and take photos. Luckily for you, we’re sparing you her gorier shots.

Listen to the Sea Lion Rescue radio report online, and watch our photo slideshow.

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