What the health of whales and porpoises can tell us about the health of our bay and ocean
Marine biologist Jon Stern studies cetaceans: porpoises, dolphins and whales. Stern is a professor at San Francisco State and also leads field studies on the Northern California coast for the non-profit Golden Gate Cetacean Research. So he’s gotten up close and personal with his fair share of dead whales.
As a biologist he’s performed plenty of necropsies -- examining an animal and getting tissue samples after its death -- like a big blue whale that washed up on San Francisco’s Ocean Beach in the 80s.
“Typically when we necropsy whales, we cut them open and there’s a lot of internal organs, and there’s blood on the beach…” Stern says.
But because this whale ended up on Ocean Beach, which has a steady stream of visitors, Stern and his three researchers needed to do their work with a minimum of mess. So they carefully cut three slices through the blubber of the whale.
“And we pulled the blubber up over the top of the whale using ropes.”
They fastened the ropes into the sand, and Stern crawled inside with a knife and a flashlight to start getting the tissue samples he needed.
But then something weird happened. The flab of blubber fell over, closing Stern inside the whale.
“And the only thing I could hear was the sound of laughter from my three friends who were outside of the whale.”
Stern started panicking
“It was getting dark outside and I was afraid the tide was going come in, and I was afraid my friends were going to leave me. The fears start running through your head.”
Finally, the others managed to pull back the blubber, and Stern crawled out. He had to throw his clothes away after that.
When Stern isn’t escaping from the inside of whales, he’s studying them. He’s a world famous expert on minke whales. He gives names to the ones he tracks, like “Linda Ronstadt” in Monterey Bay or “Johnny Rotten” in Washington state.
But it was an unnamed whale that first got him interested in the species, when he was just eight years old.
“My dad was a ship’s captain ... he was away and I was home alone watching the news. They broke into The Beverly Hillbillies to report that a ship out of San Francisco was struck and disabled by a whale...and it was my dad’s ship. I knew it was huge, but the idea that something could hit a ship and disable it was just fascinating to me.”
That whale was killed, like many others who hit, or get hit by ships. The most recent dead whale that was found in Alameda was struck by a ship. Right now Stern is working on a computer model that simulates whale behavior and ship traffic, to try to decrease the amount of these collisions. As for the increase in dead whales that have washed ashore in the past few months, Stern says there’s not really a clear reason. It could be a function of ocean currents and wind pattern.
“It’s not unusual that that many whales die...it’s unusual that that many whales watch up on beaches where people see them,” he says.
Five to ten percent of the whale population dies every year.
“I mean that’s just a fact of life. Most of them, when they die, they quite likely sink to the bottom of the ocean where they provide a really neat ecosystem for these creatures that live down there.”
But there could be more serious things going on, too. One possibility is a huge bloom of toxic algae that stretches from California to Alaska. Since May, 30 dead whales have been found in the Gulf of Alaska. While marine mammals might not eat the algae directly, they can die if they eat smaller organisms that have ingested it. Blooms of algae are usually caused by high ocean temperatures. And right now, the Pacific ocean is really warm -- five degrees warmer than average.
“This is looking to be like a major El Niño forming this year, but there’s also this weird anomaly in the North Pacific...its called the blob,” he says.
Yes, that’s what scientists call it: the blob. It’s a big puddle of super warm water extending up into the Gulf of Alaska. Scientists don’t know for sure what’s causing it, but some believe the blob is an effect of climate change.
“Water can take up a lot of heat without changing temperature, so for water to change temperature to get warmer it has to have absorbed a lot of heat,” Stern says.
But even with this big hot blob of water sitting along the coast, there’s still cold water even closer to shore. That cold water is caused by something called upwelling. When the wind blows offshore...
“The surface of the ocean is going offshore and that water has to be replaced by something. So it’s replaced by cold, nutrient-rich water from deep in the ocean.”
Anchovies love this nutrient-rich water, which means anchovy-eating whales, dolphins, and porpoises come closer to the shore. Upwelling has been strong recently and it’s one reason why surfers, swimmers, and boaters are seeing more marine mammals when they’re out on the water.
This is happening on the coast, but also inside the Bay, which is where Stern goes every month to photograph and count harbor porpoises. Sometimes he goes out in a boat, but today he’s observing from the shore in Sausalito.
While tourists snap photos of the Golden Gate bridge, Stern stands in the wind, underneath the bridge, pointing his camera down at the water below.
“These porpoises are in the foreground, and San Francisco is in the background. That’s just so cool.”
He’ll compare photos from today to others in a database to see if the porpoises are ones they’ve identified previously or are new visitors to San Francisco Bay.
The Bay is full of porpoises. Stern says he once saw a school of 25, and he’s counted up to 100 in an hour. This is really big news. From the 1940s until the early 2000s, porpoises didn’t come inside the Golden Gate at all, mainly because of an underwater net that was put up under the bridge during World War II to prevent submarine attacks. The bay also used to be extremely dirty. So Stern says it’s a good sign the porpoises are back.
“It's an indication that the coastal waters and San Francisco Bay are more productive,” he says.
The Bay and the coastal ocean are connected, which is why Stern thinks it’s just as important to study and record sightings of porpoises frolicking in the Bay’s currents as it is to note the dead whales that wash up this year. He says we can look at large animals like whales as barometers of the ecologies they live in.
“We have to use animals like whales and birds as proxies simply because they are so big. When there’s a die-off event, you can’t miss it.”
And Stern says this is kind of a big deal.
“We should be concerned about that because this is our backyard. What goes on in our coastal waters affects us, what goes on in the Bay affects us.”
Stern’s research shows how the ocean connects us all, from the smallest algae to the largest whale.