San Francisco's Pier 39 is home to only a few sea lions this summer.

I spent Saturday sightseeing in San Francisco with a friend visiting from out of town, and I thought I’d check in on the sea lions at Pier 39. Just a few years ago, there were about 1600 of them, slithering on and off the wooden docks, basking in the sun, and barking at one another. Then in 2009, most of them swam away, as QUEST blogger Amy Gotliffe explained. The sea lions’ favorite food, herring, was in short supply, so they went to Oregon to feast on anchovies and salmon. Now the herring are making a comeback—will the sea lions return too?

This weekend the floating wooden palates at Pier 39 were mostly bare; there were perhaps a dozen sea lions. We would expect the sea lion numbers to be low this time of year, herring or no herring. In the summer, sea lions travel down south (the Channel Islands, San Diego, Baja) to breed. But there were still fewer sea lions at Pier 39 than in summers past.

Sea lions will eat a lot of different prey items: octopus, squid, small sharks. But their bread and butter is herring, which have been hard to find in recent years. The herring fishery is the only fishery still in operation in San Francisco Bay, and it closed during the 2009/2010 season (December through April), because there were so few fish. This year, the herring fishery opened again, but with a lower quota than in the past, to allow the fish to recover.

There are a few hypotheses about why the herring numbers dipped so low in 2009. First, herring lay their eggs in the brackish waters of the estuaries around San Francisco Bay. Each female fish can lay up to 50,000 eggs, which are a prized commodity in Japan. However, the years leading up to 2009 were drought years, so the estuaries were saltier than usual. That may have affected the herrings’ spawning success. Second, the 2007 Cosco Busan oil spill may have affected herring health. Researchers found oil-soaked embryos, which were deformed. Third, herring declines may be the result of climate change. As surface waters get warmer, there is less mixing with cold, nutrient-rich water from the bottom of the ocean. There are also big patches of the ocean that have very little oxygen. These hypoxic zones are deadly to their inhabitants, and are affecting many marine species.

However, the herring appear to be making a comeback, possibly because the past few years have been wet and the estuaries are sufficiently fresh, or because the spilled oil has been flushed from the Bay. Time will tell whether the sea lions follow their food and return to Pier 39. I hope they come back—along with the twists and turns of Lombard Street and the Golden Gate Bridge, the Embarcadero’s sea lions are one of my favorite San Francisco treasures to show off to visiting friends.

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Humboldt Squid. Photo: NOAA/CBNMS.

Large numbers of Humboldt squid, deep purple-red and up to six feet long, have propelled themselves into Monterey Bay mid-summer since 2002. They spend the fall and early winter here, probably to feed, and then spend spring further south. But this year, the squid have yet to arrive. No one knows if the squid are behind schedule or if they’re not going to show up at all. Humboldt squid isn’t the most popular item on the menu in North America, but it is very big in Japan, making it the world’s 14^th largest fishery by weight. And, their absence leaves a hole in Monterey Bay’s food chain. The Humboldt squid are voracious predators, feeding on anchovies, sardines, rockfish, market squid, and crustaceans. The delayed arrival of the Humboldt squid is a mystery, and it could have consequences for the underwater ecosystem—in Monterey Bay and all along the coast of California.

Humboldt squid haven’t been in our waters forever. Check out QUEST’s TV story The Fierce Humboldt Squid for the full story. Historically, the Humboldt Squid have lived in equatorial waters of the Pacific, from Chile to Mexico. In the 1930s, their range extended further north, and they were caught by fishermen in Monterey. Then they disappeared, only to return briefly in 1997. But they returned again in 2002, and have every year since.

There are a few hypotheses about why the squid come and go. Maybe they are responding to changes in their food supply. Or, their populations may grow when there are fewer predators—Humboldt squid are eaten by tunas, sharks, and sperm whales, some of which are in decline. Another possibility is the warming of northern waters, caused by El Niño. Trade winds usually blow from east to west across the Pacific, piling up warm water near Indonesia. During an El Niño, the trade winds die down, and warm water moves eastward, towards North and South America. The typically cold waters of Monterey Bay become unusually warm—warm enough, scientists think, for the Humboldt Squid to move in. The squids returned in 1997 and again in 2002—both were El Niño years. After 2002, the warm El Niño waters didn’t stick around, but the Humboldt squid kept coming back. This year, the squid are absent, and this is surprising because it seems to be an El Niño year (remember all that rain we got this past winter?).

Julie Stewart, a grad student at Stanford’s Hopkins Marine Station, is researching the migration and movement of Humboldt squid for her dissertation. (Her advisor, Professor William Gilly, is featured in the QUEST video.) Julie has data from thousands of hours of underwater video, filmed on MBARI’s submersibles, which she’s using to estimate squid populations over the past decade. She’s put satellite tags on squid, to see where they go and how deep they dive. She wants to find out whether the squids' movement is in response to food supply, predators, ocean conditions, or other variables.

Julie wondered if the squid were here, but in small numbers, making them harder to find. Or, if the squid were just very far offshore. So last week, she spent five days aboard a Monterey Bay National Marine Sanctuary research cruise, looking for squid. The primary purpose of the trip was to do marine mammal and seabird surveys, which happen during the daytime—the captain let her search for squid at night. Julie and other crew on the boat used jigs—glow-in-the dark lures with spikes—on fishing lines. They jigged at 10 stations near the Davidson Seamount, about 80 miles southwest of Monterey Bay. And they found exactly zero squid. Even far offshore, the squid were nowhere to be seen. Julie and her colleagues have been talking to fishermen up and down the west coast, from southern California to Washington, and no one has seen squid this summer.

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Quest Educational Resources

 Print Guide - Muir Woods National Monument

 Muir Woods National Monument KML File

 Tips to get the kids in your life out into nature

 Designing an Exploration on Google Maps

Additional Links

• Redwood Transect Kit for Educators

This sushi is good enough to eat.
Photo credit: Andrea Kissack.

There is a new trend in town. Sustainable sushi. The Monterey Bay Aquarium, and two other ocean conservation groups (Blue Ocean Institute and Environmental Defense Fund), have come out with new advice for making better sushi choices. Modeled after the Monterey Bay Aquarium’s popular Seafood Watch Pocket Guide, the new sustainable sushi guide helps consumers make informed choices by categorizing seafood into three areas: Green (or best choice), Yellow (or good alternative) and Red (what to avoid). Just what kind of sushi you should avoid may surprise you. Until now, Unagi (bbq eel with avocado), seemed pretty harmless and a good choice for reluctant sushi eaters. Well, Unagi is farmed, freshwater juvenile eel so that definitely gets a red light from the Seafood Watch folks. You can try a sustainable alternative to Unagi at Tataki Sushi Bar in San Francisco. It may be the only restaurant of it’s kind in the country. The owners of the all sustainable sushi restaurant say they don’t want to become a niche as much as they want to influence the rest of the industry to change its’ practices. And with sushi a growing multibillion dollar industry, consumer preferences can have a big impact.

So how do you green your sushi? Try Pacific Halibut, farmed scallop or North American Albacore. Monterey Bay Aquarium biologists consider these among the “best” seafood because they come from abundant, well-managed fisheries or are raised using sustainable aquaculture methods.

Image Source: Adactio

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