More than 40 miles out from the Golden Gate Bridge and over an undersea slope plunging from the edge of the continental shelf, a team of scientists lowered a specialized net into the cold, green Pacific Ocean.
Soon, the research vessel Fulmar, a 67-foot aluminum-hulled catamaran, began towing the net above the slope, known as the "shelf break," for a tiny but titanically important creature called krill.
Jaime Jahncke, director of marine ecology at Petaluma-based PRBO Conservation Science, already knew the catch would be slim.
"Honestly, right now there's not much of it here," Jahncke said last week aboard the Fulmar.
Echo soundings displayed on a screen inside the Fulmar's cabin showed a relatively small mass of krill, a transparent, shrimp-like crustacean, in the depths below.
Why the krill had cleared out wasn't clear, Jahncke said. And the meaning of the results on this particular day are neither good nor bad. But the consistent monitoring of the area enables scientists to assess patterns in the marine ecosystem, including possible impacts of climate change.
Last year, abundant krill drew record numbers of humpback and blue whales to the Farallones, and Cassin's Auklets, birds that dive 100 feet or more to catch krill, had unparalleled breeding success on the rocky islands.
Krill, found in all oceans of the world, are a cornerstone of the marine food chain. The half-inch long animals live in massive swarms, eating microscopic phytoplankton, and are, in turn, devoured by fish, seals, squid, penguins and even 40-ton whales.
Last week the scientists stationed on the Fulmar's top deck saw few birds or marine mammals in waters known as one of nature's most abundant pantries.
"There doesn't seem to be a lot of food," said Kirsten Lindquist, a field biologist with the Farallones Marine Sanctuary Association.
On a similar research cruise in July, the scientists came upon a "feeding frenzy," with about a dozen humpback whales, 4,700 birds, dolphins and sea lions roiling the ocean surface as they feasted on small Pacific mackerel.
The Farallones, a string of small, rocky islands barely visible from land on a clear day, play host to the largest seabird colony in the continental United States and are a key breeding ground for seals and sea lions.
Birds fly in from around the world — shearwaters from Chile and New Zealand; albatross from Hawaii — to feast in the surrounding waters from south of San Francisco up to Bodega Bay. About 50 bird species frequent the area, eating krill, scavenging on the ocean surface and diving for bait fish.
"It's a hot spot," Lindquist said. "One of the richest in the Pacific."
On last week's cruise, the scientists' best guess was that the whales and birds had moved on, possibly to the north, in search of more krill.
Nonetheless, they went about their chores on a daylong research cruise that departed from the Sausalito Marina shortly after 7 a.m. and motored west non-stop, bounding over the incoming swells for two and a half hours.
When there are no observers aboard, the scientists typically nap en route. They prefer working as the Fulmar returns eastbound, moving with the swells for a far smoother ride.
<NO1><NO><NO1><NO>The vessel cut to an idle over the shelf break at the west end of Line 6, a 26-mile east-west line running between the North and South Farallon Islands, within the Gulf of the Farallones National Marine Sanctuary.