You have just imagined yourself onto Cordell Bank, 18 nautical miles (about 20 statute miles) west of the Point Reyes lighthouse: an extraordinarily rich marine environment in which countless species of invertebrates, fish, birds, and marine mammals feed, breed, and flourish. So valuable is this geologic feature—a sort of Yosemite of the deep—that in 1989 it was designated the sixth national marine sanctuary, joining the Gulf of the Farallones and the Channel Islands as California’s representatives in the system (Monterey Bay was added three years later). Encompassing 526 square miles on the surface, the sanctuary boundary starts six miles off Point Reyes. Underwater, it takes in the “island” of Cordell Bank, which measures 4.5 miles wide by 9.5 miles long at the base and tapers to “hip”-straddling reefs some 165 feet deep and a series of flat-topped plateaus.

Those few who know the place describe an environment beyond belief, as rich in species diversity and abundance as a tropical reef. Yet for most of us, it must forever remain a place of the imagination. SCUBA diving isn’t really a possibility. “Besides white sharks, cold water, lack of light, and lack of time at the bottom,” explained Ed Ueber, manager of the Gulf of the Farallones Sanctuary, “the current is so strong that you could wind up five miles away from the boat.” And that, as they say, would be that.

How, then, do we know what’s down there? For that matter, how did we figure out that there was anything down there in the first place? And who was Cordell, anyway?

An Open-Ocean Shoal

For the answers to those questions, we must go back to 1850. The granting of statehood to California brought a flurry of fact-finding missions as the government sought to ascertain just what it had acquired. One such undertaking was a survey of the coast to ensure maritime safety, carried out by the U.S. Coast Survey. Among those in charge of the hydrography was George Davidson. On the night of October 20, 1853, Davidson was proceeding south along the coast when he was enveloped in dense fog. Wishing to determine his position, he dropped a lead line overboard and found himself in a mere 30 fathoms (180 feet) of water: less than half the depth he expected over the continental shelf. He surmised—correctly—that he had discovered a rocky bank, which he placed—also correctly—23 miles west of the Pt. Reyes head.

Now skip forward in time, to after the Civil War. In late 1868 Davidson became aware of mariners’ reports of a “shoal west of Pt. Reyes.” By this time, Edward Cordell, a German-born surveyor who had aided the Union navy by surveying harbors essential for replenishing supplies, had been appointed assistant to the superintendent of the Coast Survey and sent to California. Davidson suggested to Cordell that he search for the reported shoal. Cordell did so, at first without success, but finally his diligence paid off: in June 1869, attracted by large numbers of birds and mammals, indicating abundant food, he located the bank. Six months later, Cordell died of an accidental fall, an unfortunate event that nevertheless assured his place in the list of California place-names.

Cordell was the first to collect samples of the life of the bank: eight vials’ worth, which he described as “red, slimy masses,” while the bank itself he characterized simply as “rocky, with live barnacles.” Although several more hydrographic surveys were conducted over the ensuing decades, no significant research was done until 1949, and that was largely geological in focus. The most extensive study of the bank’s living organisms, lasting ten years, was initiated in the late 1970s by Robert Schmieder of Cordell Expeditions, a nonprofit research group based in Walnut Creek. “Using air scuba, volunteers, and the optimism of inexperience, the first scientific dive on Cordell Bank was made on October 20, 1978,” Schmieder wrote in his 1991 book, Ecology of an Underwater Island. “The sight we beheld that day was breathtaking: visibility greater than 25 m, jagged rocky outcrops with a dense and lavishly colored invertebrate and algal community, and a myriad of large rockfish circulating slowly overhead. A single glance was enough to convince even the most skeptical that this was truly an extraordinary place.” Dives were short—about 15 minutes in duration—and divers oriented themselves by lines attached to buoys floating on the surface and snagged on the reef by anchors.

More recently, the sanctuary has been conducting an ecosystem dynamics study both on the surface and beneath the swells. Water samples taken at several depths both day and night suggest just how bustling this area of the ocean is. In the surface layer alone, said Sanctuary Manager Dan Howard, “It’s fascinating what you see. Krill can travel from below 200 meters up into that surface layer in little more than an hour. Juvenile rockfish, juvenile dungeness crabs, krill, copepods, salps, ctenophores, siphonophores, and myctophids [a deepwater group of fish commonly known as lanternfishes]: they’re all there.” And then there’s the stuff that makes all of this zooplankton possible in the first place: microscopic plant life, which is measured by analyzing the water for chlorophyll content.

Perhaps the most exciting work is going on below the surface. After having some success with remotely operated vehicle surveys, two years ago the sanctuary contracted the use of the two-person Delta submersible. As Ueber observed, to be at such depths is “incredible: it opens up a window into a world that almost no one has seen. I bet you there aren’t 50 people who have seen what people on these expeditions have seen. There are more people who get to the top of Everest every year.”

And what they have found truly is incredible. Vast numbers of rockfish at various life stages, especially widows, yellowtails, and blues, which tend to school in midwater, and some deeper-water species such as yelloweyes, canaries, vermilions, and bocaccios, which are not typically seen near shore. Traveling through an aggregation of 700 fish was not unusual. Indeed, Ueber said, “At times you couldn’t see 10 feet because of the concentrations of small fish. And we saw animals down there schooling that we didn’t know schooled. Spotted ratfish, for example: we estimated 250 of them in one school, and there were probably a lot more than that that we just couldn’t see.”

The Food Web Stops Here

What makes for this abundance, this diversity? In a word or two: geology and oceanography. “The Sonoma/Mendocino coasts,” explains Howard, “have some of the strongest upwelling in the world. This produces incredible productivity north of the bank, and when the current flows southward, the plankton that thrive on the nutrients brought to the surface flow over the bank and wash bank residents with food.” [For an explanation of upwelling, see Coast & Ocean, Summer 1998.] Sanctuary biologists are trying to find out if a local eddy exists over the bank during upwelling. If so, this eddy could retain food and increase feeding opportunities for bank residents. And then the larger animals come: black-footed albatross swoop 3,000 miles from their nesting grounds in the Northwest Hawaiian Islands, several times a year, just to nibble at this delectable buffet, and baleen whales regularly stop here during the summer months to feed. These animals eat at many trophic levels. Blue whales and gulls, for instance, dine on krill, and humpbacks and puffins prefer fish. Meanwhile juvenile and adult rockfish—some forty species in all, ranging in adult size from the eight-inch pygmy to the three-foot yelloweye—can be found up and down the water column, benefiting from this soup as well. They are joined by many other fish, including lingcod, flatfish, little reef-flitting greenlings and sculpins, rays, and sharks. And interestingly, several animals that are normally considered strictly intertidal (living on relatively shallow, nearshore rocks) can be found on Cordell Bank, including the red-striped acorn barnacle, a turban snail, and a kelp—again bespeaking the unique living conditions that the Bank provides.

For those of us not lucky enough to have access to a submersible, there is still plenty to see on the surface. The Oceanic Society offers trips to both the Farallones and, less frequently, to Cordell Bank (visit their web site for information: www.oceanic-society.org/index5.html). Also, Point Reyes Field Seminars offers wildlife watching boat trips to Cordell Bank (www.ptreyes.org/field/fsnat.html). If you’re a birder on these trips, you can add a number of open-ocean birds to your life list: albatrosses, shearwaters, storm petrels, puffins, auklets, murrelets, phalaropes, terns, jaegers, and skuas. And very rarely an endangered short-tailed albatross skids in for a snack, causing birders’ boats to list dramatically. Twenty-six species of marine mammals are known to occur in the waters around Cordell Bank, including gray, blue, humpback, minke, fin, and sei whales, Pacific white-sided dolphins, and various pinnipeds. Occasionally an ocean sunfish or sea turtle will lumber into view. Sport fishers, too, visit the area, despite rough seas and unpredictable weather; their main catches now are albacore and salmon. (Rockfish are currently off-limits due to a federal moratorium on groundfish that restricts fishing between 20 and 120 fathoms.

If you are prone to seasickness, you can visit the sanctuary website (http://cordellbank.noaa.gov) or visit land-based visitor centers to learn about the sanctuary. The Crissy Field Coast Guard station has a Cordell Bank display, and within two years there should be a display in the Bear Valley Visitor Center at Pt. Reyes National Seashore and possibly in Bodega Bay (the launching point for natural history excursions to the Bank).

The depth, distance from shore, and roughness of the seas around Cordell Bank make it a place that few of us will experience first-hand. “This is the one sanctuary where important ecosystem research can be carried out because you remove the effects of man,” said Ueber, who until recently was also manager of the Cordell Bank Sanctuary. Though, as always where humans are concerned, that statement needs to be qualified, for of course, evidence of human activity can be found even here. Lost longlines, gill nets, and trawl cables sparsely litter the Bank. And as Ueber pointed out, although the numbers of rockfish seen today are impressive, “It’s hard to judge the numbers without historical background: it seems like a lot, but it could be but a fraction of what there was.”

The sanctuary’s job is to safeguard this precious resource for the future, and the Bank’s remoteness does help. Right now a review of the management plan is in process, said Howard, to chart a course for the next five years as regards research, education, outreach, resource protection, and other matters. The documenting of habitat types, species makeup of the invertebrates and algal turf, determining fish abundance and distribution, and describing planktonic communities will increase our knowledge of this exquisitely productive area. This knowledge can then be used to further protect and better manage this unique marine area known as Cordell Bank National Marine Sanctuary.

Anne Canright is associate editor of Coast & Ocean.