For more than 45 years scientists from the Scripps Institution of Oceanography and the Southwest Fisheries Science Center have been studying the body of water that sweeps down the California coast. They are seeing changes — surface warming, population declines — that may be cause for alarm.
After 250 cruises in five decades, some 32,000 samplings, more than 90,000 hours of analysis, the California Current has become the most intensively studied large-scale ocean ecosystem in the world.
It was a lovely July night, with a star-filled sky, the sound of seals splashing in the harbor, and the occasional cries of pleasure from those fishing off the pier at Port San Luis, south of San Luis Obispo. Kenric Osgood and I were waiting for a ride out to the David Starr Jordan, a National Oceanic and Atmospheric Administration research ship. I had come along to meet scientists with CalCOFI — California Cooperative Fisheries Investigation. CalCOFI had recently received national attention following an article in Science magazine stating that zooplankton levels off Southern California had dropped by 80 percent in the past 40 years, possibly due to ocean warming.
Kenric Osgood was there to continue his study of one of those zooplankton organisms, calanus, the “sea cow,” which grazes on floating plant life and accumulated oils, and, small as a grain of rice, serves as an important food for many fish. Kenric was particularly interested in the 11th of 12 growth stages of calanus, and he would be using an optical particle counter to come up with numbers of calanus-sized animals in the waters off Santa Barbara.
Together we had spent six hours navigating the freeways from La Jolla through the metropolitan snarl to get to Port San Luis. When Kenric called the Jordan at 7:00 p.m., he was told the ship would arrive at 10:00, a three-hour wait that bothered him but didn’t bother me. I ate at Fat Cat’s, a diner-style restaurant by the parking lot, and would have eaten at the fancy place at the end of the pier if I’d had a chance. But then a Zodiac streamed in, two tousled-looking scientists disembarked, Kenric loaded his gear, we jumped aboard, and Chico Gomez, chief boatswain, raced off, circled the Jordan, and with a figure-eight flourish, pulled alongside. Kenric and I were helped up the ladder, the Zodiac was hauled aboard, and the Jordan headed back offshore.
The California Current is part of a huge clockwise flow of water that circulates through the North Pacific — westward through the equatorial Pacific, turning northward near the Philippines, bending eastward as it brushes by Japan and is pushed by prevailing winds along the west wind drift. Joined by subarctic currents, the stream divides as it nears Washington, one branch curling off into the Gulf of Alaska, the other branch, the California Current, flowing south before turning west again off the tip of Baja.
Like California the state, California the current is a vibrant mix of many origins — five, in fact: 1) waters from the west wind drift merge with 2) cool and nutrient-rich waters from the SubArctic Pacific, which join 3) warmer offshore waters coming from the west and 4) even warmer equatorial waters coming from the south by means of a countercurrent, all of which, as they move horizontally, are affected from below — vertically — by 5) highly fertile waters welling up from the deep.
The California Current is no Old Man River; the character of the water is complex and ephemeral. Narrow meanders switch back and forth at high speeds. Eddies and whirlpools spin like ball bearings, sending off “squirts” and “jets” and “filaments” that rapidly pull water away from shore. Temperature gradients pile up and tilt like tectonic plates. There are shifting density layers and salinity layers moving with the flow. These “thermoclines,” “pycnoclines,” and “haloclines” often act as fences and pathways for marine life.
All five sources of the California Current bring their various life forms, and these mix with species native to the California coast. The ecosystem that forms has been described in one Scripps bulletin as “a succulent seafood stew, with ingredients that vary according to Chef Neptune’s whim.”
Over the centuries, two predominant ingredients of the stew have been anchovies and sardines, vast schools of them feeding on the zooplankton and serving as important prey sources for larger fish, mammals, and birds — and in this century, commercial fisheries. Populations of sardines and anchovies have exploded and collapsed according to the natural ebb and flow. At about A.D. 575, the anchovy population in the southern California Current was 5 million metric tons (11 billion pounds) but then nearly disappeared shortly before 1300. Since 1970 populations have ranged between 1.6 and 0.3 million metric tons.
Sardines and anchovies have tended to alternate in abundance. In the 1940s, the sardine fishery in California was the largest fishery in the world until the population plummeted. Many thought the cause was overfishing, it seemed an obvious conclusion; but others, particularly those in the fishing industry, thought the cause might be natural, part of the ebb and flow. The California Department of Fish and Game recommended a closure, but fishermen appealed to the legislature for a tax, per ton of sardines, to finance scientific study of the fishery. Thus, CalCOFI was born.
The “Cooperative” part of CalCOFI is an important element of its success, as three agencies came together to do the work: Scripps Institution of Oceanography, the Bureau of Commercial Fisheries (later the Southwest Fisheries Science Center, an arm of the National Marine Fisheries Service), and the California Department of Fish and Game. (Recently the cooperation has extended worldwide, with the database accessible on the Internet.)
The scientists who organized CalCOFI knew that the issue was larger than sardines, that the problem was a multi-species one and linked to the environment in a broad way. It was a unique view in 1949. Those “visionary-type scientists” (according to John McGowan, a Scripps biologist who, as a graduate student, went on a CalCOFI cruise in 1951 and who coauthored the Science article) exploited the sardine fishery collapse, pursuing a vision for a big study of a big area, with monthly cruises sampling seawater at hundreds of stations. They did this for ten years, running three ships in zones from southern Baja to Oregon. But as time passed, costs increased and funding diminished, and CalCOFI eventually settled down to one ship, four cruises a year, with offshore stations from Del Mar to Purisma Point (south of Port San Luis), 40 miles apart on lines that run as much as 350 miles out to sea. In the process, the science of fisheries oceanography came into being.