PRBO biologists and volunteers have been on the front lines of marine oil spill response for over a quarter-century. The ecologically rich waters of Central California, heavily traveled by freighter and oil tanker vessels, have been subject to numerous catastrophic accidents, with oil slicks fouling the ocean and beaches, damaging estuaries, and threatening seabird rookeries. In the immediate aftermath of a spill, many of us have taken to the field to survey stretches of coast and count and help rescue oiled birds.
|After the Cosco Busan spill, Gary Page recovers an oiled Western Grebe from an ocean beach. Photo by Nils Warnock, PRBO|
From the very outset, wanting to better understand the impacts of oil on wildlife, we initiated efforts to obtain the most complete and rigorous scientific data possible. Over time, our expertise in oil spill assessment has grown, and so have the positive consequences for marine bird conservation.
In January 1971, two tankers collided just outside the Golden Gate and spilled 840,000 gallons of oil. Thick black crude oil washed ashore from Drakes Beach (Point Reyes) to Point Año Nuevo (San Mateo County). This was the region's first such large-scale calamity since 1937, and California was not yet prepared to respond. Along with hundreds of other people, everyone at PRBO turned out to collect live oiled birds from beaches, take them to some of the three dozen cleaning stations, and even help try to rehabilitate them for eventual release into the wild. So little was then known about seabird rehabilitation that, despite intense efforts, most birds oiled in the 1971 spill died.
After the emergency subsided, we realized that crucial information had also been lost. Dead birds had been gathered up on beaches along with oiled kelp and other litter and disposed of without ever being counted. David Ainley, then PRBO's seabird biologist, set out to piece together an assessment of the total number of birds oiled. After accounting for 4,629 live oiled birds taken to nine cleaning stations, he estimated that at least 6,000 oiled birds had gone through all the stations. Based on reports from other spills, he speculated that a total of 20,000 birds may have succumbed. In hindsight, it was clear that a realistic number of oiled birds beaching after a spill would call for data on dead birds onshore, as well as live ones rescued.
To find out how peaks in mortality from events like oil spills might compare with natural background levels, later that year PRBO began a long-term survey of beaches throughout California. We trained and coordinated dozens of volunteer observers who walked beaches monthly, identifying dead seabirds and documenting oiling and other causes of mortality. This was the origin of the Beach Watch project, coordinated by PRBO until 1986 and administered today by the National Marine Sanctuary program.
Beached Bird Survey Meets Oil Spill
|Point Reyes Beach,1984: Rich Stallcup holds a soaked (oiled) Common Murre.
PRBO's volunteer network received an urgent call to action in November 1984. The tanker Puerto Rican had exploded offshore of San Francisco, been towed southeast, and (11 miles from the Farallon Islands) spilled an estimated 1,470,000 gallons of oil and fuel. PRBO led efforts to survey Marin and Sonoma county beaches daily, removing live and dead birds and tallying numbers.
In a stroke of foresight, we collaborated with researchers from U.C. Santa Cruz to obtain aerial surveys of the seabirds then at risk to oiling offshore. Using the beach and aerial data together, and working with a colleague whose expertise was computer modeling, we made our first comprehensive estimate of bird casualties from an oil spill—including those oiled but never recovered or counted. One example: 470 Common Murres were found on shore in the Puerto Rican spill; our model estimated that 1,770 had likely succumbed to oiling.
The next chance to develop this expertise, unfortunately, came just over a year later, in February 1986, when reports reached PRBO of oiled seabirds beaching all along Central California. The source of the oil was unknown. As the state's oil spill response network had not yet been formed, PRBO biologists took on the task of quantifying overall seabird mortality. We carried out intensive beached bird surveys from Marin to Monterey counties, focusing on counts of dead birds. Government agencies and the public soon became involved in the recovery and transport of live oiled birds to emergency cleaning centers (where mortality, sadly, was high).
Knowing the kinds of information needed for a complete assessment, PRBO again arranged for aerial surveys of seabirds at risk offshore, collated records of live oiled birds from rehabilitation centers, estimated the number of dead birds reaching shore, and collaborated on estimates of the birds that died but did not reach shore. Our estimate: approximately 9,900 seabirds died (7,500 Common Murres), though the amount of oil spilled was only some 610 barrels.
The source proved to be the barge Apex Houston, under tow from San Francisco to Long Beach with a missing hatch cover. In rough seas oil had spilled unnoticed from the open tank, fouling a long strip of wintering seabird habitat. PRBO biologists served as expert witnesses in the litigation brought by the U.S. government to recover costs of mitigating some of the damage. A settlement of nearly $6.5 million, the largest of its kind at the time, was put to good use for seabirds. Along the San Mateo County coast, U.S. Fish and Wildlife Service reestablished a colony of nesting Common Murres and acquired old-growth forest as nesting habitat for federally threatened Marbled Murrelets.
PRBO's emphasis on securing scientific data to determine an oil spill's actual toll on birds has since helped shape the cutting-edge response network in California, in which we continue to play an active role. In 1991, the State Department and Fish and Game formed an Office of Spill Prevention and Response (OSPR). In 1994, under contract with OSPR, PRBO developed the standardized protocols used in this state for data and evidence collection for oiled wildlife, and we established a team of biologists trained and available for such activities (see Diana Humple's article in this Observer).
Until and unless oil spills can be prevented, we will continue to contribute, as scientists, to the conservation of natural systems and affected wildlife.