Dramatic Changes in Bering Sea Ecosystem Noted by NOAA

December 31, 1998

Release from:
Joyce Gross
NOAA/PMEL - Seattle, Washington
Many rarely observed conditions occurred in the Bering Sea during the summers of 1997 and 1998, including extensive die-offs of seabirds, rare algal blooms, unanticipated low salmon runs, warmer than usual ocean temperatures, and altered ocean currents and atmospheric conditions. These changes prompted scientists from NOAA, the federal agency that protects and predicts the nation's marine resources and atmospheric environment, to convene an international workshop in Seattle, Wash.
"People whose livelihood depends on the Bering Sea need to know if these are fleeting anomalies or persistent large-scale changes," said James Balsiger, head of the National Oceanic and Atmospheric Administration's Alaska Fisheries Science Center. "Scientists want to determine the cause of these unusual conditions and their portent for the future of this national resource."
The eastern Bering Sea provides almost half of the fish and shellfish caught in the United States. Most of the catch comes from the continental shelf, a broad, shallow area larger than the state of California, that borders Alaska's western coast. Besides producing abundant fish and shellfish, the shelf also supports large numbers of resident and migratory birds and marine mammals.
A prominent theme of the workshop was the implication of recent environmental changes on the management of living marine resources. Reports from those attending the workshop will now be available via the Internet for a broader review and comment by U.S. and world environmental scientists.
"We wanted to bring together scientists, environmentalists, administrators, resource managers, native Alaskans, representatives of the fishing industry, and others at this crucial time," said Eddie Bernard, director of NOAA's Pacific Marine Environmental Laboratory in Seattle. "During the workshop, more than 75 participants shared information, proposed reasons for these environmental changes, and suggested future research needs. They also discussed ways to use Internet technology to report news and facilitate communication."
Workshop participants reported information related to the environmental occurrences. Atmospheric processes in 1997, partially in response to El Nino, caused clearer skies, calmer seas, and warmer sea temperatures than normal in the eastern Bering Sea. "The warmest water temperatures ever recorded on the eastern Bering Sea shelf occurred during the summer of 1997," said Phyllis Stabeno, an oceanographer at the Seattle lab.
The most striking event was the appearance of extensive areas of milky, aquamarine water over most of the shelf in 1997. The water's unusual color was caused by a massive bloom of coccolithophores (a type of nontoxic, microscopic marine plant). These blooms have never before been observed in the Bering Sea for extended periods. The coccolithophores replaced the normal summer plankton community. This replacement made profound, but not well understood, effects on the rest of the food chain. Despite different atmospheric conditions in 1998, the bloom recurred.
Other recent changes in the ecosystem included unprecedented mortality of short-tailed shearwaters and unsuccessful reproduction rates for kittiwakes (both common seabirds frequenting the area during summer). Salmon runs were far below expected levels. The fish were smaller than average, and traditional migratory patterns seemed altered. There was an unusual sighting of Pacific white-sided dolphins in Bristol Bay, and large numbers of baleen whales appeared on the shelf. Taken together, these events show how responsive the ecosystem is to climate and suggest that climate change would have a strong effect on the ecosystem.
Although these unusual conditions did not seem to have an immediate effect on the groundfish of the area, they may impact future abundance. NOAA Fisheries surveys in 1997 and 1998 located fewer young-of-the-year pollock than in previous years. However, other studies conducted in 1998 suggest that young pollock, in fact, were quite abundant but located further onto the shelf than usual. This displacement could derive from transport of pollock larvae northeastward from their spawning area due to windy conditions during spring. Ramifications of these recent changes won't be known for several years until the young pollock mature into adult fish and are harvested.
An important task is to determine linkages between the unusual conditions and the Bering Sea's bountiful resources of salmon and pollock. Workshop participants agreed that focused, long-term, integrated research is needed, and recommended the recently written Draft Science Plan for the Bering Sea Ecosystem. Incorporating traditional knowledge from native communities into the information available to research programs is also vital, scientists acknowledged. Participants discussed the challenge of preserving the diverse populations of fish, marine mammals, and birds in this highly variable environment.
NOAA scientists are seeking review and input from scientists throughout the globe. A summary of the workshop will be available December 31 on the Bering Sea and North Pacific Ocean web site http://www.pmel.noaa.gov/bering/.