Herring Declines at Cherry Point: Finding the Real Cause

One way the Marine Ecosystem Health Program (MEHP [now the SeaDoc Society]) works to ensure the health of marine wildlife populations and their Pacific Northwest inland waters ecosystem is to fund scientific research. Research projects are carefully selected to ensure that each one provides information needed to better manage marine resources throughout the inland waters region. For this edition of the quarterly MEHP Research Update, we would like to highlight some early results from one of the projects the MEHP funded in 2002. This research project, entitled “What are the causes of developmental abnormalities in Cherry Point herring?” investigated some important aspects of herring declines in Puget Sound.

Pacific herring (Clupea harengus pallasi) are a critical part of the food chain within the inland waters of Washington and British Columbia. These small fish feed primarily on planktonic crustaceans. Larger fishes, marine birds, and marine mammals, in turn, feed on herring. Within the inland waters of Washington State, there are 18 stocks of herring, each group defined by its distinct spawning ground.

The Cherry Point herring stock is one of Washington’s most important. It was once Puget Sound’s largest herring stock and, unlike most of Washington’s herring, which are winter-spawning, the Cherry Point Stock is spring-spawning. Unfortunately Cherry Point herring have declined 94% between 1973 and 2000 (see graph below). They are using less and less of their historic spawning grounds, larvae hatch with reduced survival potential (reduced fitness), and the adult survival rate has declined. Decline of Cherry Point Herring (1973-2000) (Graph Courtesy of Washington Department of Fish and Wildlife) Historically, Cherry Point herring spawned from the north end of Bellingham Bay north to the Canadian border. As it so happens, Cherry Point, in the center of the spawning grounds, is home to some of the largest industrial plants in Washington. Some scientists and fisheries biologists have wondered whether the reduced fitness of Cherry Point herring larvae was possibly due to their exposure to chemicals during maturation.

In 2002, the MEHP awarded funding to Drs. Hershberger, Naish, and Kocan from the U.W. School of Aquatic Fishery Sciences and the USGS Marrowstone Marine Station to answer this important question. Using a series of well designed experiments, these scientists found that Cherry Point herring larvae had similar weights and a similar incidence of developmental abnormalities regardless of whether they developed in the waters at Cherry Point or were incubated in clean laboratory water or were transplanted and developed in other areas of the Puget Sound which are considered uncontaminated. Finding that the developmental abnormalities detected among larvae at Cherry Point are NOT the result of exposure to site-related conditions (toxins or other products) during development is important. Causes for declines in the abundance of marine resources like the Cherry Point herring stock are not usually easy to understand. When Washington’s once-largest herring stock declines 94% and it just happens to spawn near the home of some of the state’s largest industrial plants, most people assume the two facts are connected. Hershberger, Naish and Kocan’s work suggests that the toxins or other products that may be present in the water at Cherry Point are not the cause of larval developmental abnormalities or reduced weights in newly hatched larvae in Cherry Point herring. They are not yet finished with their MEHP-funded project, and more work still needs to be done to understand all of the factors responsible for the decline in Cherry Point herring, but these early results are a good example of how our efforts to understand and reverse species declines needs to be based on good science and not just appearances.

Thank you again for taking an interest in the work of the Marine Ecosystem Health Program. For more information about the research highlighted in this update or other important research projects funded by the MEHP, please visit the SeaDoc website.

Sincerely,

Kirsten V.K. Gilardi, DVM, Dipl. ACZM Program Coordinator

Joseph K. Gaydos, VMD, PhD Staff Scientist and Veterinarian