Thursday, November 2
Changes in Pacific Coast Abalone in Response to Long-term Climate Change
Over the last several decades profound changes have occurred in marine ecosystems along the Pacific Coast. These changes have occurred in response to variety of factors but climate change has been a major driver of many changes. Changes in climate have included a gradual warming of the ocean surface superimposed over the Pacific Decadal Oscillation and punctuated by a series of El Nino events of varying intensity. Changes in the marine ecosystem in response to these physical changes have included a major reduction in marine productivity which has resulted in strong declines in plankton, fishes, and seabirds as well as numerous other species.
One striking change has been severe declines in black abalone populations along the California coast, which once carpeted the shores of the California Channel Islands. Beginning in the mid-1980's black abalone began to decline precipitously in response to the appearance of a new pathogenetic bacteria which causes “withering syndrome” in association with above average sea temperatures. Black abalone were virtually eliminated in southern California in the 1980's and the disease spread north to central California in the 1990s in response to El Nino events in 1991-95 and 1997-98. Currently, the black abalone fishery is closed, populations are reduced by over 95% in areas south of San Luis Obispo County, and the density of these adult stocks are likely reduced below levels where they can sustain viable populations. Black abalone are currently being examined for potential listing under the Endangered Species Act.
Brian Tissot is an Associate Professor of Environmental Science at WSU Vancouver. His research is focused on the importance of habitat in fishery biology, management and policy. His current projects involve monitoring and recovery of black abalone populations in California; habitat assessment of groundfish populations on west coast continental shelves; and the evaluation of the effectiveness of marine protected areas to enhance aquarium fisheries in Hawaii.