The Future of Fish in Response to Large-Scale Change in the San Francisco Estuary, California

摘要

The San Francisco Estuary is the largest estuary on the west coast of North America and one of the most altered. It supports a diverse fish fauna in which key species are in severe decline. The estuary is faced with catastrophic structural and ecological changes, especially in the Sacramento-San Joaquin Delta and Suisun Marsh, as the result of levee failure caused by the combination of earthquakes, land subsidence, sea level rise, and increased high outflows events (from climate change). The resulting flooding of Sacramento-San Joaquin Delta islands and Suisun Marsh is predicted to disrupt California's water supply system and, consequently, the state's economy. From a fish perspective, the changes seem likely to create conditions in which key nativespecies and striped bass can persist at least at present low levels, after a period of possible high mortality created by the initial flooding events. Taking actions to regulate ecological changes in the estuary before a disaster occurs could actually improve conditions for desirable fishes while being highly compatible with delivering services the Sacramento-San Joaquin Delta provides, especially water supply. Specific actions include improving habitat for fish in Suisun Marsh, Cache Slough, the YoloBypass, and the San Joaquin River, while creating islands in which flooding can be managed. The key is increasing and maintaining habitat heterogeneity. The present situation in the estuary represents an unprecedented opportunity to reverse the impacts of more than 150 years of undesirable ecological change.