| |
 |
|
|
Photo by Denise Greig
Photo by Tom Grey
The Estuary's fish populations are in decline. Populations of four important species of estuarine fish—the endemic and threatened Delta smelt, the introduced striped bass, the native longfin smelt, and the introduced threadfin shad—have been declining since 1967, with a precipitous drop in 2002. The Estuary's salmon populations have also declined, and commercial fishing for salmon on the California coast was banned in 2008 and 2009. Steelhead trout—once common in our rivers and streams—are a federally-listed endangered species, and there are fears that hatchery-raised fish may be harming wild populations.
Many species of wildlife around the Estuary have declined or disappeared. Ninety taxa of insects, amphibians, reptiles, birds, and mammals within the Estuary have been designated by federal and state governments as deserving special protection or monitoring. Of these 90 taxa, 68 percent have been depleted by the loss of wetlands and riparian areas. At least seven insect species, one reptile species, three bird species, and five mammal species have disappeared from the Estuary, primarily due to habitat loss, and the California tiger salamander, California red-legged frog, giant garter snake, Western pond turtle, and several butterfly species are in danger of disappearing as well.
Many of the Estuary's wildlife species are contaminated with pollutants; elevated levels of mercury have been found in the endangered California clapper rail. Some of the highest concentrations of PBDEs (used in flame retardants in recent years) in the world have been found in the Estuary's harbor seals, mussels, Forster's terns, and fish. Although these contaminants may not kill an animal outright, scientists are concerned about "sub-lethal" effects, such as immune system disorders and reproductive failure. For more information about PBDEs and wildlife, see http://www.sfei.org/rmp/rmp_news/RMP2008News_Vol13SpringSummer4Web.pdf. |
| |
| |
