Delta smelt
From Wikipedia, the free encyclopedia
| Delta smelt | |
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| Delta smelt, Hypomesus transpacificus | |
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Osmeriformes |
| Family: | Osmeridae |
| Genus: | Hypomesus |
| Species: | H. transpacificus |
| Binomial name | |
| Hypomesus transpacificus |
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Delta smelt, Hypomesus transpacificus, are slender-bodied smelts, about 5 to 7 cm (2.0 to 2.8 in) long, of the Osmeridae family. They have a steely blue sheen on the sides and seem almost translucent. Smelts live together in schools and feed on zooplankton (small fishes and invertebrates). One female may lay from 1,400 to 1,800 eggs. Mature unfertilized eggs are about 1 mm (0.039 in).
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[edit] Habitat
Delta smelt are currently endemic to the Sacramento Delta, California, where it is distributed from the Suisun Bay upstream through the Delta in Contra Costa, Sacramento, San Joaquin, Solano and Yolo counties. The delta smelt is a pelagic (live in the open water column away from the bottom) and euryhaline species (tolerant of a wide salinity range). They have been collected from estuarine waters up to 14 ppt (parts per thousand) salinity.
[edit] Life cycle
Most delta smelt live one year and die after their first spawning (semelparous). Delta smelt spawning occurs in spring in river channels and tidally influenced backwater sloughs upstream of the mixing zone (saltwater-freshwater interface). The Sacramento and San Joaquin rivers then transport the delta smelt larvae downstream to the mixing zone, normally located in the Suisun Bay. Young delta smelt then feed and grow in the mixing zone before starting their upstream spawning migration in late fall or early winter.
Delta smelt are preyed upon by larger fish, especially striped bass and largemouth bass which are invasive species in the Sacramento Delta.[1]
Delta smelt used to be a common fish in the Sacramento - San Joaquin rivers estuary. The population is much smaller than historically and the species was listed in 1993 as threatened under the California Endangered Species Act (CESA) and Federal Endangered Species Act (FESA) (Federal Register 58:12863; March 5, 1993). Critical habitat was listed for delta smelt on December 19, 1994 (Federal Register 59:65256). In 2008, the California Fish and Game Commission moved to uplist delta smelt to endangered under CESA.
[edit] Court protection
On August 31, 2007, California Federal Judge Oliver Wanger of Federal District Court protected the rare declining fish delta smelt by severely curtailing human use water deliveries at San Joaquin-Sacramento River delta from December to June.[2] These are the pumps at the Banks Pumping Plant that send water to Central and Southern California for agricultural and residential use.
Now there is controversy that this protection has hurt California farming, now that they are facing a drought, since pumps were turned down over the fish. Many attribute this decision to the devastation of hundreds of thousands of acres of farm land and the loss of tens of thousands of jobs in the central valley.[3]
[edit] See also
- Banks Pumping Plant
- Sacramento-San Joaquin River Delta
- California Aqueduct
- Metropolitan Water District of Southern California
- Snail darter
- Rio Grande Silvery Minnow
[edit] References
- Gimenez Dixon (1996). Hypomesus transpacificus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006. Listed as Endangered (EN B1+2 cd v2.3)
[edit] External links
[edit] Notes
- ^ Raymond Bark, Brent Bridges, Dr. Mark D. Bowen, (2008). "2008 Tracy Research Study: Plan Predator Impacts on Salvage Rates of Juvenile Chinook salmon and Delta Smelt". http://www.usbr.gov/pmts/tech_services/tracy_research/studyplan/StudyPlan2008-012.html. Retrieved 2009-06-26.
- ^ New York Times, California Judge Helps Declining Fish
- ^ Water Shortage In The Central Valley
