Profile Information

Gender: Do not display
Member since: Tue Aug 28, 2012, 07:58 PM
Number of posts: 26,941

About littlemissmartypants

And can it be that in a world so full and busy, the loss of one creature makes a void so wide and deep that nothing but the width and depth of eternity can fill it up!" ~Charles Dickens ****************************************************** The Delta Smelt, Hypomesus transpacificus ****************************************************** (Hypomesus transpacificus) is an endangered[1] slender-bodied smelt, about 5 to 7 cm (2.0 to 2.8 in) long, in the family Osmeridae. Endemic to the upper Sacramento-San Joaquin Estuary of California, it mainly inhabits the freshwater-saltwater mixing zone of the estuary, except during its spawning season, when it migrates upstream to fresh water following winter "first flush" flow events (around March to May).[4] It functions as an indicator species for the overall health of the Delta's ecosystem.[5] Delta Smelt are usually found at temperatures of less than 25 °C and prefer temperatures of around 20 °C. They are euryhaline but occur mostly at salinities of 0–7 practical salinity units.[6] ************************************************* Because of its one-year lifecycle and relatively low fecundity, it is very susceptible to changes in the environmental conditions of its native habitat.[7] It is listed as a federally threatened species under the Endangered Species Act of 1973.[2][3][8] Efforts to protect the fish from further decline and extinction have focused on limiting or modifying the large-scale pumping activities of state and federal water projects at the southern end of the estuary, thereby limiting water available to farming. However, these efforts have not prevented the species from becoming functionally extinct in the wild.[9] ************************************************* Delta smelt is easily confused with longfin smelt (Spirinchus thaleichthys). They are both small, pelagic fish species native to the estuarine and coastal waters of the Pacific coast, but they exhibit distinct ecological, morphological, and behavioral characteristics. The delta smelt, a key indicator species, is endemic to the San Francisco Bay-Delta and has a slender body averaging 5–7 cm in length, with a translucent appearance and a faint, blue lateral line. It primarily inhabits low-salinity waters and is critically endangered due to habitat loss and water management practices. In contrast, the longfin smelt is slightly larger, typically reaching up to 15 cm, and is distinguished by its long pectoral fins that extend beyond the base of the pelvic fins. **************************************************** Snip...more... Genetic studies of delta smelt populations in recent years have revealed potential signs of adaptation to environmental changes, such as increased tolerance to warmer water temperatures. These changes are thought to be driven by the increasingly challenging conditions in the San Francisco Estuary, where rapid alterations in water temperature, salinity, and habitat availability have exerted selective pressures on the species. Evidence of genetic differentiation between wild and hatchery populations has also been observed, raising concerns about the long-term viability of hatchery supplementation programs designed to conserve the species.[14] *************************************************** https://en.m.wikipedia.org/wiki/Delta_smelt