Titlebook: Sturgeon biodiversity and conservation; Vadim J. Birstein,John R. Waldman,William E. Bemis Book 1997 Springer Science+Business Media Dordr

吝啬性

cumulative

Sturgeon rivers: An introduction to acipenseriform biogeography and life history and the range of life history patterns displayed by different species. Our biogeographic analysis (based on the most recent phylogenetic analysis including fossil Acipenseriformes) suggests that Acipenseriformes originated in Europe, and that early diversification took place in Asia. Acipenseriform

Ergots

Euphonious

Endangered migratory sturgeons of the lower Danube River and its deltageon . and perhaps European Atlantic sturgeon .. The freshwater sterlet . thrived in the Danube and its tributaries. Presently, only three anadromous species occur in the Romanian part of the Danube, . and ., while . lives in the Danube and its tributaries. Extreme depletion in the number of sturgeo

LAP

offense

Species structure, contemporary distribution and status of the Siberian sturgeon, rms can be described as threatened or endangered. Recently, the abundance of the nominal subspecies, ., which inhabits mainly the Ob River basin, decreased sharply. Due to construction of hydroelectric dams, up to 40% of the spawning grounds became inaccessible for migrating sturgeon of this subspec

隼鹰

挥舞

Observations on the reproductive cycle of cultured white sturgeon, and puberty are highly asynchronous in the female stock. Gonadal cycles are annual in males and biennial in females, and gametogenesis is influenced by season. Neuroendocrine regulation of reproduction appears to involve a dual gonadotropin system controlling gonadal development and spawning. Labil

Small-Intestine

chalice

Life history and status of the shovelnose sturgeon, ican sturgeons, seldom weighing more than 2.5 kg over most of its range except in the upper Missouri River, where individuals of over 7 kg have been found. Spawning occurs in spring at temperatures between 17 and 21 °C over rock or gravel substrate down-stream from dams, near rock structures, or in