Reproductive Cycles in Sturgeons with a Special Focus on the Farmed Siberian Sturgeon

Abstract

The chapter reports the published data on biological cycles and/or puberty in sturgeons for both wild and farmed brood stocks. There are three main lines to document these data, the analysis of large-scale sampling or landings, the analysis of sampling with previously tagged fish and the echography which has a remarkable efficacy. Both biological characteristics are lower for farmed fish as compared with their wild counterparts. This is mainly due to water temperature and food availability which favour the growth in farmed conditions. There are observations which suggest that the more precocious and the more frequent the spawning, the smaller the fish. A yearly spermiation is the most common figure in farmed males, while 2-year period is the most frequent for the females. Thanks to a 5-year survey on a given cohort of farmed Siberian sturgeon, the figure of the biological cycles is as follows: there are two types of cycles, the single and the recurring. In the first batch, the 2-year cycle is the most frequent (32%), while the 3-year cycle accounts for nearly 11%. In the second batch, a 2-year cycle represents 20%, and the 1 + 2 or the 2 + 1 recurring cycles account for nearly 32%. Altogether the 2-year cycles may represent up to 84%. This explains that the relative number of yearly spawnable females exhibits a 2-year variation from a minimum of 35–45% up to a maximum of 59–63%. There are data showing that the yearly number of mature females depends on time lapse of domestication duration with variable percentages depending on generation and period.