Urmia Lake is a large hypersaline lake situated at north-west of Iran, 21 km from Urmia city. The salinity of Urmia Lake has increased tremendously since 1998 and reached to about 350 ppt in 2008-2009. It was reported by Agh and Noori (1987) that Artemia urmiana hatches best at 30-35 ppt salinity. Therefore it seems that one of the main reasons for reduced population size in Urmia Lake could be inability of Artemia cysts available in Urmia Lake to hatch due to very high salinity. There are reports by other scientists that cysts of different species and populations of Artemia prefer varying range of salinities for hatch (Versichele and Sorgeloos, 1980, Tackaert et al., 1987, Dana and Lenz, 1986). The aim of this research was to understand the hatching capacity of Artemia urmiana and parthenogenetic Artemia at different salinities ranging from 33 to 330 ppt.
