Two Artemia populations, a bisexual from San Francisco Bay (California, USA) and a parthenogenetic from Tanggu area (Tianjin province, People's Republic of China) are assayed for their tolerance and fitness in various salinity levels . This study was carried out under laboratory conditions where salinity effects upon special characteristics of the two Artemia populations, such as survival, growth rate, maturation, morphology, fecundity and life duration, were recorded . This evaluation revealed that the two populations examined exhibit significant differences in their response against elevated salinity levels . Furthermore, specific biometric parameters can be a useful tool for the discrimination and/or determination of their distribution in a mixed population, which, in fact, is the case in Tanggu salt works. Artemia franciscana seems to be a more effective colonizer at higher salinities . The data presented in this study may generate useful suggestions for proper management of the solar saltworks at Tanggu although further experimentation is needed .