摘要:Mortality is one of the most important demographic features. Measures of size- or sex-specific mortalitycan help to explain local selective pressures and can also be used to construct demographic models that estimatepopulation trends. This study estimated mortality rates for 2 populations of a viviparous freshwater fish, endemic towestern Mexico (Poeciliopsis baenschi). We found that mortality was size- and sex-dependent and different betweenboth populations. We compared our findings with mortality rates previously estimated for other populations of thisspecies.