Abstract: The sustainable utilization of fishery resources urgently requires effective assessment methods. Traditional assessment approaches are constrained by their substantial data requirements, which has accelerated the development of data-limited evaluation methods. Among these, the Monte Carlo Catch-MSY (CMSY) model, which requires only catch data, has been widely applied. However, its parameter settings may significantly impact the results. Therefore, we selected 15 major economic fishpopulations in the Western Indian Ocean to analyze the parameter sensitivity of the CMSY model and assess their stock status. The results show that there were differences in the response of different fish populations to changes in model parameters (B_end/k), with hilsa shad (Tenualosa ilisha) and swordfish (Xiphias gladius) being the most significant. Except for bombay-duck (Harpadon nehereus), false trevally (Lactarius lactarius) and bigeye tuna (Thunnus obesus). All other fish stocks are considered to be both subject to overfishing and overfished. Compared with previous studies, the results of the CMSY model for pelagic fishes and other groundfishes are generally consistent, while for tuna, there are significant differences with the assessment results by Indian Ocean Tuna Commission (IOTC) by using data-rich methods. Therefore, the CMSY model performs poorly in the assessment of tuna but has good applicability and reliability in the application of small pelagic fishes and other groundfishes.