The Korean fishing industry is currently subject to overexploited resources arising from excessive levels of fishing effort. Measures to reduce effort in the industry have been instigated. However, for the mixed gear, multi-species inshore fleet, determining the appropriate level of effort is problematic. This is made more difficult through limited catch and effort data. In this paper, a simple surplus production bioeconomic model for the flounder fishery is developed based on different effort standardisation approaches to estimate the optimal level of effort in the fishery. The model is based on a subset of catch and effort data, and implications of this for the assessment of global effort levels are considered. The results indicate that even with poor information, relatively robust estimates of necessary reductions in fishing effort can be derived.