This document discusses using financial calculations to inform fisheries management decisions in Thai trawl fisheries. It presents data on costs, earnings, and internal rates of return for 14-18m otter trawlers. Sensitivity analysis shows the IRR is most sensitive to changes in fuel price, trash fish price, and number of fishing days. Two scenarios are analyzed that increase prices and reduce fishing days, resulting in a higher IRR of 11.85%. Management questions are raised about reducing fishing effort by having fewer fishing days per vessel and paying processors to increase prices, which could reduce bycatch by nearly 3,000 tonnes annually across 1,500 boats.