AbstractTraditional methods used to estimate fishing effort that maximizes rent to an open access resource have almost universally assumed all costs are directly proportional to effort. When crews receive a fixed share of gross returns, labor costs are proportional to catch; hence, rent accrues to crews as well as vessel owners under limited entry. A model that allowed costs to be proportional to effort and catch was applied to the Gulf of Mexico shrimp fishery. This study indicates that traditional analysis would result in management schemes that overtax vessels and ignore rent accruing to crews.