Understanding market competition and consumer preferences are important first steps in developing a business. In a competitive market, the effectiveness of the various elements of a firm's marketing mix depends not only on the absolute value of each element but also on the relative values of the elements with respect to the firm's position in the market. In this paper, we analyze the demand structure and market positions of a variety of seafood products in the French retail market. We used a labeled choice experiment to analyze 12 seafood species. The choice options were labeled by the names of the seafood, providing researchers the opportunity to analyze the competitive interactions among the species. Competitive clout and vulnerability measures were estimated for each species as summary measures of species competition. These measures were calculated from cross- and own-elasticities and reveal that salmon and cod have the strongest market position, while monkfish and pangasius have the weakest. In general, the demand for seafood is moderately sensitive to price (market elasticity of −1.31). Large size and low-income households, female consumers, people in the age range 35–44 years, and self-employed consumers are the most sensitive to price. Four segments were identified and described in terms of both consumer characteristics and preferences. Our results are meaningful for producers and retailers to develop marketing strategies and production plans. [EconLit citations: D12, M21, Q13].