The closure of the Hawaiian longline swordfish fishery over the period 2001-2004, which was motivated by the protection of endangered sea turtles, created the elements of a natural experiment that allows identification of the market transfer of catch (and sea turtle by-catch) to other regions. This paper exploits the fact that the vessels in the Hawaiian longline fishery sell their catch in the US fresh swordfish market to analyze the pattern of changes in US fresh and frozen swordfish consumption both before and after the closure regulation was imposed. The mechanisms by which any unintended consequences on endangered sea turtles in other fishery locations in the world are shown to take place through the US swordfish market. At the estimated annual market transfer, a bootstrap analysis of the probability distribution of by-catch rates indicates that the regulation led to an additional 2,882 sea turtle interactions at the sample means.