Conservation impacts on protected sea turtles and marine mammals are a longstanding concern in U.S. swordfish fisheries, including the Hawaii shallow-set longline (SSLL) fishery and the west coast drift-gillnet (DGN) fishery. Observer records for these fisheries document a history of rare-event interactions with large cetaceans and endangered sea turtles. Since 2001, leatherback and loggerhead sea turtle interactions in the SSLL fishery have been limited by hard caps, or common-pool limits on the numbers of observed interactions which may occur before the fishery shuts down for the remainder of a season. More recently, in September 2016, the Pacific Fishery Management Council adopted hard caps to strictly limit annual DGN fishery interactions with a range of protected species including fin whale, humpback whale, sperm whale, leatherback turtle, loggerhead turtle, olive ridley turtle, green turtle, short-fin pilot whale, and bottlenose dolphin. Hard caps create a tradeoff between protected species conservation and potential fishery production. Caps set low enough to make closure early in the season a likely event may result in lost fishing effort and quasirents. Uncertainty over closure timing increases the risk to fishing livelihoods. A bootstrap analysis has been developed to simulate the conservation and economic effects of hard caps on DGN fishery operation. Observer, logbook and landings databases and cost-and-earnings survey data are used to calibrate the analysis. Results suggest a substantial loss of economic viability with limited conservation benefits may occur if caps are set at levels which are likely to trigger early season closure.