An Irish commercial fishery for orange roughy began in the Northeast Atlantic in 2001 with the assistance of government grants. The fishery began as an open access, non-quota fishery. The rapid boom and bust of many deep water fisheries was experienced. Landings peaked in 2002 and then dropped significantly the following year. Many vessels were forced out of the fishery due to high costs and rapidly declining stocks. By 2005 the fishery was largely closed. Applying a bioeconomic analysis, this paper shows why the fishery no longer exists and discusses both the external and opportunity costs of the fishery. A bioeconomic model is applied to the available data to assess the open access effort and harvest with and without government grant aid. The results suggest that in the absence of subsidies, deep water trawling would not have been viable. In addition to the financial costs such as high fuel consumption, there are also externalities associated with deep water trawling. Orange roughy is closely associated with deep water ecosystems such as seamounts and cold water corals. This paper examines the costs of damage to cold water corals. These costs include the loss of fish habitats and lost future use and preservation values.