Disaggregating species unit costs in mixed fisheries: the case of the Irish whitefish fleet

Many fishing fleets operate in mixed fisheries where several target species are caught together along with other bycatch species unintentionally caught. In some cases, fleets operate in multiple mixed fisheries depending on various factors such as time of year or current market conditions, among other factors. Data collection in the European Union (EU) involves various levels of detailed data. Economic data is generally collected on an annual time-step whereas other sources provide information at much higher resolution such as the fishing trip (landings declarations), fish day (logbook) or even in real-time (electronic logbook). In this paper a methodology is described to disaggregate the annual cost of a fleet segment into a cost per fishery and per species within the fishery. This information is of interest as it permits incorporation of the economic implications of fishery dynamics into fisheries management. Assessment of these unit costs on a fishery basis also allows accurate input into value chain analysis which is carried out on a species basis.