The Information Value of Full-Retention Policies

presentationDiscard rates in marine fisheries have been estimated at more than 80% for some individual fisheries, with an average global discard rate of 8%. Discarding of catch can be problematic for three main reasons: (1) in the absence of accurate and precise discards estimates, unreliable catch data distort estimation of the appropriate quotas; (2) bycatch imposes a cost on the resource as survival rates are generally low; and (3) bycatch-induced mortality of charismatic species presents a loss of non-use values. Policy instruments to limit discarding vary from taxes on bycatch, to subsidies for selective fishing gear, to outright bans on discarding, also called full-retention policies. The 2013 reform of the European Union's Common Fisheries Policy features the introduction of such an obligation to land all catches "of species which are subject to catch limits." In this paper we aim to estimate the economic effects of a full retention policy in a mixed fishery. More specifically, we estimate the economic value of the data distortion caused by discarding of fish, and how these economic losses are ameliorated by a ban on discards. We present a bioeconomic model capable of investigating these questions in a mixed fishery for a variety of stock assessment methods, harvest control rules, and discarding policies. We apply the model to the North Sea demersal fishery, focusing on the two main commercial species plaice (pleuronectes platessa) and sole (solea solea). We find that the information value of discard bans depends largely on the prevailing harvest control rule