LONG-TERM TARGETS FOR THE CELTIC SEA MIXED-SPECIES MULTI-METIERS FISHERIES

A deterministic, forecasting, equilibrium study has been conducted of the multispecies and multi-metier fisheries of the Celtic Sea, ICES di visions VIIf and g. Calculations have been made of the optimal fleet s izes and mesh sizes required to maximize objectives of joint relative sustainable yields, gross revenue and net revenue. The species modelle d are the resident populations of cod (Gadus morhua), whiting (Merlang ius merlangus), sole (Solea solea), plaice (Pleuronectes platessa) and Norway lobster (Nephrops norvegicus), with additional consideration g iven to catches of hake (Merluccius merluccius), monkfish (Lophius sp. ) and megrim (Lepidorhombus whiffiagonis). The fleet metiers modelled are the beam trawls, Nephrops otter trawls and non-Nephrops otter traw ls. If mesh sizes can be calculated independently for each metier, the n the yields and the gross revenue are maximized by increased effort a nd mesh sizes, especially in the non-Nephrops fleet. If a common mesh size is required for all fleets, then the yields and the gross revenue are maximized when (i) this mesh size is of 114 mm, (ii) the fishing effort in beam and Nephrops fleets is significantly increased, (iii) t he non-Nephrops fleet is almost eliminated. Maximization of net revenu e requires a mesh size similar to the current mesh of 80 mm, but with significant reductions of fishing effort in all fleets. Average profit ability is increased by 50 millions EUROs per year for the Celtic Sea fishery. The model provides a basic structure for examining the manage ment with a more realistic dynamic and stochastic description of the C eltic Sea fisheries.