Publication Abstract

Long-term targets for the Celtic Seamixed-species multi-metier fisheries

P. Marchal and J.W. Horwood

A deterministic,forecasting, equilibrium study has been conducted of the multispecies and multi-metierfisheries of the Celtic Sea, ICES divisions VIIf and g. Calculations have been made of theoptimal fleet sizes and mesh sizes required to maximize objectives of joint relativesustainable yields, gross revenue and net revenue. The species modelled are the residentpopulations of cod (Gadus morhua), whiting (Merlangius merlangus), sole (Soleasolea), plaice (Pleuronectes platessa) and Norway lobster (Nephropsnorvegicus), with additional consideration given to catches of hake (Merlucciusmerluccius), monkfish (Lophius sp.) and megrim (Lepidorhombus whiffiagonis).The fleet metiers modelled are the beam trawls, Nephrops otter trawls and non-Nephropsotter trawls. If mesh sizes can be calculated independently for each metier, then theyields and the gross revenue are maximized by increased effort and mesh sizes, especiallyin the non-Nephrops fleet. If a common mesh size is required for all fleets, then theyields and the gross revenue are maximized when (i) this mesh size is of 114 mm, (ii) thefishing effort in beam and Nephrops fleets is significantly increased, (iii) thenon-Nephrops fleet is almost eliminated. Maximization of net revenue requires a mesh sizesimilar to the current mesh of 80 mm, but with significant reductions of fishing effort inall fleets. Average profitability is increased by 50 millions EUROs per year for theCeltic Sea fishery. The model provides a basic structure for examining the management witha more realistic dynamic and stochastic description of the Celtic Sea fisheries.

Reference:

P. Marchal and J.W. Horwood, 1998. Long-term targets for the Celtic Sea mixed-speciesmulti-metier fisheries. Aquatic Living Resources, 9: 81-94.