In this paper, we present an approach to compare the impact of different
management options on the dynamics of a mixed fishery. We used ISIS-Fish, a
simulation tool aimed at evaluating the impact of spatial and seasonal
management measures on the dynamics of mixed fisheries. The French
Nephrops norvegicus (Norway lobster) – Merluccius merluccius
(hake) mixed fishery of the Bay of Biscay was chosen as a study case.
First, we parameterised the population and exploitation models. We then
selected several management measures, including marine protected areas
(MPAs) and total allowable catches (TAC), and parameterised fishermen's
reaction to each measure. Then, a sensitivity analysis was performed
according to a fractional factorial experimental design. Management
scenarios were assessed and compared using a statistical simulation design.
The sensitivity analysis showed the large influence of some parameters, such
as natural mortality, N. norvegicus fecundity, and catchability on both abundance
and catches. Given model parameters, an improvement of trawl selectivity and
several MPA designs (differing in size, seasonality and location) were found
to result in a significant increase in abundance over 10 years, especially
for N. norvegicus. This study illustrates the need for a pluri-specific approach
to fisheries assessment and management.