We present a simulation bioeconomic model based on an age-structured
population biological sub-model and an economic sub-model with
vessel-specific dynamics, applied to two red shrimp (Aristeus antennatus) stocks in the NW
Mediterranean. The model is dynamic, the economic sub-model is disaggregated
at the level of vessel and the two sub-models are linked by means of a
fishing mortality vector. We analyzed the projection of selected indicators
(catches, overall profits, fishing mortality and spawning stock biomass) for
the target species of the deep-water trawl fishery in the NW Mediterranean,
red shrimp. We built three alternative management scenarios based on input
control and we examined the performance of these management strategies
against the current management policies. The three alternative management
strategies were: i) increase the cost of effort by eliminating the fuel tax
exemption currently in place, ii) limit the nominal effort level (days at sea)
to current levels, in order to offset the increasing trend observed in the
last decade, and iii) change the selectivity patterns of the trawl by increasing
mesh size. Our results show that for the two stocks analyzed, any of the
three management measures (input controls) would be beneficial both to the
stock and the fleets (over the medium and long terms) when compared with the
projections over time of the statusquo. Improving the selectivity of the fishing
gear is more beneficial than limiting nominal effort or increasing the cost
of effort. Comparing the performance of the management strategies on two
stocks, one heavily fished and the other moderately so, we show that none of
these management measures is able to substantially redress the situation of
a heavily fished stock, implying that for the full recovery of heavily
fished red shrimp stocks, we need to contemplate even stricter measures of
management.