The fishery for Norway lobster off the portuguese coast: a biological and economic assessment

Leocádio, Ana Maria Colaço

http://hdl.handle.net/10400.1/747

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Authors

Leocádio, Ana Maria Colaço

Advisor(s)

Castro, Margarida

Whitmarsh, David

Abstract(s)

Norway lobster (Nephrops norvegicus) is mainly caught off the South and Southwest coasts of Portugal, using two different types of gear, bottom trawling and creels. Trawling is the traditional fishing method, where Nephrops can be either a target species or by-catch of shrimp trawling. Creels are only used in areas unavailable to trawlers, either due to legislative restrictions on access or to unsuitable seabed. Creels have Nephrops as the only target species, but the fleet uses other gears to target other species. During the lasts decades, the modernisation of the trawling fleet with the resulting technological improvements, has lead to an increase in fishing effort. Nowadays, the two populations on the South and SW coast are considered outside biological safe limits, and a recovery plan is underway. Two typical vessels, in each fleet (trawling and creels), were selected to collect biological and economic data. Results show that the size composition of the catches is very different for the two gears used. Trawl catches are composed of small individuals usually in bad condition, while creel catches are composed of large and alive individuals (very high commercial value). It is assumed that the size composition obtained with creels results from the selectivity of the creel and the fact that these populations are exploited at much lower fishing levels. An assessment was made of the lobster fishery in order to evaluate its economic potencial. Results suggest that creels should be the only gear used, as it represents a very selective gear that could help the recovery of Nephrops stocks and allows a good economic return for the vessels involved. Thus, transference of fishing effort from trawling to creels is recommended.