Changes in fish assemblage structure after implementation of Marine Protected Areas in the south western coast of Portugal

Abstract

Marine Protected Areas (MPAs) are increasingly being recommended as management tools for biodiversityconservation and fisheries. With the purpose of protecting the region's biodiversity and preventthe over exploitation of marine resources, in February 2011 the no-take MPAs of Ilha do Pessegueiro andCabo Sard~ao were implemented within the “Parque Natural do Sudoeste Alentejano e Costa Vicentina“(PNSACV) Marine Park, south western coast of Portugal. As such, commercial and recreational fishingbecame prohibited in these areas. In order to evaluate the effects of these no-take MPAs, the structure oftheir fish assemblages and of adjacent control areas without fishing restrictions were studied between2011 (immediately after implementation) and 2013 (two years after implementation). A total of 4sampling campaigns were conducted (summer 2011, winter 2012, summer 2013 and winter 2013) usingtrammel nets and bottom trawl. Ichthyofaunal assemblages from the no-take MPAs (treatment) werecompared with adjacent areas (controls) and changes evaluated as a function of time since protection.Results revealed significant increase in fish abundance after the implementation of the no-take MPAs.Furthermore, significant differences in the structure of fish assemblages (abundance and fish size) betweenprotected and neighbouring areas were rapidly observed upon the implementation of the no-takeMPAs. In addition, specimens of larger size occurred more frequently within Ilha do Pessegueiro no-takeMPA in the last year of the study. Overall, despite the young age of these no-take MPAs, changes on thestructure of their fish assemblages were already evident after only two years of protection, indicatingthat management measures such as MPA designation may play an important role to promote fisheriessustainable exploitation as well as to protect species with conservation interest.