Effects of marine protected areas on coastal fishes across the Azores archipelago, mid-North Atlantic

Marine reserves across different eco-regions and habitats have proven to benefit exploited fish populations within their borders. There is also mounting evidence, mostly from continental shelf regions, that such positive effects will depend on the species ecological traits (e.g. mobility) and on the characteristics of the reserves (e.g. design, age and enforcement). This study examines the effects of protection on commercial coastal fishes with different ecological traits from three marine reserves with distinct habitats (coastal vs. offshore reefs), protection regime (legal vs. voluntary, partial vs. total protection) and age (8, 15 and 26 years old) across the oceanic archipelago of the Azores, mid North Atlantic. Overall, positive effects of protection on fish abundance or individual size were limited to species of larger maximum size and lower mobility in reserves with higher compliance levels. This result agrees with many studies elsewhere showing that reserves of small size and/or insufficient compliance do not provide adequate protection to the entire fish community, limiting their contribution to manage fisheries and conserve biodiversity. That might very well be the case of Azorean marine reserves but a more conclusive result will require testing the effects of protection on larger, well enforced reserves, which still do not exist in the region. There was also a clear influence of depth in commercial fish distribution and a common preference for substrates of higher complexity across ecological traits. Combined, these results highlight the need to include complex reef structures, diverse coastal habitats and larger areas when designing multispecies marine reserves and stress that an appropriate management regime is crucial for the success of the reserve, in particular to promote compliance. •This is the first study on ecological effects of MPAs in the Azores archipelago.•Positive effects were limited to resident, large bodied fishes in well complied MPAs.•Deeper, complex habitat also promoted higher fish abundance across ecological traits.•The Azorean MPA network needs better designed and complied multispecies MPAs.