DOI: 10.5061/dryad.05qfttf0k
title: Data from: Extending full protection inside existing marine protected areas or reducing fishing effort outside can reconcile conservation and fisheries goals

description: 1. Most fish stocks worldwide are fished at maximum sustainable yield
 (MSY) or overfished, as many fisheries management strategies have failed
 to achieve sustainable fishing. Identifying effective fisheries management
 strategies has now become urgent. 2. Here, we developed a
 spatially-explicit metapopulation model accounting for population
 connectivity in the north-western Mediterranean Sea, and parameterized it
 for three ecologically and economically important coastal fish species:
 the white seabream Diplodus sargus, the two-banded seabream Diplodus
 vulgaris and the dusky grouper Epinephelus marginatus. 3. We used the
 model to assess how stock biomass and catches respond to changes in
 fishing mortality rate (F) and in the size of fully protected areas within
 the existing system of multiple-use marine protected areas (MPAs). For
 each species, we estimated MSY and the corresponding values of stock
 biomass (BMSY) and fishing mortality rate (FMSY), providing crucial
 reference points for the assessment of fisheries management. 4. D. sargus
 is currently in low overfishing, while D. vulgaris and E. marginatus are
 in high overfishing. Stock recovery to BMSY for the last two species
 requires a reduction of current F around 50%. This would guarantee an
 increase in both stock biomass (around 50 and 75% for D. vulgaris and E.
 marginatus, respectively) and catch (around 15 and 30%) after a transient
 time of ~15–30 years. Alternatively, doubling the size of fully protected
 areas over fishable areas within the existing network of MPAs would lead
 to positive conservation effects for all three species without
 substantially affecting the overall productivity of the fishery and the
 total economic value of the catch. 5. Synthesis and applications. We
 provide the first assessment of stock status for three coastal species in
 the north-western Mediterranean and evaluate the ecological and fisheries
 outcomes of different management strategies. Extending full protection
 inside existing multiple-use marine protected areas or reducing fishing
 effort outside can deliver both conservation and fisheries benefits.
description: Data on population density for the three fish species were
 collected in June–July 2017 across the north-western Mediterranean, at
 sites characterized by three different protection levels: fully protected
 (no-take zone), partially protected (buffer zone) and unprotected (outside
 MPAs). Data were collected via underwater visual census (UVC) along
 instantaneous strip transects of 25×5 m. Censuses were performed on rocky
 substrates where other substrate types, like sand or seagrass, generally
 represented &lt;10% in cover (both within and around transects).
 Population density data collected at different sites were averaged over a
 grid with a 1/16° resolution (keeping different protection levels
 distinct). In addition, a long-term time series was collected within the
 Tavolara MPA (Sardinia, Italy), where population density was assessed via
 UVC between 2005 and 2016.
description: The first dataset is contained in the files NWMed_xx.csv, where
 xx indicates the species (DS: <i>Diplodus sargus</i>; DV:
 <i>Diplodus vulgaris</i>; EM: <i>Epinephelus
 marginatus</i>). Each file reports longitude and latitude of the
 centre of the grid cell, level of protection (FP: fully protected; PP:
 partially protected; UP: unprotected), and population density
 (individuals/m<sup>2</sup>). The second dataset is contained
 in the files Tavolara_xx.csv, which report year, level of protection and
 population density for each species (where xx is, again, the acronym of
 the species).