Abstract
Since July 2019, Gyaros island in the central Aegean Sea, enjoys the status of a partial Marine Protected Area (MPA), allowing for exploitation by small-scale fishers following specific spatio-temporal restrictions. The need for assessing the effectiveness of the MPA in the future, led MAVA Foundation to fund a knowledge survey project aiming to serve as a baseline for future reference. A series of experimental fishing surveys took place with static nets, the outcomes of which are presented herein. From June 2018 to September 2020, a series of 8 fishing excursions with a total of 40 experimental fishing sets with bottom static nets were realized in 5 set locations around Gyaros island, inside the MPA protection zone. A total of 75 species were identified; the most abundant species, in terms of biomass, being: parrotfish-Sparisoma cretense, red scorpionfish-Scorpaena scrofa, common spiny lobster-Palinurus elephas, red porgy-Pagrus pagrus, little tunny–-Euthynnus alletteratus, Mediterranean moray-Muraena helena, lesser spotted dogfish -Scyliorhinus canicula, forkbeard-Phycis phycis, surmullet-Mullus surmuletus, common cuttlefish-Sepia officinalis and common Pandora-Pagellus erythrinus. A comparison with similar data in adjacent areas outside the MPA allowed for assessing the effectiveness of the MPA based on four indicators: species diversity index, species relative biomass index, key predator species abundance, and alien fish abundance. Based solely on the experimental fishing trials, the MPA seems to be functioning, since both species diversity and abundance were higher within the protected area. However, its performance may still not be considered as optimal, as this is indicated by the large proportion of undersized key predators (e.g. groupers), although more abundant and larger than the ones residing outside the MPA.
Highlights
Marine Protected Areas (MPAs) are considered one of the easiest management strategies to enforce, since they do not require setting up a maze of regulatory restrictions
A total of 75 species/taxa have been identified in the surveys, the most abundant in terms of biomass being: parrotfish-Sparisoma cretense, red scorpionfish-Scorpaena scrofa, common spiny lobster-Palinurus elephas, red porgy-Pagrus pagrus, little tunny–Euthynnus alltetteratus, Mediterranean moray-Muraena helena, lesser spotted dogfish-Scyliorhinus canicula, forkbeard-Phycis phycis, Surmullet-Mullus surmuletus, common cuttlefish-Sepia officinalis and common pandora-Pagellus erythrinus
The red porgies were associated with maerl beds, they resided in deeper waters (Fig 6 –mid right)
Summary
Experimental fishing surveys have been carried out in five fixed locations around the island (Fig 2 and Table 1). Based on the aforementioned dataset, hosted in the HCMR database [8], we have analysed the data of the small-scale fishery (SSF) catches in the vicinity of Gyaros island. These data are based on monitoring the fishing activities by observers stationed on board fishing vessels. The marine region (37o34’20”– 37o38’10” North, 24o38’12”–24o45’40” East) was gridded in a spatial resolution of 0.01 x 0.01 of a degree, concluding to a total of 180 grid cells (land excluded) Each one of these cells was assigned the corresponding values for each of the model parameters (e.g.: depth, substrate type, latitude, longitude). All diversity analyses were conducted using the PRIMER-6 software package [17]
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