This study evaluates the fishing pressure exerted by the most common recreational and professional, small-scale fishing practices on vulnerable target and bycatch species in coastal and offshore waters of the western Mediterranean. By combining multiple data sources, we assembled a unique dataset on catches at multiple sites in these areas by recreational (RF) and small-scale fisheries (SSF), covering the period from 1997 to 2015. Furthermore, a framework with which to identify the vulnerable species among all the species caught is provided; it is based on the IUCN Red List, international conventions for the protection of flora and fauna, the Habitats Directive and the intrinsic vulnerability index of marine fish. Overall, about a quarter of exploited species targeted by SSF and RF in coastal waters were vulnerable, making up nearly 50% of the total SSF catch and nearly 20% of the total recreational catch. In offshore waters, 100% of the RF and SSF catch was made up of vulnerable species. Among the species caught as bycatch in both areas by SSF and RF, there was a total of 27 vulnerable vertebrate species, which included birds, cetaceans, elasmobranchs and sea turtles. Our results highlight the need to differentiate between different fishing methods or gears when studying the fishing impacts on vulnerable species. The results also indicate that, although RF and SSF are often considered to have a relatively low ecological impact, a range of different fishing methods are affecting vulnerable species in coastal or offshore waters in the western Mediterranean Sea, be they targeted or taken unintentionally as bycatch.
Pelagic larval duration (PLD) and trace elements in otoliths provide basic information to investigate the dispersal history of marine fishes. Due to the paucity of such information in the Mediterranean region, we assessed PLD, hatching and settlement duration and timing, and otolith microelemental composition of the White Sea bream (Diplodus sargus sargus) from multiple locations (hundreds of kilometers from each other) along the Italian coast (Mediterranean Sea). Otoliths were read to assess PLD and analyzed by a laser ablation inductively coupled plasma mass spectrometer in the core, larval and juvenile regions. PLD ranged from ∼14 to 17 days and significantly changed among locations, similarly to hatching (temporal windows of 10-24 days) and settlement (8-22 days) duration and timing, and microelemental fingerprints. These results show (1) a non-negligible large-scale variability in juvenile fish traits and otolith chemistry ever tested before for any Mediterranean fish; (2) the usefulness to properly estimate those traits and chemical features that may help shed light on spatial patterns of population connectivity and dispersal of marine fishes.
Rocky banks (i.e. sea mountain-like structures rising from the sea bottom) are hard substrate habitats of high socio-economic value (e.g. for fishermen and divers) and ecological relevance as they often host unusually high density of fish. Here we tested whether the response of fish assemblages to protection (i.e. related to the presence of a Marine Protected Area (MPA)) in rocky banks is comparable with the response of rocky reefs dropping from the coast (hereafter called ‘coastal rocky substrates’), and whether there are differences between fish assemblages associated with protected and unprotected rocky banks. Fish assemblages were assessed in shallow and deep coastal rocky substrates, and in rocky banks, in unprotected and protected conditions at a Mediterranean MPA in north-east Sardinia in August 2007 and 2008. Whole fish assemblage structures (in terms of biomass) differed between protected and unprotected conditions in both study years. Fish assemblages at rocky banks, in addition, differed from those associated with coastal rocky substrates. Total fish biomass (summing contribution of all species) was higher under protected than unprotected condition in 2007, while species richness and total fish density did not demonstrate any significant change related to protection. The responses to protection displayed by the target species Epinephelus marginatus and Diplodus sargus were clear especially in terms of greater frequency of large-sized specimens in both study years. Biomass of E. marginatus in 2007 and density of D. sargus in 2007 and 2008 were significantly higher in protected than unprotected conditions, especially in protected rocky banks. This study emphasizes the ecological and socio-economic role of protection and the potential role of rocky banks within management/conservation programmes in the Mediterranean Sea.
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