Temporal dynamics of demersal chondrichthyan species in the central western Mediterranean Sea: The case study in Sardinia Island

Marongiu, Martina Francesca; Porcu, Cristina; Bellodi, Andrea; Cau, Alessandro; Cuccu, Danila; Mulas, Antonello; Follesa, María Cristina

doi:10.1016/j.fishres.2017.04.001

Cited by 35 publications

(32 citation statements)

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“…A previous study conducted by Bertrand et al (2000) involving almost the same GSAs sa those analysed in this work pointed out that the most widespread species in the basin were Scyliorhinus canicula, Galeus melastomus and Etmopterus spinax among sharks, Raja clavata, Raja miraletus, Raja asterias and Torpedo marmorata among batoids, and Chimaera monstrosa. From our results, the most frequent and abundant species all around the basin are S. canicula, G. melastomus and E. spinax among sharks and R. clavata and R. miraletus among batoids, partly confirming the findings of Bertrand et al (2000) and other previous data present in literature for the western (Barría et al 2015, Ramírez-Amaro et al 2015, Marongiu et al 2017), central (e.g. Jukić-Peladić et al 2001, Bottari et al 2014) and eastern (Tserpes et al 2013) Mediterranean.…”

Section: Discussionsupporting

confidence: 91%

“…-Number of MEDITS hauls carried out annually during the period 2012-2015 and analysed in the present study by geographical sub-area (GSA) of the General Fisheries Commission for the Mediterranean, country and depth strata (total, 10-800 m; continental shelf, 10-200 m; slope, 201-800 m). Area Total hauls Shelf hauls Slope hauls 1 Spain Northern Alboran 187 71 116 5 Spain Balearic Islands 218 142 76 6 Spain Northern Spain 388 282 106 7 France Gulf of Lions 66 55 11 8 France Corsica 23 10 13 9 Italy Ligurian, northern and central Tyrrhenian seas 120 55 65 10 Italy Central and southern Tyrrhenian seas 70 29 41 11 Italy Sardinian seas 101 63 38 16 Italy Strait of Sicily 120 55 65 17 Italy ish (Guijarro et al 2012, Barría et al 2015, Ramírez-Amaro et al 2015, Italian (Follesa et al 2011, Ligas et al 2013, Marongiu et al 2017 and Greek waters (Maravelias et al 2012, Tserpes et al 2013). These studies have been carried out on the northern Mediterranean coast and very few have been carried out on the southern coast off Africa (e.g.…”

Section: Variabilidad Espacial De Chondrichthyes En El Norte Del Medimentioning

confidence: 99%

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Spatial variability of Chondrichthyes in the northern Mediterranean

et al. 2020

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Thanks to the availability of the MEDITS survey data, a standardized picture of the occurrence and abundance of demersal Chondrichthyes in the northern Mediterranean has been obtained. During the spring-summer period between 2012 and 2015, 41 Chondrichthyes, including 18 sharks (5 orders and 11 families), 22 batoids (3 orders and 4 families) and 1 chimaera, were detected from several geographical sub-areas (GSAs) established by the General Fisheries Commission for the Mediterranean. Batoids had a preferential distribution on the continental shelf (10-200 m depth), while shark species were more frequent on the slope (200-800 m depth). Only three species, the Carcharhiniformes Galeus melastomus and Scyliorhinus canicula and the Torpediniformes Torpedo marmorata were caught in all GSAs studied. On the continental shelf, the Rajidae family was the most abundant, being represented in primis by Raja clavata and then by R. miraletus, R. polystigma and R. asterias. The slope was characterized by the prevalence of G. melastomus in all GSAs, followed by S. canicula, E. spinax and Squalus blainville. Areas under higher fishing pressure, such as the Adriatic Sea and the Spanish coast (with the exception of the Balearic Islands), show a low abundance of chondrichthyans, but other areas with a high level of fishing pressure, such as southwestern Sicily, show a high abundance, suggesting that other environmental drivers work together with fishing pressure to shape their distribution. Results of generalized additive models highlighted that depth is one of the most important environmental drivers influencing the distribution of both batoid and shark species, although temperature also showed a significant influence on their distribution. The approach explored in this work shows the possibility of producing maps modelling the distribution of demersal chondrichthyans in the Mediterranean that are useful for the management and conservation of these species at a regional scale. However, because of the vulnerability of these species to fishing exploitation, fishing pressure should be further incorporated in these models in addition to these environmental drivers.

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Section: Discussionsupporting

confidence: 91%

Section: Variabilidad Espacial De Chondrichthyes En El Norte Del Medimentioning

confidence: 99%

Spatial variability of Chondrichthyes in the northern Mediterranean

et al. 2020

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“…The no increase in fishing effort of the bottom trawl, jointly with its displacement to deep waters, must be the basis for the current stability and recovery shown by sharks and batoids on the continental shelf. This shift in trawl activity has also been suggested to explain the recent stability observed in demersal chondrichthyans off Sardinia 44 , in the central western Mediterranean. Similarly, in the north-east Atlantic the progressive reduction of fishing pressure has resulted in the recovery of certain stocks, including S. canicula [45][46][47] .…”

Section: Discussionmentioning

confidence: 61%

The diversity of recent trends for chondrichthyans in the Mediterranean reflects fishing exploitation and a potential evolutionary pressure towards early maturation

Ramírez‐Amaro

Ordines

Esteban

et al. 2020

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Chondrichthyans are a vulnerable group that has been overexploited for almost half a century in the Mediterranean. Since in this area most chondrichthyans are rarely incorporated into international statistics, the impact of fishing on their populations is difficult to assess. Here, we evaluate temporal trends in order to understand the recent history of chondrichthyans in the western Mediterranean. Fishery-independent data were obtained from scientific surveys carried out from 1994 to 2015 in three geographical sub-areas. Our results reflect fairly stable populations in terms of diversity, with some increase in density and standardized biomass of some species dwelling on the continental shelf, and even for some species dwelling on the slope. In contrast, decreasing trends were observed in some deep-water species. This can be explained by the reduction of the trawling effort on the continental shelf over the last few decades, and the shift of the fleet towards deep waters, along with the greater resilience displayed by some species. Furthermore, a decreasing trend in maturity of Scyliorhinus canicula was detected, suggesting an evolutionary response to overfishing. These results improve scientific knowledge for developing true adaptive management in the Mediterranean that will implement measures to strengthen or initiate the recovery of chondrichthyans. Marine ecosystems are under pressure from overfishing, habitat degradation and climate change which have altered the populations of most of their species 1,2 , especially chondrichthyans (sharks, rays and chimaeras), due to their low population resilience 3-5. Global chondrichthyan landings, reported to the Food and Agriculture Organization of the United Nations (FAO), increased over 200% from 1950 to the peak year in 2003 and subsequently dropped almost 15% by 2011 6. In the Mediterranean, the temporal evolution of chondrichthyan landings has gone through three stages: a development phase at the beginning of the 1950s; followed by intense fishing pressure from the mid 1950s to 1970, corresponding to the exploited phase; and a decreasing trend from 1970 to recent years, indicating an overexploited status (Fig. 1), such as has been reported for most demersal and pelagic bony fish and shellfish stocks a decade later during the eighties 7-10. This earlier overexploitation in chondrichthyans is to be expected due to their low resilience. Studies of long time series of chondrichthyan catches conducted in several areas of the Mediterranean have also shown decreasing trends over the last few decades 11-14. Furthermore, there is evidence that Mediterranean chondrichthyans have declined in diversity. At present, several species such as Dipturus batis (recently split into two cryptic species, D. cf. flossada and D. cf. intermedia 15 , Pristis

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“…Our work aims to analyse the trophic ecology and the resource partitioning among seven sympatric elasmobranch species inhabiting the Sardinian continental shelf (centralwestern Mediterranean) (Marongiu et al 2017). Since these species exploit the same habitats, we hypothesized that strong resource partitioning facilitates coexistence, minimizing trophic niche overlap.…”

Section: Introductionmentioning

confidence: 99%