Life history aspects of two species of the <i>Squalus</i> genus in the Eastern Ionian Sea

Anastasopoulou, Aikaterini; Mytilineou, Chryssi; Makantasi, P.; Smith, Christopher J.; Kavadas, Stefanos; Lefkaditou, Eugenia; Papadopoulou, Nadia

doi:10.1017/s0025315416001818

Cited by 10 publications

(4 citation statements)

References 35 publications

(73 reference statements)

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“…Indeed, recent studies (e.g. Anastasopoulou et al 2018) highlight that S. acanthias showed a limited geographic distribution in the past, suggesting an inaccurate classification of these two species.…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%

Spatial variability of Chondrichthyes in the northern Mediterranean

et al. 2020

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“…The size threshold was 100 cm TL for C. conger (e.g. Mazouz & Abi-Ayad, 2015), 35 cm TL for G. melastomus (Colloca et al , 2013), 20 cm for H. dactylopterus (Mendonça et al , 2006), 45 cm TL for M. merluccius (Piñeiro & Saínza, 2003; Recasens et al , 2008), 30 cm TL for P. bogaraveo (Mytilineou et al , 2013), 35 cm TL for P. blennoides (Glavić et al , 2014) and 55 cm TL for S. blainville (Anastasopoulou et al , 2017).…”

Section: Methodsmentioning

confidence: 99%

Crustacean prey in the diet of fishes from deep waters of the Eastern Ionian Sea

et al. 2018

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The gut analysis of 26 fish species caught in the deep waters of the Eastern Ionian Sea showed that crustaceans were a substantial resource for fish found in deep- water environments, comprising 37 crustacean taxa. Among all species examined, 77% included crustaceans in their guts. Dendrobranchiata/Caridea shrimps were the most frequent crustacean prey found in the guts of almost all examined fishes, with high values of relative abundance (N%). Season (summer, autumn) and fish behaviour (demersal, benthic) were not found to affect the diet of the examined fish species. Galeus melastomus could be considered to be a separate case showing the most diverse diet comprising all the crustacean groups. Differences in the proportion of the main crustacean categories consumed by the examined fish species were observed. The low richness and preference towards specific crustacean taxa or different crustacean species could be considered as an indication of interspecific competition for the same food resource in the oligotrophic waters of the Eastern Mediterranean. The occurrence of different crustacean taxa in the gut of some species through the analysed seasons, could be related to differences in prey availability or to selective preference for certain prey which in turn could be linked to different energetic requirements for growth and reproduction of predators.

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“…The reason for this replacement between those sharks could be related to taxonomic problems afflicting the Squalus genus in different areas of the Mediterranean [38,84]. Indeed, recent studies [53] highlight that S. acanthias showed a limited geographic distribution in the past, suggesting an inaccurate classification of these two species [90].…”

Section: Geographic Distributionmentioning

confidence: 99%

Overview of the Genus Squalus in the Mediterranean Sea

Marouani¹,

Karaa²,

Jarboui³

2023

Sharks - Past, Present and Future

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In the Mediterranean Sea, in addition to the two historically known species belonging to the Squalus genus (Squalus blainville and Squalus acanthias), a third species, Squalus megalops, has been reported. This last specie is a subject of debate between authors. S. acanthias is quite distinct from the other species of the genus Squalus, while S. blainville and S. megalops are very similar morphologically. This similarity has resulted in considerable confusion over their taxonomy. The lack of a well-preserved holotype for S. blainville, misidentifications in databases and in the literature, description, and figure of Risso (1827) not conforming to any known species of Squalus are impediments to the proper taxonomic identification and the potential revision of the genus. This chapter aims to clarify the state of the species of the genus Squalus in the Mediterranean Sea, taking into account all the studies carried out on this subject.

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Life history aspects of two species of the Squalus genus in the Eastern Ionian Sea

Cited by 10 publications

References 35 publications

Spatial variability of Chondrichthyes in the northern Mediterranean

Spatial variability of Chondrichthyes in the northern Mediterranean

Crustacean prey in the diet of fishes from deep waters of the Eastern Ionian Sea

Overview of the Genus Squalus in the Mediterranean Sea

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