Special Issue "Sharks and Skates: Ecology, Distribution and Conservation"

A special issue of Animals (ISSN 2076-2615). This special issue belongs to the section "Ecology and Conservation".

Deadline for manuscript submissions: 30 April 2022.

Special Issue Editor

Dr. Martina Francesca Marongiu
E-Mail Website
Guest Editor
Dipartimento di Scienze della Vita e dell’Ambiente, University of Cagliari, Via T. Fiorelli 1, 09126 Cagliari, Italy
Interests: cartilaginous fish; conservation biology and ecology; reproductive biology; macro and micro-anatomy; histology

Special Issue Information

Dear Colleagues,

Chondrichthyans (sharks, skates, rays and chimaeras) represent one of the oldest and most ecologically various vertebrate lineages. This group of predators occupy the top of aquatic food webs and play an important functional role in the control of coastal and oceanic ecosystem structure and function. However, nowadays, overfishing and habitat degradation are altering their populations leading to a worrisome decline of these species worldwide because of their low resilience. Moreover, data on the stock status of this important resource remain still poor or non-existent, which is due to a problematic taxonomy (e.g., misidentification issues).

In this Special Issue, we invite contributions that investigate the life histories of Chondrichthyans (e.g., reproduction, age and growth), trophic ecology, genetic information and updated data on their distribution in order to collect information that is helpful to develop conservation plans for these marine predators.

Topics may include, but are not limited to, species inhabiting coastal waters, transitional waters (e.g., freshwaters), oceans, deep seas, pelagic and bottom environments.

Dr. Martina Francesca Marongiu
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Animals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • cartilaginous fish
  • conservation biology and ecology
  • population genetics
  • management
  • oceans
  • shallow waters
  • deep sea
  • freshwaters

Published Papers (2 papers)

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Research

Article
Batoid Abundances, Spatial Distribution, and Life History Traits in the Strait of Sicily (Central Mediterranean Sea): Bridging a Knowledge Gap through Three Decades of Survey
Animals 2021, 11(8), 2189; https://doi.org/10.3390/ani11082189 - 23 Jul 2021
Viewed by 767
Abstract
Batoid species play a key role in marine ecosystems but unfortunately they have globally declined over the last decades. Given the paucity of information, abundance data and the main life history traits for batoids, obtained through about three decades of bottom trawl surveys, [...] Read more.
Batoid species play a key role in marine ecosystems but unfortunately they have globally declined over the last decades. Given the paucity of information, abundance data and the main life history traits for batoids, obtained through about three decades of bottom trawl surveys, are presented and discussed. The surveys were carried out in two areas of the Central Mediterranean (South of Sicily and Malta Island), in a timeframe ranging from 1990 to 2018. Excluding some batoids, the abundance trends were stable or increasing. Only R. clavata, R. miraletus, and D. oxyrinchus showed occurrence and abundance indexes notable enough to carry out more detailed analysis. In particular, spatial distribution analysis of these species highlighted the presence of two main hotspots in Sicilian waters whereas they seem more widespread in Malta. The lengths at first maturity (L50) were 695 and 860, 635 and 574, and 364 and 349 mm total length (TL), respectively, for females and males of D. oxyrinchus, R. clavata, and R. miraletus. The asymptotic lengths (L∞) and the curvature coefficients (K) were 1365 and 1240 (K = 0.11 and 0.26), 1260 and 1100 (K = 0.16 and 0.26), and 840 and 800 mm TL (K = 0.36 and 0.41), respectively, for females and males of D. oxyrinchus, R. clavata, and R. miraletus. The lack of detailed quantitative historical information on batoids of Sicily and Malta does not allow to analytically judge the current status of the stocks, although the higher abundance of some species within Malta raises some concern for the Sicilian counterpart. In conclusion, suitable actions to protect batoids in the investigated area are recommended. Full article
(This article belongs to the Special Issue Sharks and Skates: Ecology, Distribution and Conservation)
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Article
Vulnerability Assessment of Pelagic Sharks in the Western North Pacific by Using an Integrated Ecological Risk Assessment
Animals 2021, 11(8), 2161; https://doi.org/10.3390/ani11082161 - 21 Jul 2021
Viewed by 805
Abstract
The vulnerability of 11 pelagic shark species caught by the Taiwanese coastal and offshore longline fisheries in the western North Pacific were assessed by an ecological risk assessment (ERA) and 10 of the 11 species was assessed by using an integrated ERA developed [...] Read more.
The vulnerability of 11 pelagic shark species caught by the Taiwanese coastal and offshore longline fisheries in the western North Pacific were assessed by an ecological risk assessment (ERA) and 10 of the 11 species was assessed by using an integrated ERA developed in this study. The intrinsic rate of population growth was used to estimate the productivity of sharks, and the susceptibility of sharks was estimated by the multiplication of the catchability, selectivity, and post-capture mortality. Three indices namely, the IUCN Red List category, the body weight variation trend, and the inflection point of population growth curve coupled with ERA were used to conduct an integrated ERA. The results indicated that the scalloped hammerhead is at the highest risk (group 1), followed by the silky shark, and the spinner shark at high risk (group 2). The bigeye thresher, and sandbar shark fall in group 3, the smooth hammerhead falls in group 4, and the shortfin mako, pelagic thresher, oceanic whitetip, and dusky shark fall in group 5. Rigorous management measures for the species in groups 1 and 2, setting total allowable catch quota for group 3, and consistent monitoring schemes for groups 4 and 5 are recommended. Full article
(This article belongs to the Special Issue Sharks and Skates: Ecology, Distribution and Conservation)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Passive Prey Discrimination in Surface Predatory Behaviour of Bait-Attracted White Sharks from Gansbaai, South Africa

Authors: Micarelli Primo1*, Chieppa Federico1, Pacifico Antonio 1,2, Reinero Francesca Romana1

Affiliation: 1 Sharks Studies Center – Scientific Institute, 58024 Massa Marittima (Italy)

2 Department of Political Science and CEFOP-LUISS, LUISS Guido Carli University, 00197 Rome (Italy)

Abstract: Between the years 2008 and 2013, six annual research expeditions were carried out at Dyer Island (Gansbaai, South Africa) to study the surface behaviour of white sharks in the presence of two passive preys: tuna bait and seal shaped decoy. Sightings occurred from a commercial cage-diving boat during 247 hours of effort; 250 white sharks, with a mean total length (TL) of 308 cm, were observed. 166 of them did at least one or more interactions, for a total of 240 interactions with bait and seal shaped decoy. Both mature and immature sharks preferred to prey on seal shaped decoy, and this was probably due to the dietary shift that occurs in white sharks whose TL varies between 200 cm and 340 cm. Because it is widely confirmed that white sharks change their diet from a predomi-nantly piscivorous juvenile diet to a mature marine mammalian diet, it is possible that Gansbaai may be a hunting training area and that sharks show a discriminate food choice, a strategy that was adopted by the majority of specimens thanks to their ability to visualize the energetically richer prey, after having been attracted by the odorous source represented by the tuna bait.

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Title: Change in Diversity and Abundance Habitat-Related of the Carti-Laginous Fishes in the Central Mediterranean Sea

Authors: Letizia Sion 1,2*

Affiliation: 1 Department of Biology, University of Bari Aldo Moro, Via Orabona, 4 - 70125 Bari, Italy;

2 CoNISMa, Piazzale Flaminio, 9 - 00196 Roma, Italy

Abstract: The cartilaginous fishes represent a valuable natural capital within the marine ecosystems as most of them fill the upper levels of aquatic food webs with possible top-down control over medium-level consumers. Due to their K-selected life strategy, these species are particularly vulnerable to the human activities and many of them are at risk of extinction. Although sharks and skates play a key role in the biological communities, the effects of their decline on the marine ecosystem, due mostly to fishing activity, are still poorly known. Considering data coming mainly by scientific surveys carried out in the last thirty years, the authors provide information on the species diversity and fluctuations of abundance of sharks and skates caught on the fishing ground of the north-western Ionian Sea, focusing the analysis on the changes of the species composition, distribution variable vulnerability and exposure to fishing of the different species. In addition, recent acquisitions on the distribution and abundance of elasmobranchs in Vulnerable Marine Eco-systems (VMEs) (cold-water coral habitats and canyons) of the north-western Ionian and southern Adriatic Sea are reported. Since these habitats, less accessible to fishing, can provide a natural refuge for these vulnerable species, large-scale connected marine protected areas of high sea can be a potential management option for the cartilaginous fish conservation.

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Title: A Taxonomic Survey of Oviducal Glands in Chondrichthyes: A Comparative Overview of Microanatomy in the Two Reproductive Modes

Authors: Martina Francesca Marongiu1,2*†, Cristina Porcu1,2*†, Noemi Pascale1, Andrea Bellodi1,2, Alessandro Cau1,2, Antonello Mulas1,2, Paola Pesci1,2, Riccardo Porceddu1, Maria Cristina Follesa1,2

Affiliation: 1 Dipartimento di Scienze della Vita e dell’Ambiente, Università degli Studi di Cagliari, Via Tommaso Fiorelli 1, 09126 Cagliari, Italy.

2 Consorzio Nazionale Interuniversitario per le Scienze Mare (CoNISMa), Piazzale Flaminio 9, 00196 Roma, Italy.

† The authors contributed equally to this work.

Abstract: More than half of Chondrichthyans in the Mediterranean Sea are threatened because of overfishing. In this context, knowledge of the overall process of reproduction by investigating the fate of spermatozoa in the female reproductive tract would be useful to better understand the ecology and population dynamics of these species. The goal of this study is to provide a taxonomic survey of oviducal glands (OGs), responsible for producing egg coats and sperm storage, in some demersal oviparous and viviparous Chondrichthyans living in the Basin. The microanatomy of the OGs is documented for three oviparous and four aplacental viviparous species, using morphological, histological and histochemical remarks. Differences in gland size and tubules length between oviparous and vivip-arous was observed. The luminal profile of the gland increases in oviparous species to facilitate the production of the secretory material for producing the eggcases in contrast to that of live-bearing species characterized by a glandular volume breakdown. Sperm storage was observed in one oviparous shark and in all viviparous species investigated (all dwelling deep environments) for the first time and it can be considered an adaptive response to mating behaviour, having particular benefits in the relatively low productivity of deep-sea environments.

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