Condition and survival rates of the most frequently discarded deep-sea elasmobranchs from crustacean bottom trawl fisheries in the southern Portugal

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Dataset of the complete mitogenome of the deep-sea sailfin roughshark, Oxynotus paradoxus Frade, 1929

Publication . Matos, Ana; Gomes-dos-Santos, André; Graça Aranha, Sofia; Dias, Ester; Veríssimo, Ana; Teodosio, Maria; Figueiredo, Ivone; Castro, L. Filipe C．; Froufe, Elsa

Chondrichthyans comprise a diverse group of vertebrate species with extraordinary ecological relevance. Yet, multiple members of this evolutionary lineage are associated with sig-nificant extinction risk. The sailfin roughshark Oxynotus para-doxus is a deep-water benthic shark currently listed as vul-nerable due to population declines in parts of its range. Here we provide the first complete mitochondrial genome of O. paradoxus, comprising also the first record for the genus and family Oxynotidae. These data can facilitate future monitor-ing of the genetic diversity in this and related species. Ge-nomic DNA was extracted from O. paradoxus collected in the eastern North Atlantic off western Portugal (37.59 degrees N, 9.51 degrees W) and sent for Illumina Paired-End (2 x 150 bp) library con-struction and whole genome sequencing on a Novaseq60 0 0 platform. Trimmomatic (version 0.38) was used to remove adapters and MitoZ (version 3.4) to assemble and anno-tate the mitogenome. This mitogenome with 17 100 bp has a total of 38 genes, 13 of which are protein-coding genes, 23 transfer RNA genes, and 2 ribosomal RNA genes. Eight transfer RNAs and 1 protein-coding gene (NADH de-hydrogenase subunit 6, NAD6) are in the complementary strand. In the provided phylogenetic inference, with all avail-able and verified Squalomorphii mitogenomes, the four or-ders are well separated, and as expected, O. paradoxus is placed in the Squaliformes order. This data reinforces the need for more genomic resources for the Oxynotidae family.(c) 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

2024-02Journal article

Open access

A glimpse into the trophic ecology of deep‐water sharks in an important crustacean fishing ground

Publication . Graça Aranha, Sofia; Teodosio, MA; Baptista, Vânia; Erzini, Karim; Dias, Ester

Deep-water sharks are among the most vulnerable deep-water taxa because of their extremely conservative life-history strategies (i.e., late maturation, slow growth, and reproductive rates), yet little is known about their biology and ecology. Thus, this study aimed at investigating the trophic ecology of five deep-water shark species, the birdbeak dogfish (Deania calcea), the arrowhead (D. profundorum), the smooth lanternshark (Etmopterus pusillus), the blackmouth catshark (Galeus melastomus) and the knifetooth dogfish (Scymnodon ringens) sampled onboard a crustacean bottom-trawler off the south-west coast of Portugal. We combined carbon and nitrogen stable isotopes with RNA and DNA (RD) ratios to investigate the main groups of prey assimilated by these species and their nutritional condition, respectively. Stable isotopes revealed overall small interspecific variability in the contribution of different taxonomic groups to sharks' tissues, as well as in the origin of their prey. S. ringens presented higher delta N-15 and delta C-13 values than the other species, suggesting reliance on bathyal cephalopods, crustaceans and teleosts; the remaining species likely assimilated bathy-mesopelagic prey. The RD ratios indicated that most of the individuals had an overall adequate nutritional condition and had recently eaten. This information, combined with the fact that stable isotopes indicate that sharks assimilated prey from the local or nearby food webs (including commercially important shrimps), suggests a potential overlap between this fishing area and their foraging grounds, which requires further attention.

2023Journal article

Open access