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Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences
RESEARCH ARTICLE

Genetic characterisation of the spiny dogfish Squalus acanthias in the Adriatic Sea: evidence for high genetic diversity and an Atlantic–South Pacific origin

Romana Gračan A , Bojan Lazar B C , Sara Zupan B and Elena Bužan https://orcid.org/0000-0003-0714-5301 B D E
+ Author Affiliations
- Author Affiliations

A University of Zagreb, Faculty of Science, Department of Biology, Division of Zoology, Roosevelt Square 6, HR-10000 Zagreb, Croatia.

B University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technologies, Department of Biodiversity, Glagoljaška 8, SI-6000 Koper, Slovenia.

C Juraj Dobrila University of Pula, Marine Science Program, Zagrebačka 30, HR-52100 Pula, Croatia.

D Environmental Protection College, Trg mladosti 7, SI-3320 Velenje, Slovenia.

E Corresponding author. Email: elena.buzan@upr.si

Marine and Freshwater Research 72(1) 131-139 https://doi.org/10.1071/MF20046
Submitted: 12 February 2020  Accepted: 19 March 2020   Published: 19 May 2020

Abstract

Spiny dogfish Squalus acanthias is a widely distributed, highly migratory mesopredatory shark that is extremely sensitive to overexploitation. Because of unregulated targeted and incidental capture and a lack of enforceable management in the Mediterranean Sea, the spiny dogfish subpopulation has declined by at least 50% in the Mediterranean Sea over the past 75–105 years, and is regionally classified as endangered. In this study we sampled 124 spiny dogfish in the northern-most part of the Mediterranean (i.e. the Adriatic Sea) to: (1) assess levels of genetic diversity using 13 microsatellite loci and mitochondrial (mt)DNA (NADH dehydrogenase subunit 2 (ND2) gene); and (2) infer its evolutionary placement while assessing further possible genetic divergence across the Atlantic and Pacific Ocean basins based on ND2. Analysis of mtDNA revealed 12 unique haplotypes and a high level of genetic variation in the Mediterranean region, whereas results from microsatellite markers showed significant genetic heterogeneity and a fine-scale stock structuring involving both sexes. The findings support an Atlantic–South Pacific origin for the spiny dogfish in the Adriatic Sea, with little or no present-day connectivity with the Atlantic population. Consequently, this commercially exploited and regionally endangered coastal shark in the Adriatic Sea should be considered as a separate management unit, with implementation of regional protective management plans.

Additional keywords: conservation, elasmobranchs, population connectivity.


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