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RESEARCH ARTICLE

Biological parameters and spatial segregation patterns in sharks from the North Aegean Sea, Greece

Dimitrios Karampetsis https://orcid.org/0000-0002-7402-9602 A B # , Chrysoula Gubili https://orcid.org/0000-0002-0866-6259 B # * , Konstantinos Touloumis https://orcid.org/0000-0002-8560-7391 B , Angeliki Adamidou B , Stelios Triantafillidis B , Athanasios Evangelopoulos B , Ioannis E. Batjakas A , Nikolaos Kamidis B and Emmanouil Koutrakis B
+ Author Affiliations
- Author Affiliations

A Department of Marine Sciences, University of the Aegean, University Hill, GR-81100 Mytilene, Greece.

B Hellenic Agricultural Organisation-DIMITRA, Fisheries Research Institute, Nea Peramos, GR-64007 Kavala, Greece.

* Correspondence to: c.gubili@inale.gr
# These authors contributed equally to this paper

Handling Editor: Colin Simpfendorfer

Marine and Freshwater Research 73(11) 1378-1392 https://doi.org/10.1071/MF22079
Submitted: 7 March 2022  Accepted: 24 August 2022   Published: 27 September 2022

© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing

Abstract

Context: Sharks are frequently caught as bycatch in trawl fisheries in the North Aegean Sea. However, very little information exists on their biology and ecology in the area.

Aims: Biological parameters and spatial segregation of sharks in relation to size class, sex, depth and geographic location were examined.

Methods: Morphological characteristics and generalised additive models were used to explore biological traits and aggregating behaviour respectively, by using data from the Mediterranean International Trawl Survey between 2014 and 2021.

Key results: Overall, 7761 specimens were measured, with Scyliorhinus canicula, Galeus melastomus and Squalus blainville being the most common species. Scyliorhinus canicula was found in shallow coastal waters, whereas the remaining species were detected in deeper waters.

Conclusions: Females were larger and heavier than males and the weight–length relationships corroborated size differences between sexes in all species, whereas allometric growth did not share the same patterns as those from the Mediterranean Sea. Generalised additive models showed that the distribution of dominant species is bathymetric and geographically dependent. Additionally, the depth and geographic segregation patterns are highly associated with ontogeny and not sex.

Implications: These findings highlighted the importance of incorporating elasmobranch behavioural characteristics in the poorly developed management regulations in the North Aegean Sea.

Keywords: aggregation, distribution, eastern Mediterranean, elasmobranchs, general additive models, GSA22, MEDITS, reproductive biology.


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