Acta Adriatica, Vol. 63 No. 1, 2022.
Original scientific paper
https://doi.org/10.32582/aa.63.1.10
Occurrence of bluntnose sixgill shark, Hexanchus griseus (Bonnaterre, 1788) in the Gulf of Trieste (northern Adriatic) with particular reference to historical and contemporary records in the Adriatic Sea
Lorenc Lipej
; Marine Biology Station, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia
Domen Trkov
; Marine Biology Station, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia
Borut Mavrič
; Marine Biology Station, National Institute of Biology, Fornače 41, 6330 Piran, Slovenia
Tomaso Fortibuoni
; Istituto Superiore per le Protezione e la Ricerca Ambientale (ISPRA), Via Ca‘ Fornacetta 9, 40064 Ozzano dell‘Emilia, Bologna, Italy
Nicola Bettoso
; Agenzia Regionale per la Protezione dell ́Ambiente del Friuli Venezia Giulia, Via A. La Marmora, 13, 34139, Trieste, Italy
Daša Donša
; Faculty for Natural Sciences and Mathematics and Faculty of Arts, University of Maribor, Koroška 160, 2000 Maribor, Slovenia
Danijel Ivajnšić
Abstract
A specimen of a sixgill bluntnose shark, Hexanchus griseus (Bonnaterre, 1788), was caught 1.5
NM north of Cape Ronek (Izola, Slovenia) in a fishing net for large-sized flatfish (such as turbot) on
28 January 2018. Three other older cases of catch of sixgill bluntnose sharks were recorded in Slo-
venia and the Gulf of Trieste. Among these, the finding of the specimen in the Lagoon of Marano and
Grado is unusual although there are reported cases of sixgill bluntnose sharks in rivers. An analy-
sis of the available data on the bluntnose sixgill shark in the Adriatic Sea, obtained from different
published papers, social media and other sources, was done to understand whether the occurrence
of H. griseus in the northern Adriatic differs from other parts. A generalised linear model (GLM)
approach revealed that larger specimens are more frequently sighted across the Adriatic Sea, while
in the Northern Adriatic part, significantly smaller specimens (juveniles) were recorded in compari-
son to the Central and Southern parts. It seems that the bluntnose sixgill shark is not in conjunction
with a common large shark decreasing trend across the whole Mediterranean Sea.
Keywords
Chondrichthyes; Hexanchus griseus; Slovenia; occurrence; Adriatic Sea
Hrčak ID:
281139
URI
Publication date:
8.8.2022.
Visits: 1.253 *