Hexanchus griseus (Bonnaterre, 1788)

Iglésias, Samuel P., Bergot, Patricia, Breton, Pascal, Brunelle, Stéphanie, Camusat, Mathieu, Causse, Romain, Charbonnel, Éric, Chevaldonné, Pierre, Cordier, Yves, Cosquer, Paul, Cuillandre, Jean-Pierre, Curd, Amelia, Dubas, Rémy, Duhau, Muriel, Derrien-Courtel, Sandrine, Devique, Gabriel, Dixneuf, Stéphane, Duhamel, Erwan, Farque, Pierre-André, Francour, Patrice, Fontana, Yann, Gamon, Adelaïde, Gicqueau, Charly, Goascoz, Nicolas, Hassani, Sami, Jadaud, Angélique, Kopp, Dorothée, Lamour, Laure, Bris, Sylvain Le, Lévèque, Laurent, Liger, Pablo, Lorance, Pascal, Louisy, Patrick, Maran, Vincent, Méhault, Sonia, Metral, Luisa, Morin-Repinçay, Alizée, Mouchel, Olivier, Pere, Anthony, Quéro, Jean-Claude, Renoult, Julien P., Roche, François, Schweyer, Livier, Spitz, Jérôme, Thiriet, Pierre & Thomas, Wilfried, 2020, French ichthyological records for 2018, Cybium 44 (4), pp. 285-307 : 287-288

Hexanchus griseus (Bonnaterre, 1788)

A Bluntnose sixgill shark, Hexanchidae ( Fig. 2A ), was captured on 3 Nov. 2018 by a bottom trawler from La Cotinière. It was collected off the island of Noirmoutier (Bay of Biscay, France), at 46.7167 / 46.5600 °N, –3.4257 / –3.5833 °W, at 14:30-18:30, at 120-125 m depth on a sandy bottom. The specimen was returned alive to the sea. The adult female was estimated to be over four meters long .

The fisherman said he had not seen such a large individual for the last 15 years. Recorded by J.P. Cuillandre. Three or four small individuals of the same species were found in the same catch. One of them, a female of 650 mm TL and 809.5 g with a closed umbilical suture was examined at the Marine Station of Concarneau. These specimens were probably full term aborted individuals by the large female during the catch process. The length of the examined individual is a confirmation of the previously reported neonate size of 65-70 mm TL ( Compagno, 1984). Bycatch of juvenile bluntnose sixgill sharks by French fishing vessels is occasional in the Bay of Biscay. Quéro et al. (2011b) provided information for 174 individual historical records in the French Atlantic waters. Observations of large adult specimens are currently exceptional. The large pregnant female close to parturition reported here may document a potential birthing area for this Near Threatened species ( Cook and Compagno, 2009) with a poorly known life history.

Figures

Figure 2. – Significant French ichthyo- logical records for 2018. A: Hexanchus griseus,> 4 m TL, 3 Nov. 2018 (white arrow = full term aborted individual ~65 cm TL); B: Squatina squatina, 126 cm TL, 10 Mar. 2018; C: Gymnu- ra altavela, ~30 cm TL, 23 Apr. 2018, (photograph: Don Jacques Pompa); D: Acipenser sturio, 115 cm TL, 4 Jun. 2018 (photograph: Pierre Nicolas), E: Acipenser gueldenstaedtii, ~60 cm TL, 9 Jun. 2018 (beached); F: Dalo- phis imberbis, ~40 cm TL, 3 Mar. 2018 (beached).