New record and morphometry of the bluntnose sixgill shark Hexanchus griseus (Chondrichthyes: Hexanchidae) in Baja California Sur, Mexico

Abstract

ABSTRACT. We report the first record and morphometry of a complete juvenile Hexanchus griseus female shark, caught in Punta Lobos, Baja California Sur, Mexico. The oceanographic conditions of the area, where the specimen was caught, coincide with the habitat previously described for this shark species, with low temperature, stable salinity and high hydrostatic pressure. There is an overall lack of information about H. griseus in Mexico, with only eight records of its presence in the Mexican Pacific. Moreover, none of these previous records provided detailed information on the morphometry of a whole bluntnose sixgill shark. Here, we present the morphometric measures of a complete individual caught in shallow waters. We expect this information to be useful for future comparisons of specimens caught in other coastal regions.

First in situ record of the deep-sea shark Hexanchus griseus (Chondrichthyes: Hexanchidae) off Rapa Nui (Easter Island, Chile), and management implications

“…Through this method, the estimated TL was 146 cm with an FL of 119 cm (Fig. 3), confirming the TL obtained by applying the conversion factor suggested by Becerrill- García et al (2017). Since it has been proposed that males of this species mature at 309 cm (Crow et al 1996), the specimen was an immature individual.…”

“…It also occurs on seamounts and mid-ocean ridges and is often associated with high biological productivity and upwelling areas (Ebert et al 2013). Juveniles can make incursions over the continental shelf, as was reported recently by Becerril-García et al (2017), who described the incidental catch of a juvenile female by coastal fishermen of Punta Lobos, Baja California Sur, Mexico (northeastern Pacific). Hexanchus griseus is infrequently reported as either targeted or incidental catch from industrial and artisanal demersal trawl, longline, handline, traps, and gillnet fisheries (Finucci et al 2020 and references therein).…”

First record of a neonate bluntnose sixgill shark (Hexanchus griseus) from Baja California Sur, Mexico

“…Whilst not listed as data deficient by the IUCN (Finucci et al., 2020 ), little is known about the biology and ecology of H. griseus across much of its range. In some cases, knowledge of the species in each region comes from just a handful of studies focused on a few individuals (Becerril‐García et al., 2017 ; Lipej et al., 2022 ). In the Mexican Pacific, for example, only 8 records of the species exist in the literature (Becerril‐García et al., 2017 ).…”

“…In some cases, knowledge of the species in each region comes from just a handful of studies focused on a few individuals (Becerril‐García et al., 2017 ; Lipej et al., 2022 ). In the Mexican Pacific, for example, only 8 records of the species exist in the literature (Becerril‐García et al., 2017 ). Without further study, it is impossible to discern the status of H. griseus populations, the extent to which they may be threatened by intense fishing pressure and to provide the necessary management and protection measures to prevent population decline (Vella & Vella, 2017 ).…”

NEW RECORD OF THE BLUNTNOSE SIXGILL SHARK, Hexanchus griseus (CHONDRICHTHYES, HEXANCHIDAE) IN THE SOUTH WEST ATLANTIC OCEAN

“…Morphometry comparison between females of Hexanchus griseus Becerril-García et al (2017)Coscarella et al (1997)…”