The sharpnose sevengill shark (Heptranchias perlo) is a rare and poorly understood deep‐sea species, with only a few records in the Adriatic Sea over the last two centuries and a significant gap in ...sightings.
Throughout 2023, three new records are documented in the southernmost Adriatic Sea, found at depths ranging from 391 to 452 m off Vlorë.
This study marks the first comprehensive health examination of a deep‐sea shark, investigating potential trauma and injuries resulting from trawling. It encompasses pathological and histopathological examinations, supplemented by magnetic resonance imaging (MRI).
The research highlights alarming post‐capture mortality rates in this data deficient species, discusses further conservation implications, and proposes protective measures for the species.
Beyond addressing critical knowledge gaps, this study advocates for collaborative efforts with local fishermen to establish long‐term monitoring and obtain data on the frequency and abundance of elusive species.
The dermal denticles are among the unique morphological adaptations of sharks, which have been acquired throughout their long evolutionary process of more than 400 million years. Species‐specific ...morphological characteristics of these structures has been applied specially as tools for functional and taxonomic (family‐level) studies. Nevertheless, few studies have explored the diversity of denticle structure in different around the body and oral cavity. In the present study, we described the morphological differences observed in skin and oral cavity of sharpnose sevengill shark Heptranchias perlo, using scanning electron microscopy. Our findings demonstrate substantial variation in morphological structure of the denticles of the body and oral cavity. Overall, the dermal denticles observed across body surface were overlapped, tricuspid, with the central cuspid being more pronounced, pointed, and triangular in shape compared with lateral ones. Unlike, the denticles on the tip of the nose had a smooth crown, with rounded edges, being compact, and overlapped. The oral denticles were found in the ventral and dorsal region of the oral cavity. They also were tricuspid, but with differences in arrangement and ridges. These results suggest a strict functional relationship with the morphological characteristics observed. Such morphological diversity body‐region‐dependent highlights the need for comparative studies that include oral denticles, since this structure has an important functional role in sharks and can be found in fossil and recent records.
Morphological diversity body‐region‐dependent of the dermal and oral denticles of sharpnose sevengill shark, Heptranchias perlo.
In March 2018, an immature female sharpnose sevengill shark Heptranchias perlo was caught by a commercial bottom trawler in the Ibiza Channel. This represents the first substantiated record of the ...species around the Balearic Islands (GSA05) and the second record from off the Spanish Levantine coasts. This paper includes a review of the records of H. perlo in the Mediterranean as an aid to future conservation assessments.
Cartilaginous fish are commonly recognized as key species in marine ecosystems for their fundamental ecological role as top predators. Nevertheless, effective management plans for cartilaginous fish ...are still missing, due to the lack of knowledge on their abundance, distribution or even life-history. In this regard, this paper aims at providing new information on the life-history traits, such as age, maturity, reproductive period, in addition to diet characteristics of eleven rare cartilaginous fish inhabiting the Central-Western Mediterranean Sea belonging to the orders Chimaeriformes (Chimaera monstrosa), Hexanchiformes (Heptranchias perlo and Hexanchus griseus), Myliobatiformes (Aetomylaeus bovinus and Myliobatis aquila), Rajiformes (Dipturus nidarosiensis and Leucoraja circularis), Squaliformes (Centrophorus uyato, Dalatias licha and Oxynotus centrina) and Torpediniformes (Tetronarce nobiliana), useful for their assessment and for future management actions. Particularly, the present paper provides for the first time the age estimation of D. nidarosienis and L. circularis which were both found capable of becoming older than ten years. In addition, the present study updates the sizes of first maturity of C. uyato and D. licha, which appeared to be capable of reproducing earlier than what was previously hypothesized, representing very valuable information for a better understanding of these rare species populations status and, eventually, their conservation. On the basis of the stomach content analysis, it was possible to identify five different predator groups.
Summary
Elasmobranchs are commonly landed without fins and heads; however, the knowledge of total length is necessary for fishery management. We provide useful equations to extrapolate partial from ...elasmobranch carcasses lengths, to total lengths. Length‐Length Relationships (LLR) are described for 16 commercial elasmobranch species all included in the IUCN Red List: Hexanchus nakamurai, Heptranchias perlo, Squalus cubensis, Squatina dumeril, Scyliorhinus boa, Mustelus minicanis, M. higmani, M. norrisi, Carcharhinus acronotus, C. falciformis, C. limbatus, Galeocerdo cuvier, Rhizoprionodon lalandii, R. porosus, Sphyrna lewini and Pseudobatos percellens. This study provide new LLR equations and rsepresent an improvement in the knowledge of these species.
Quantifying the feeding ecology of marine predators is essential for understanding their trophic interactions and their potential regulatory effects in marine ecosystems. I quantified the feeding ...ecology of 2 related predators that overlap only in part in spatial distribution: the coastal broadnoseNotorynchus cepedianusand the deepwater sharpnoseHeptranchias perlosevengill sharks. I found the following: These 2 shark species have different diet specialisation patterns, but show similarities in their prey handling mode.N. cepedianushas a generalised diet, whereasH. perloshows high specialisation and lower prey diversity. For both shark species, small, medium and large individuals use different strategies for handling different prey groups.H. perlopreys largely on deepwater teleosts, mainlyLepidorhynchus denticulatus, with larger individuals (901 to 1365 mm total length, TL) also consuming high proportions of large predatory teleosts of the families Gempylidae and Trichiuridae.N. cepedianushas a diverse diet. Small individuals (≤900 mm TL) prey largely on teleosts and secondarily on chondrichthyans. Medium individuals (901 to 1520 mm TL) prey primarily on chondrichthyans and secondarily on teleosts. Chondrichthyans (mainlyMustelus antarcticus) are also the main prey of largeN. cepedianus(>1700 mm TL), but this group also shows a greater preference (than small and medium individuals) for fur seals. Despite the overall differences in dietary composition and the minimal overlap in spatial distribution, the 2 shark species consume prey that migrate from deep to coastal waters (ommastrephid squid and gempylid fish).
Three species of neonate and juvenile sharks (
Heptranchias perlo
,
Squatina aculeata
,
Etmopterus spinax
) were captured as by-catch from a commercial trawl fishing from depths between 360 and 430 m ...in the North-eastern Mediterranean Sea. Two neonates of
H. perlo
, five neonates of
E. spinax
and one juvenile of
S. aculeata
were for the first time identified in the above region.
Isopods are micropredators of deep-water sharks; however, their associations are poorly described in the scientific literature. We present the association of three isopod genera
Aega
sp.,
Aegaphales
...sp., and
Cirolana
sp. with two species of deep-sea shark, the Cuban dogfish (
Squalus cubensis
) and the sharpnose sevengill (
Heptranchias perlo
). Although limited conclusions can be drawn from this observation, it provides a novel association of micropredatory isopods with two poorly studied species of deep-water shark.
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