The diet of deep-water sharks

Martin, Ulrich; Mallefet, Jérôme

doi:10.1016/j.dsr.2022.103898

Cited by 6 publications

(6 citation statements)

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“…The predation among sharks remains and intriguing enigma in the scientific community (Corteś, 1999), and further studies are needed to elucidate these predation preferences (Lotze et al, 2006;Navarro et al, 2014). Finally, the large abundance of crustaceans and cephalopods in the diet of kitefin shark reflects the relative abundance of these preys in the deep-sea consistently with the optimal foraging theory (Pyke, 1984;Kabasakal and Kabasakal, 2002;Mulas et al, 2021) as reported in other shark species and in general for fish species (Valls et al, 2011;Sinopoli et al, 2012;Navarro et al, 2014;Martin and Mallefet, 2022). The gut of kitefin sharks investigated in the present study contained a rich endoparasitic helminthofauna.…”

Section: B a Figurementioning

confidence: 82%

“…licha is a piscivorous predator species, specialised in hunting fast fish preys, either strictly demersal and bentho-pelagic (Navarro et al, 2014). The hepatosomatic index of this species shows significant higher values in smaller individuals, which could be related to a remarkable swimming capacity associated to the predatory behaviour (Martin and Mallefet, 2022). As observed in other deep-sea shark species, the slight increase in the gonadosomatic index reported in the present study for males could be related to their deeper bathymetric distribution than the females (Moura et al, 2014) and the lower values observed in mature females could be related to the vitellogenesis (Clarke et al, 2001).…”

Section: B a Figurementioning

confidence: 99%

“…In the Mediterranean Sea, the kitefin shark is the second most important top predator inhabiting the deep-sea after the six-gill shark Hexanchus griseus (Serena, 2005). This species is mostly reported from the Western Basin, but it is also present in the Eastern basin (Bradai et al, 2012;Guallart and Walls, 2016;Martin and Mallefet, 2022). It is frequently included in the bycatch of deep-sea fisheries, mainly bottom trawling targeting the shrimps Aristeus antennatus and Aristaeomorpha foliacea (Serena, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea

Bottaro,

Sinopoli,

Bertocci

et al. 2023

Front. Mar. Sci.

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Due to their late maturation, extreme longevity, low fecundity and slow growth rates, deep-sea Chondrichthyes are extremely vulnerable to human impacts. Moreover, assessing the impact of deep-sea fisheries is difficult, as many species (including sharks) are part of the bycatch and are often discarded at sea, and/or landed under generic commercial-species codes. The lack of this information on fishery data sets and the limited availability of species-specific life history data make challenging the management of deep-sea Chondrichthyes. The kitefin shark Dalatias licha is a cosmopolitan elasmobranch, mainly found on continental and insular shelf-breaks and slopes in warm-temperate and tropical waters. This species is a common by-catch of the deep-sea trawling, considered as “Endangered” by the IUCN Red List for all European waters, Mediterranean Sea included. Here we present the results of a study based on a total of 78 specimens of kitefin shark collected over 3 years in the Ligurian Sea (NW Mediterranean) as by-catch from deep-water fisheries. Total length ranged from 380 to 1164 mm, and individual weight ranged from 198 to 8000 g. Immature and mature individuals showed a sex ratio dominated by males. Adult males were observed throughout the year, while mature females were observed only in spring-summer. These data lead to hypothesise a spatial segregation between genders. The kitefin shark diet was dominated by bony fish (mainly Macrouridae) and other small sharks (e.g., Galeus melastomus and Etmopterus spinax), but their gut included plastic items and parasites. Data reported here underline the rarity, complex ecology and the threat for this shark species and support the urgency of promoting initiatives for their monitoring and conservation.

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Section: B a Figurementioning

confidence: 82%

Section: B a Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea

Bottaro,

Sinopoli,

Bertocci

et al. 2023

Front. Mar. Sci.

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“…Etmopterus lucifer has almost four times more ampullae of Lorenzini compared to other species studied by Kajiura et al ( 2010 ). The high number of electroreceptors could facilitate the detection of fast and agile prey, especially in the open water column (Kajiura et al, 2010 ) as prey items of this opportunistic feeder also encompasses squids and myctophid fishes (Martin & Mallefet, 2022 ). Further, pores and ducts associated with transporting electric signals to synapses with a larger diameter, which are often found in deep‐sea sharks, reduce the electrical impedance along the length of the duct.…”

Section: Discussionmentioning

confidence: 99%

Head anatomy of a lantern shark wet‐collection specimen (Chondrichthyes: Etmopteridae)

2023

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In this study, we apply a two‐step (untreated and soft tissue stained) diffusible iodine‐based contrast‐enhanced micro‐computed tomography array to a wet‐collection Lantern Shark specimen of Etmopterus lucifer . The focus of our scanning approach is the head anatomy. The unstained CT data allow the imaging of mineralized (skeletal) tissue, while results for soft tissue were achieved after staining for 120 h in a 1% ethanolic iodine solution. Three‐dimensional visualization after the segmentation of hard as well as soft tissue reveals new details of tissue organization and allows us to draw conclusions on the significance of organs in their function. Outstanding are the ampullae of Lorenzini for electroreception, which appear as the dominant sense along with the olfactory system. Corresponding brain areas of these sensory organs are significantly enlarged as well and likely reflect adaptations to the lantern sharks' deep‐sea habitat. While electroreception supports the capture of living prey, the enlarged olfactory system can guide the scavenging of these opportunistic feeders. Compared to other approaches based on the manual dissection of similar species, CT scanning is superior in some but not all aspects. For example, fenestrae of the cranial nerves within the chondrocranium cannot be identified reflecting the limitations of the method, however, CT scanning is less invasive, and the staining is mostly reversible and can be rinsed out.

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“…To date, most of the ecology (e.g., lifespan, litter size, reproduction strategy) of this species remains unknown. Even if the diet of this midwater ovoviviparous shark remains enigmatic, Squaliolus laticaudus, a phylogenetically closed species mainly feeds on small midwater fishes, cephalopods, and crustaceans [40]. This work aims to investigate the photophore's and associated structures' morphogenesis, with a specific emphasis on the apparition of a homologous encephalopsin, during the embryonic development of a dalatiid species, Squaliolus aliae (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Photophore Morphogenesis and Extraocular Encephalopsin Expression during the Embryogenesis of Smalleye Pygmy Shark (Squaliolus aliae)

Duchatelet

Mallefet

2022

Diversity

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Bioluminescence is a common phenomenon in marine organisms, especially in deep water where faint blue light remains. Among elasmobranchs, three families display the ability to emit light, the Etmopteridae, the Dalatiidae, and the Somniosidae. Luminous sharks have thousands of minute light organs, called photophores, that are mainly present ventrally and produce light. The main function of shark luminescence is counterillumination to camouflage the shark silhouette by mimicking the residual ambient light and avoiding being spotted by predators underneath. To perform counterillumination efficiently, luminescence needs to be finely adjusted. A new type of control was recently demonstrated via extraocular photoreception at the level of the light organ. An encephalopsin (i.e., opsin 3) was shown to be expressed in the vicinity of the photophore of an Etmopteridae species, Etmopterus spinax. This opsin was also demonstrated to be expressed concomitantly with the photophore development (i.e., when photophores become able to produce light) during E. spinax embryogenesis. To understand the photophore morphogenesis of different shark families, we analyzed the smalleye pygmy shark, Squaliolus aliae, with a photophore formation which represents the first report on the Dalatiidae family. Since Dalatiidae and Etmopteridae are phylogenetically closely related, the photophore morphogenesis was compared with an Etmopteridae representative, Etmopterus spinax. The results also reveal that Squaliolus aliae shares similar encephalopsin expression pattern as in Etmopterus spinax, which further supports evolutionary conservation of photophore morphogenesis as well as its own encephalopsin-based light perception across the two luminous shark families.

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The diet of deep-water sharks

Cited by 6 publications

References 177 publications

Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea

Jaws from the deep: biological and ecological insights on the kitefin shark Dalatias licha from the Mediterranean Sea

Head anatomy of a lantern shark wet‐collection specimen (Chondrichthyes: Etmopteridae)

Photophore Morphogenesis and Extraocular Encephalopsin Expression during the Embryogenesis of Smalleye Pygmy Shark (Squaliolus aliae)

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