Captive Birth of Tiger Shark (<i>Galeocerdo cuvier</i>) Reveals a Shift in Respiratory Mode during Parturition

Tomita, Taketeru; Touma, Hideyuki; Murakumo, Kiyomi; Yanagisawa, Makio; Yano, Nagisa; Oka, Shin-ichiro; Miyamoto, Kazuaki; Hanahara, Nozomi; Sato, Keiichi

doi:10.1643/ci-17-683

Cited by 6 publications

(7 citation statements)

References 5 publications

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“…Thus, it is not an observation under natural conditions. To the best of our knowledge, the observation of embryonic behavior in natural conditions has been reported for three elasmobranch species, including Mobula alfredi , Squalus japonica , and Galeocerdo cuvier (Tomita et al, ). In these species, embryonic behavior was restricted to the respiratory mouth movement (i.e., buccal pumping), not embryonic locomotion.…”

Section: Discussionmentioning

confidence: 99%

“…Recent advances in ultrasound technology, mainly the increased portability of instruments, have provided a novel opportunity to observe pregnant females of live‐bearing elasmobranchs (sharks, skates, and rays), which has revealed the poorly known embryonic behavior of nonmammalian vertebrates (Tomita, Cotton, & Toda, ; Tomita, Toda, Uchida, & Nakaya, ; Tomita et al, ). However, ultrasound devices cannot be used underwater, and specimens should be kept near the surface of the water during observation.…”

Section: Introductionmentioning

confidence: 99%

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Locomotion is not a privilege after birth: Ultrasound images of viviparous shark embryos swimming from one uterus to the other

et al. 2018

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Underwater ultrasound, a new tool for observing the internal body parts of aquatic animals by scuba divers, allowed us long‐term and frequent observations of the embryos of captive aquatic vertebrates. New ultrasound data of captive tawny nurse sharks (Nebrius ferrugineus) revealed that their embryos frequently migrate between the right and left uteri during gestation. This report is the first reliable evidence of active embryonic locomotion in live‐bearing vertebrates and is contradictory to the concept of “sedentary embryo” which has mainly arisen from studies of mammals. The tawny nurse shark is unique among orectolobiform sharks, in which the embryo develops by feeding on sibling eggs in utero. Thus, we hypothesized that swimming aids in an efficient search and capture of these eggs in the uterine environment.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Locomotion is not a privilege after birth: Ultrasound images of viviparous shark embryos swimming from one uterus to the other

et al. 2018

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“…Nurse Shark can buccal pump and possess spiracles. Tiger Shark buccal pump at birth and later switch to ram ventilation (Tomita et al 2018). Both Morgan and Burgess (2007) and Lotti et al (2011) speculated that Tiger Shark and Bull Shark may both be able to buccal pump when necessary.…”

Section: Hook Comparisonmentioning

confidence: 99%

Less Soak Time Saves Those upon the Line: Capture Times and Hooking Mortality of Sharks Caught on Bottom Longlines

Gulak

Carlson

2021

N American J Fish Manag

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The National Marine Fisheries Service is mandated by the Magnuson–Stevens Fishery Conservation and Management Act to implement effective annual catch limits and accountability measures to prevent overfishing. These requirements compel further research into alternative fishing practices that could reduce mortality of sharks (class Chondrichthyes) and allow fishers to release unwanted sharks to the water alive, while still effectively catching targeted species. We used hook timers and temperature–depth recorders aboard contracted vessels and participants in the National Marine Fisheries Service’s Shark Research Fishery to collect hooking time and time‐on‐the‐line data for 10 species of sharks that were commonly encountered in the fishery. A subset of standardized fishing sets compared the most popular circle hook and J‐hook models. Over 60% of sharks were hooked within 4 h of hook soak time. The fastest to bite the hook was the Atlantic Sharpnose Shark Rhizoprionodon terraenovae and the slowest was the Dusky Shark Carcharhinus obscurus. Shark resilience to time on the longline varied among species, with Sandbar Shark C. plumbeus exhibiting the most resilience and Atlantic Sharpnose Shark the least. Shorter set soak times, approximately 2 h, would still maximize catch, while minimizing at‐vessel mortality. The most frequently used circle hook model did not significantly reduce at‐vessel mortality over large J‐style hooks. The recent circle hook requirement will have little effect for fishers that previously used 12/0 J‐hooks, but it may be beneficial by preventing the use of smaller J‐hooks that are more likely to cause at‐vessel mortality.

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“…Some shark species are obligate ram ventilators, but most are active ventilators, especially at zero or low swimming speeds ( Barker et al. 2011 ; Ferry-Graham 1999 ; Roberts 1975 ; Tomita et al. 2018 ; Wegner et al.…”

Section: Introductionmentioning

confidence: 99%

“…2011 ; Dolce and Wilga 2013 ; Graham et al. 1990 ; Roberts 1975 ; Thomson and Simanek 1977 ; Tomita et al. 2018 ; Wegner et al.…”

Section: Introductionunclassified

Dermal Denticle Diversity in Sharks: Novel Patterns on the Interbranchial Skin

Gabler-Smith

Wainwright

Wong

et al. 2021

Integrative Organismal Biology

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Shark skin is covered in dermal denticles – tooth-like structures consisting of enameloid, dentine, and a central pulp cavity. Previous studies have demonstrated differences in denticle morphology both among species and across different body regions within a species, including one report of extreme morphological variation within a 1 cm distance on the skin covering the branchial pouches, a region termed “interbranchial skin”. We used gel-based profilometry, histology, and scanning electron microscopy to quantify differences in denticle morphology and surface topography of interbranchial skin denticles among 13 species of sharks to better understand the surface structure of this region. We show that 1) interbranchial skin denticles differ across shark species, and 2) denticles on the leading edge of the skin covering each gill pouch have different morphology and surface topography compared to denticles on the trailing edge. Across all species studied, there were significant differences in denticle length (P = 0.01) and width (P = 0.002), with shorter and wider leading edge denticles compared to trailing edge denticles. Surface skew was also higher in leading edge denticles (P = 0.009), though most values were still negative, indicating more valleys than peaks. Overall, leading edge denticles were smoother-edged than trailing edge denticles in all of the species studied. These data suggest two hypotheses: 1) smoother-edged leading edge denticles protect the previous gill flap from abrasion during respiration, and 2) ridged denticle morphology at the trailing edge might alter water turbulence exiting branchial pouches after passing over the gills. Future studies will focus on determining the relationship between denticle morphology and water flow by visualizing fluid motion over interbranchial denticles during in vivo respiration.

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Captive Birth of Tiger Shark (Galeocerdo cuvier) Reveals a Shift in Respiratory Mode during Parturition

Cited by 6 publications

References 5 publications

Locomotion is not a privilege after birth: Ultrasound images of viviparous shark embryos swimming from one uterus to the other

Locomotion is not a privilege after birth: Ultrasound images of viviparous shark embryos swimming from one uterus to the other

Less Soak Time Saves Those upon the Line: Capture Times and Hooking Mortality of Sharks Caught on Bottom Longlines

Dermal Denticle Diversity in Sharks: Novel Patterns on the Interbranchial Skin

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