Publications by authors named "Shoou-Jeng Joung"

A new species of Malakichthys is described based on six specimens collected from deepwaters off southwestern Taiwan, northwestern Pacific Ocean. The new species, M. formosus sp.

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Mercury (Hg) is known to be maternally transferred during embryonic development in sharks; however, Hg concentrations in embryos of filter feeding shark species have not previously been reported. This study measured the total Hg (THg) concentration in muscle tissue of 27 embryos taken from a pregnant whale shark (Rhincodon typus) landed in Taiwan in 1995 and the mean THg concentration compared to the mean muscle THg concentration in embryos from other shark species. The mean (± standard deviation) THg concentration in whale shark embryos was 0.

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A new species of Okamejei is described based on two adult males collected from deep waters in the South China Sea. The new species, Okamejei picta sp. nov.

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Article Synopsis
  • The longnose houndshark, Iago garricki, was initially described using five specimens found in Vanuatu and has now been redetermined based on additional specimens from Dongsha Atoll in the South China Sea.
  • These sharks have distinct characteristics such as a larger eye length compared to gill slit height and specific measurements of head and body proportions.
  • The recent finds extend the known distribution of this species, marking the northernmost occurrence of the longnose houndshark.
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The milk-eye catshark Apristurus nakayai Iglésias, 2012 was known from three specimens in the southwestern Pacific Ocean. Six specimens were recently collected from the South China Sea. It belongs to the brunneus group, and superficially resembles A.

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In the Pacific Ocean, the rare Bigeye Sand Tiger shark Odontaspis noronhai has only been recorded twice, once from its central and once from its eastern part. Here we report the first record of this species from the northwestern Pacific. This specimen measuring 312 cm total length (TL) was captured off northeastern Taiwan (2525N, 12410E) from a depth of 100 m (in waters over 2100 m deep) in mid-December 2019, and was retrieved on 27 December 2019 when landed in port.

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Article Synopsis
  • The megamouth shark is a rare species with limited biological and fishery data, based on 261 landing/stranding records, including various sex distributions.
  • Their depth distribution ranges from 0 to 1203 meters, with immature sharks mostly found in shallower waters (<200 m), while mature sharks can dive deeper and migrate to higher latitudes.
  • The majority are concentrated in the western North Pacific, and potential nursery areas are identified in the Indian and Atlantic Oceans, with females showing a tendency to move to higher latitudes than males.
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  • The study evaluated the vulnerability of 11 pelagic shark species affected by Taiwanese longline fisheries in the western North Pacific, using an ecological risk assessment (ERA).
  • The assessment combined factors like population growth rates and fishing impacts, categorizing species into risk groups, with the scalloped hammerhead identified as the most at-risk species.
  • Recommendations include strict management for the highest-risk species, catch quotas for moderately at-risk species, and ongoing monitoring for those at lower risk.
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A new species of sleeper shark is described based on a 134.0 cm total length pregnant female collected from off Hualien, eastern Taiwan. The species belongs to a small species group (subgenus ) and can be distinguished from its congeners in having a smaller second dorsal fin, smaller eyes, more rows of teeth in the upper jaw and fewer in the lower jaw, and a different body proportion.

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Focusing on 27 rare filter-feeding megamouth sharks (Megachasma pelagios) captured as a by-catch of drift gillnet fishery in the Pacific Ocean to the east of Taiwan, this study analyzes the concentrations of 24 elements in their muscle, discusses the bioaccumulation of each element and the correlation between different elements, and assesses the potential health risks of consuming megamouth shark muscle. Among the 24 elements, mean concentrations of Ga, Ag, Li, Bi, Hg, Co, and Cd were relatively low ranging from 10 to 10 mg/kg, those of Pb, Ba, Mn, Ni, As, Cr, B, Sr, Cu, and Zn ranged from 10-10 mg/kg, and those of Fe, Ca, Al, K, Mg, Ti, and Na were relatively high ranging from 10 to 10 mg/kg. The toxic element content index was most significantly correlated with the concentration of Cu.

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Article Synopsis
  • The megamouth shark, a newly identified species since 1983, has been rarely observed, complicating our understanding of its movement and population dynamics.
  • Researchers analyzed tissue samples from 27 megamouth sharks in Taiwan and other regions to study genetic diversity and found no genetic structure, indicating a potentially interbreeding population.
  • Results suggest that the Kuroshio region may serve as a migratory route for these sharks, and future research should focus on more samples and satellite tracking to enhance knowledge of their global migration.
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Five new records of elasmobranchs collected from eastern Taiwan fish markets, Da-xi and Cheng-gong, are presented. Samples were caught by deepsea longliners and bottom trawlers which operate in northeastern waters off Taiwan between 2004 and 2012. These five new species records include the smalltooth sandtiger, Odontaspis ferox (Risso, 1810) (Lamniformes: Odontaspididae), salamander shark, Parmaturus pilosus Garman, 1906 (Carcharhiniformes: Scyliorhinidae), leadhued skate Notoraja tobitukai (Hiyama, 1940) (Rajiformes: Arhynchobatidae), giant skate Dipturus gigas (Ishiyama, 1958) (Rajiformes: Rajidae), and the pelagic stingray Pteroplatytrygon violacea (Bonaparte, 1832) (Myliobatiformes: Dasyatidae), Diagnostic characteristics for each species are given and a key to the genera Parmaturus and Dipturus from Taiwan is presented.

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