Species identification of sharks under catch or trade regulations is important for law enforcement and species conservation. Rapid detection of Convention on the International Trade in Endangered ...Species (CITES)‐listed species is needed for on‐site screening.
Species‐specific primers were designed to target three mitochondrial genes (ND2, COI, and CytB) in both the simplex and multiplex loop‐mediated isothermal amplification (LAMP) assay for the pelagic thresher shark (Alopias pelagicus), the bigeye thresher shark (Alopias superciliosus), and the scalloped hammerhead shark (Sphyrna lewini), respectively. Another primer set designed to target S. lewini was used for detection‐limit testing of the LAMP assay.
The refined direct multiplex LAMP was used to detect the three CITES‐listed shark species and omitted the lengthy DNA extraction process. A homogenizer was used to release the DNA from the shark tissues, and a simplex or multiplex LAMP reaction was conducted for 30 min in an incubator at 65°C using species‐specific primer sets.
Positive LAMP reactions showed a colour change from pink to yellow, whereas negative reactions showed no colour change. Multiplex LAMP assays were performed using 84 samples, which successfully identified the target and non‐target species and provided a fast (<1 h), simple, and reliable method to distinguish three CITES‐listed shark species from the other non‐target species, for either fresh or dry fin products.
Results of this study and the method developed will play a critical role in assisting fishery agencies and customs officials in identifying the illegal catch and trade of CITES‐listed shark species.
Small-bodied sharks are recognized as mesopredators on different communities in a large variety of habitats, thus linking the trophic levels in the marine ecosystem. Dietary analysis on these species ...can provide insight into the trophic relationships in food webs. Our study analyzed the diet composition of
Galeus sauteri
, an abundant small shark inhabiting neritic shelf waters at depths between 60 and 200 m. For this purpose, a stomach content analysis was realized in 678 specimens collected by bottom trawlers off northeastern Taiwan from September 2018 to August 2019. The two most commonly consumed preys were teleosts (prey-specific index of relative importance, %PSIRI = 51.94) and crustaceans (%PSIRI = 30.08).The results for the Levin’s index (Ba = 0.06) and graphical analysis based on the Costello method revealed a high degree of specialization on lanternfishes and other teleosts. The mean trophic position was 4.29. Feeding habits differed significantly in relation to maturity condition and between seasons. Our result showed that
G. sauteri
is a primary piscivorous shark that preys mainly on lanternfishes and other teleosts, and feeds opportunistically on crustaceans and cephalopods.
The reproductive biology of a commercially important sparid, the goldlined seabream
Rhabdosargus sarba
, was determined from examination of 802 specimens (443 females, 232 males, 68 fish of ...undifferentiated sex, and 59 bisexual fish) collected by fisheries operating in the central waters of the Taiwan Strait (henceforth “central Taiwan Strait”) from January to December 2016. Previous studies undertaken in other parts of the world have yielded conflicting information on the reproductive biology of this species. Based on macroscopic appearance, the gonadosomatic index, and histological examination of the gonad tissues, the spawning season of this species in the central Taiwan Strait was determined to be from December to March.
R. sarba
is an asynchronous spawner, with a mean estimated fecundity of 825,078 ± 431,672 eggs. The sex ratio, 0.66, was significantly different from 0.5, and females predominated in most size classes and monthly samples. Size at 50% maturity was estimated to be 23.7 and 20.9 cm fork length for females and males, respectively. Ovotestes were identified in both young and adult individuals, which suggests that
R. sarba
is a rudimentary hermaphrodite in the central Taiwan Strait. This finding is similar to that for conspecifics reported from Australia, but differs from those reported for other geographical regions. Monthly variation in the condition factor and in the hepatosomatic index indicated that the energy reserves of the muscles and liver may be closely linked to the spawning activity of this species.
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. nov., exhibits ...distinct morphological characters, primarily characterized by the absence of chin spines, distinguishing it from other congeners with the exception of M. levis and M. mochizuki. It differs from the two species by having more lateral-line scales, a shorter distance between the snout and dorsal-fin origin, a shallower head, fewer scale rows below the lateral line, and the structure of the first anal-fin pterygiophore. Eight species are now recognized in Malakichthys.
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. platyrhynchus Tanaka, 1909. Apristurus nakayai differs from A. platyrhynchus by the following characters: iris shiny white when fresh; body brownish black to black; second dorsal-fin insertion above or slightly in front of the anal-fin insertion; denticles absent inside mouth; and maturing at about 400 mm TL in both sexes. The occurrence of Apristurus nakayai from the South China Sea represents the first record in the northern Hemisphere, and a substantial distributional range extension (ca. 4665 km).
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 0.0762 ± 0.0163 µg/g dry weight (0.0224 ± 0.0054 µg/g wet weight). There was no relationship between muscle THg concentration and body length and no significant difference in THg concentration between male and female embryos (p > 0.05). Whale shark embryos have the lowest reported muscle THg concentrations compared to literature values for muscle THg concentrations for embryos from other shark species.
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., is readily distinguished from most other ...congeners in having densely scattered black spots on dorsal disc. Okamejei hollandi and O. mengae is quite similar to the new species by their spot patterns on dorsal disc, but the new species differs from the former by a combination of characters: a yellowish brown dorsal surface densely covered with small, circular to irregular-shaped black spots; blotches on dorsal disc indistinct; posterior ocellus absent; ventral disc white; disc length 45.0-47.7% TL; distance between cloaca to caudal-fin tip 53.6-55.1% TL; trunk centra 31; total basal radials 73-76, morphology of clasper terminal skeleton, and lacking component funnel at the clasper end.
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 ...Rhinoscymnus) 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. Moreover, the specimen had 33 embryos, which is substantially more than the two other small species in the subgenus. Information on embryo biology are also provided.
The longnose houndshark, Iago garricki Fourmanoir & Rivaton 1979, was described based on five specimens collected from Vanuatu. Five additional specimens were recently collected from the waters off ...Dongsha Atoll, South China Sea. A redescription of this species is provided based on the holotype, non-types collected near the type locality and off Dongsha Atoll. The species is characterized by eye length larger than gill slit height; first dorsal-fin origin not reaching a vertical line through pectoral-fin base; head length 20.2-22.2% TL; preoral length 7.2-8.3% TL; upper labial furrow 2.2-3.4% TL; lateral teeth with 1-3 small cusplets on lateral side basally; diplospondylous centra 53-61; precaudal centra 94-102; and total centra 149-157. The specimens collected from the South China Sea represent the northernmost distributional record of this species.
The reproductive characteristics of a commercially important sparid fish used in aquaculture systems, the yellowfin seabream Acanthopagrus latus, were described based on 938 specimens caught by ...various fisheries in the waters off western Taiwan from January 2016 to September 2017. Based on macroscopic appearances, gonadosomatic indices and histological examinations of the gonad tissues, the spawning season of this species was identified to be from September to December. This species is an asynchronous spawner, with an estimated mean fecundity of 2,444,787 ± 1,205,991. The sex ratio was significantly different from 0.5, and females predominated in most size classes and months. The sizes at 50% maturity were estimated to be 29.7 and 21.0 cm FL for females and males respectively. Although A. latus is believed to be a protandrous hermaphrodite in many geographical locations, the possibility of being a rudimentary hermaphrodite could not be excluded in this study. The positive correlations found between the fecundity and length, weight and age of the individuals and implications of these results with respect to their inshore migration pattern and the stock enhancement success were addressed.
