Chiloscyllium Punctatum Research Articles

PRIMARY HEPATIC NEOPLASIA IN THREE ADULT BAMBOO SHARKS (CHILOSCYLLIUM PLAGIOSUM AND CHILOSCYLLIUM PUNCTATUM) IN AN AQUARIUM POPULATION.

Neoplasia in elasmobranchs is uncommonly documented. This report describes primary hepatic neoplasia in three adult female bamboo sharks under managed care: biliary adenocarcinoma in a whitespotted bamboo shark (Case 1; Chiloscyllium plagiosum), biliary adenocarcinoma in a brownbanded bamboo shark (Case 2; Chiloscyllium punctatum), and hepatocellular carcinoma in a whitespotted bamboo shark (Case 3). Case 1 presented with extensive cutaneous papillomas and was electively euthanized. At necropsy, a 4-cm-diameter, pale-tan, firm hepatic mass was identified and diagnosed histologically as a biliary adenocarcinoma. Case 2 presented with decreasing body condition despite normal food intake. Coelomic ultrasound and exploratory surgery revealed several large masses in both hepatic lobes, and the patient was euthanized. At necropsy, nine, 1-6-cm-diameter, black to tan, firm hepatic masses were identified and diagnosed histologically as biliary adenocarcinoma with branchial intravascular neoplastic emboli. Case 3 presented for routine health examination and was euthanized for diagnostic purposes after coelomic ultrasound revealed multiple hepatic masses. At necropsy, two 1-3-cm-diameter, brown- and-black mottled, firm hepatic masses were identified and diagnosed histologically as hepatocellular carcinoma. Immunohistochemistry was performed in two of these cases and was noncontributory, likely because of a lack of cross reactivity between antibodies (antipancytokeratin) and elasmobranch tissues.

Shark and ray monitoring on the marine critical habitat in Aceh Province

Aceh is the leading province in Indonesia, where the marine protection area for juvenile sharks and rays was first established, precisely in Aceh Jaya waters. Rigaih is the fishing port located closest to Aceh Jaya waters, where the angler fish closely with the marine protected area and even intersect with the juvenile’s habitat. This study aimed to examine shark and ray catches in Aceh Jaya before and after establishing the marine protection area. We conducted landing monitoring from 2017 to 2019 (before establishing a conservation area) and monitored in 2020 when the conservation area was established. We recorded that 73% of sharks and ray caught on set gill net. The composition of sharks and rays landed at PPI Rigaih consisted of Sphyrna lewini (75%, n=1783), Chiloscyllium punctatum (8%), Neotrygon caeruleopunctata (7%, n =175), and other species (10%). This study aimed to provide scientific recommendations to support shark conservation action in Aceh Jaya Waters. We found that Aceh Jaya waters are an important area for the life stages of several threatened species, including Scalloped Hammerhead Sharks (S.lewini) and Bottlenose Wedgefish (R.australiae) that are listed in Critically Endangered and listed in Appendix II CITES. Management to support the conservation action needs to be strengthened not only limited to Marine Protected Areas but also fisheries management to reduce the incidental catch of threatened sharks and ray species. Further studies need to be conducted to delineate the habitat range of threatened shark and ray species and identify fishing behaviours that pose a risk for incidental catches of sharks and rays.

DEXMEDETOMIDINE AND MIDAZOLAM INTRAMUSCULAR SEDATION IN BROWNBANDED BAMBOO SHARKS (CHILOSCYLLIUM PUNCTATUM).

Bamboo sharks are some of the most common elasmobranch species in zoos and aquaria and are frequently sedated for medical exams, treatments, and research. This study investigated the use of an IM sedation protocol of a single dose of dexmedetomidine (0.05 mg/kg) and midazolam (2.0 mg/kg) in brownbanded bamboo sharks (Chiloscyllium punctatum). Sharks were serially monitored every 5 min for heart rate, branchial beats, righting reflex, coelomic response, cloacal response, pelvic fin reflex, response to noxious stimulus, voluntary movement, and ability to swim. This sedation dose was effective at rapidly and significantly decreasing responses to tactile and noxious stimuli with minimal respiratory depression and was quickly reversible with atipamezole (0.5 mg/kg) and flumazenil (0.05 mg/kg). Sedated sharks developed a mild metabolic acidosis evidenced by a significant increase in lactic acid (mean < 0.37 mmol/L presedation, 4.2 mmol/L after reversal) and decrease in blood pH (mean 7.464 presedation, 7.277 after reversal); however, clinical intervention was not required. This protocol should be further investigated in different elasmobranch species but is promising for providing sedation for noninvasive procedures in brownbanded bamboo sharks.

Succinate-mediated reactive oxygen species production in the anoxia-tolerant epaulette (Hemiscyllium ocellatum) and grey carpet (Chiloscyllium punctatum) sharks.

Anoxia/re-oxygenation (AR) results in elevated unchecked oxidative stress and mediates irreversible damage within the brain for most vertebrates. Succinate accumulation within mitochondria of the ischaemic brain appears to increase the production of reactive oxygen species (ROS) upon re-oxygenation. Two closely related elasmobranchs, the epaulette shark (Hemiscyllium ocellatum) and the grey carpet shark (Chiloscyllium punctatum) repeatedly experience near anoxia and re-oxygenation in their habitats and have adapted to survive AR at tropical temperatures without significant brain injuries. However, these anoxia-tolerant species display contrasting strategies to survive AR, with only H. ocellatum having the capacity to supress metabolism and H. ocellatum mitochondria the capacity to depress succinate oxidation post-AR. We measured oxygen consumption alongside ROS production mediated by elevated succinate in mitochondria of permeabilized cerebellum from both shark species. Although mitochondrial respiration remained similar for both species, the ROS production in H. ocellatum was half that of C. punctatum in phosphorylating and non-phosphorylating mitochondria. Maximum ROS production in H. ocellatum was mediated by succinate loads 10-fold higher than in C. punctatum mitochondria. The contrasting survival strategies of anoxia-tolerant sharks reveal the significance of mitigating ROS production under elevated succinate load during AR, shedding light on potential mechanisms to mitigate brain injury.

Shark and ray genome size estimation: methodological optimization for inclusive and controllable biodiversity genomics

Estimate of nuclear DNA content serves as an independent tool for validating the completeness of whole genome sequences and investigating the among-species variation of genome sizes, but for some species, the requirement of fresh cells makes this tool highly inaccessible. Here we focused on elasmobranch species (sharks and rays), and using flow cytometry or quantitative PCR (qPCR), estimated the nuclear DNA contents of brownbanded bamboo shark, white spotted bamboo shark, zebra shark, small-spotted catshark, sandbar shark, slendertail lanternshark, basking shark, megamouth shark, red stingray, and ocellate spot skate. Our results revealed their genome sizes spanning from 3.18 pg (for ocellate spot skate) to 13.34 pg (for slendertail lanternshark), reflecting the huge variation of genome sizes already documented for elasmobranchs. Our qPCR-based method ‘sQuantGenome’ enabled accurate genome size estimation without using live cells, which has been a severe limitation with elasmobranchs. These findings and our methodology are expected to contribute to better understanding of the diversity of genome sizes in elasmobranchs even including species with limited availability of fresh tissue materials. It will also help validate the completeness of already obtained or anticipated whole genome sequences.

The biological aspect of shark which landed in Karangsong’s Port, Indramayu, West Java

This study aimed to evaluate the number of catches and describe the biological aspects of sharks landing at Karangsong’s Port Indramayu, West Java. The study was conducted from July until August 2022 with the survey method. Data were taken by purposive sampling method including species, number of catches, sex, maturity level, total length, weight, fishing gear, and location. Data were analyzed to evaluate the catch while biological aspects were used to determine the condition of sharks. Analysis of biological aspects included sex ratio, length frequency, and the level of male sex maturity, as well as the length-weight relationship. A total of 407 sharks consisting of 7 species were dominated by mature sharks. Include Carcharinus dussumieri (33,2%), Carcharinus sorrah (23,8%), Carcharinus limbatus (0,2%), Sphyrna lewini (8,4%), Rhizoprionodon acutus (1,5%), Chiloscyllium punctatum (12,5%), Loxodon macrorhinus (8,4%). The results showed the frequency distribution of fish length and weight is 44 cm to 106 cm and 0,2 to 8,5 kg. Statistical test results showed that sharks had growth patterns negative allometric and Biological aspects showed an unbalanced sex ratio.Keywords: Allometric; Growth; Sex ratio; Shark

Tropical sharks feasting on and swimming through microplastics: First evidence from Malaysia

Plastic can be degraded into microplastic (<5 mm) and has been polluting worldwide marine environment and negatively impact human health. Microplastics in marine organisms are still understudied in Malaysia, let alone from a subclass Elasmobranchii. Five tropical shark species (Carcharhinus dussumieri, Carcharhinus sorrah, Chiloscyllium hasseltii, Chiloscyllium punctatum, and Scoliodon laticaudus) were examined for the presence of microplastics. 74 sharks were sampled from the local wet market and 100 % of samples contained microplastics. A total of 2211 plastic particles were found in gastrointestinal tracts (GIT) and gills, where 29.88 ± 2.34 particles per shark (mean ± SEM). Black (40.07 %) and fiber (84.44 %) microplastics were the most dominant. Extracted microplastic sizes ranged from 0.007 mm to 4.992 mm. This study suggests that microplastic uptake is gender-related for some shark species. A subsample of microplastics (10 %) was used for polymer type identification, where polyester was recorded the highest (43.95 %).

Contrast-enhanced computed tomography and cross-sectional anatomy of the trunk in the brownbanded bamboo shark (Chiloscyllium punctatum).

Computed tomography (CT) is used in veterinary medicine for the diagnosis of bones and soft tissue diseases in various species. In addition, CT has recently been used to diagnose aquatic animals, including Selachimorpha, which are difficult to diagnose out of water. However, because Selachimorpha do not have adipose tissue in the coelomic cavity, the coelomic organs cannot be fully identified using non-contrast CT (NCCT). The aim of this study is to present the anatomical features of the cadaver, NCCT, and contrast-enhanced CT (CECT) as well as the change in CT values of the coelomic organs and musculature of the brownbanded bamboo shark. NCCT scans were performed under anaesthesia in one male and one female shark. CECT was performed 30 min after iopamidol was administered intravenously. The sharks were euthanized, frozen at -20°C, and sliced in the same position in which they were scanned. Using electric band saw, 10-mm transversal sections were obtained. The anatomical structures of both males and females were identified by transversal sections, and CT images homologous to transversal sections were then selected. Sagittal and coronal CECT images were also obtained to facilitate understanding of the location and size of coelomic organs. Although bone structure and air in organs could be sufficiently discriminated on NCCT image, the coelomic organs were almost indistinguishable. On the other hand, CECT images obtained sufficient contrast to identify most coelomic organs in addition to bone and air. The results provide an atlas of a cross-sectional anatomy and CECT images, which is useful information for the medical diagnosis of coelomic organs in live Selachimorpha.

Discarded Species in Artisanal Fisheries South Sumatra, Indonesia: Case Study on Crab Gill Nets

This study identified the discard species generated by the crab gillnet for targeting the blue swimming crab Portunus pelagicus (Linnaeus 1758) in the Banyuasin estuarine of South Sumatra, Indonesia. The fishing gear yielded the discarded catch about 12% (25.68 kg) of the total catch in weight (212.68 kg). For the discarded catch, 703 individuals represented 18 species from 3 phyla (Arthropoda, Chordata, and Mollusca). The crustaceans Charybdis helleri (Milne-Edwards 1867), Clibanarius spp., Matuta planipes(Fabricius 1798), and Libinia dubia(Milne Edwards 1834) were the majority components of these discards accounted for 90% of the total discards. Results of ecological classification rare, i.e., Chiloscyllium indicum(Gmelin 1789), and occasional, i.e., Chiloscyllium punctatum(Müller &amp; Henle 1838), and Maculabatis macrura(Bleeker 1852) included in the International Union for Conservation of Nature (IUCN) red list as Vulnerable (C. indicum), Near Threatened (C. punctatum), and Endangered (M. macrura) category. Based on the IUCN status, two species of crustaceans i.e., Carcinoscorpius rotundicauda (Latreille 1802) and Tachypleus gigas (Müller 1785) listed as ‘Data Deficient’. Discarded on crab gillnet fishing in Banyuasin waters is a challenge for species that need to be conserved (shark, ray, and horseshoe crabs). Species with IUCN red list status ranging from Data Deficient to Endangered were found dead, except for horseshoe crabs. Mitigation options offered include captive breeding of horseshoe crabs, the release of protected species when caught, and fishing gear modification. These findings can help design suitable mitigations for discarding crab gill nets.

Cranial morphology of the orectolobiform shark, Chiloscyllium punctatum Müller &amp;amp; Henle, 1838

Elasmobranchs, comprising sharks, skates, and rays, have a long evolutionary history extending back into the Palaeozoic. They are characterized by various unique traits including a predominantly cartilaginous skeleton, superficial prismatic phosphatic layer, and permanent tooth replacement. Moreover, they exhibit a more or less marked sexual dimorphism. Especially the morphology of the chondrocranium and the elements of the whole cranial region of extant and extinct chondrichthyans can provide valuable information about corresponding functions, e.g. the feeding apparatus might reflect the diet of the animals. However, studies on sexual dimorphisms are lacking in orectolobiform sharks, therefore, little is known about possible sexual dimorphic characters in the cranial region in this group. For this reason, we present in this study a comprehensive morphological description of the cranial region of the brownbanded bamboo shark Chiloscyllium punctatum Müller & Henle, 1838, with a special focus on its sexual dimorphic characters. Our results reveal clear morphological differences in both sexes of the examined C. punctatum specimens, particularly in the chondrocranium and the mandibular arch. The female specimen shows a comparatively more robust and compact morphology of the chondrocranium. This pattern is also evident in the mandibular arch, especially in the palatoquadrate. The present study is the first to describe the morphology of an orectolobiform shark species in detail using both manual dissection and micro-CT data. The resulting data furthermore provide a starting point for pending studies and are intended to be a first step in a series of comparative studies on the morphology of the cranial region of orectolobiform sharks, including the determination of possible sexual dimorphic characteristics.

Morphological and molecular characterization of Paraleptus chiloscyllii Yin & Zhang, 1983 (Nematoda: Physalopteridae) from the brownbanded bambooshark Chiloscyllium punctatum Müller & Henle (Elasmobranchii: Orectolobiformes).

Paraleptus (Spirurida: Physalopteridae) is a small genus of nematodes, parasitic in fishes, most species of which are inadequately described. Genetic data for these congeners have not been reported. The detailed morphology of P. chiloscyllii was studied using light and scanning electron microscopy, based on newly collected specimens from the brownbanded bambooshark C. punctatum Müller & Henle (Elasmobranchii: Orectolobiformes) in the Taiwan Strait. Some previously unreported morphological features of taxonomic significance were observed, i.e., pseudolabium with two sublateral rows of 6-7 small spines, 7-8 small spines on each lower rim between pseudolabia, deirids not distally bifurcated, vulva with remarkable protruding lip, presence of 1 pair medio-ventral precloacal papillae and 1 pair of discoid protrusions of postcloacal lip in male. The specimens described by González-Solís & Ali's (2015) as P. chiloscyllii from the Arabian carpetshark C. arabicum off Iraq are considered a new species, for which the name P. moraveci n. sp. is proposed. The genetic characterization of the partial small (18S) and large (28S) ribosomal DNA, and the partial mitochondrial cytochrome c oxidase subunit 1 (cox1) of P. chiloscyllii are provided for the first time. There was no intraspecific nucleotide divergence detected in the 18S and 28S regions among different individuals of P. chiloscyllii, but a low level of intraspecific genetic variation was found in the cox1 (0.62-0.92%). The present genetic data is very important for molecular identification, and will be valuable for further invertigantions on the population genetics and phylogeny of this group.

Early shape divergence of developmental trajectories in the jaw of galeomorph sharks

BackgroundThe onset of morphological differences between related groups can be tracked at early stages during embryological development. This is expressed in functional traits that start with minor variations, but eventually diverge to defined specific morphologies. Several processes during this period, like proliferation, remodelling, and apoptosis for instance, can account for the variability observed between related groups. Morphological divergence through development is often associated with the hourglass model, in which early stages display higher variability and reach a conserved point with reduced variability from which divergence occurs again to the final phenotype.ResultsHere we explored the patterns of developmental shape changes in the lower jaw of two shark species, the bamboo shark (Chiloscyllium punctatum) and the catshark (Scyliorhinus canicula). These two species present marked differences in their foraging behaviour, which is reflected in their adult jaw morphology. By tracing the developmental sequence of the cartilage condensation, we identified the onset of cartilage for both species at around stage 31. Other structures that developed later without a noticeable anlage were the labial cartilages, which appear at around stage 33. We observed that the lower jaw displays striking differences in shape from the earliest moments, without any overlap in shape through the compared stages.ConclusionsThe differences observed are also reflected in the functional variation in feeding mechanism between both species. Likewise, the trajectory analysis shows that the main differences are in the magnitude of the shape change through time. Both species follow a unique trajectory, which is explained by the timing between stages.

Brown banded bamboo shark (Chiloscyllium punctatum) shows high genetic diversity and differentiation in Malaysian waters

The demersal brown banded bamboo shark Chiloscyllium punctatum is a major component of sharks landed in Malaysia. However, little is known about their population structure and the effect of high fishing pressure on these weak swimming sharks. Both mitochondrial DNA control region (1072 bp) and NADH dehydrogenase subunit 2 (1044 bp) were used to elucidate the genetic structure and connectivity of C. punctatum among five major areas within the Sundaland region. Our findings revealed (i) strong genetic structure with little present day mixing between the major areas, (ii) high intra-population genetic diversity with unique haplotypes, (iii) significant correlation between genetic differentiation and geographical distance coupled with detectable presence of fine scale geographical barriers (i.e. the South China Sea), (iv) historical directional gene flow from the east coast of Peninsular Malaysia towards the west coast and Borneo, and (v) no detectable genetic differentiation along the coastline of east Peninsular Malaysia. Genetic patterns inferred from the mitochondrial DNA loci were consistent with the strong coastal shelf association in this species, the presence of contemporary barriers shaped by benthic features, and limited current-driven egg dispersal. Fine scale population structure of C. punctatum highlights the need to improve genetic understanding for fishery management and conservation of other small-sized sharks.

The Distribution Profile of Glycoconjugates in the Testis of Brown-Banded Bamboo Shark (Chiloscyllium punctatum) by Using Lectin Histochemistry.

The testis of bamboo shark is characterized by diametric development leading to zonation architecture. Here, we investigated the staining pattern of 12 lectins in 6 groups of differential binding specificities within the germ, somatic, and interstitial cells of each zone. The neutral mucopolysaccharides appeared in the interstitial tissue in all the zones and became more significant in the spermatozoal–Sertoli cell junction. The cellular localization of the lectins varies in testicular zones and cell types. There was a gradual increase in glycosylation toward the degenerative zone. The increased intensity of most lectins in the interstitial cells indicates the association of glycoconjugates in their androgen-secreting activity. Statistical analyses showed a significant correlation between the groups of lectins and each lectin used, stronger response to lectins in the interstitial cells (ICs) than other cell types. Moreover, the response to glucosamine (GlcNAc), galactosamine (GalNAc), and fucose tended to be higher than glucose and galactose. Furthermore, the intensity of response was increased toward the degenerative zone. In addition, we can use peanut agglutinin (PNA) as an acrosomal marker in combination with other marker proteins for studying shark spermatogenesis. These findings refer to the crucial role of glycoconjugates in spermatogenesis in the bamboo shark testis.

Delimiting cryptic species within the brown-banded bamboo shark, Chiloscyllium punctatum in the Indo-Australian region with mitochondrial DNA and genome-wide SNP approaches

BackgroundDelimiting cryptic species in elasmobranchs is a major challenge in modern taxonomy due the lack of available phenotypic features. Employing stand-alone genetics in splitting a cryptic species may prove problematic for further studies and for implementing conservation management. In this study, we examined mitochondrial DNA and genome-wide nuclear single nucleotide polymorphisms (SNPs) in the brown-banded bambooshark, Chiloscyllium punctatum to evaluate potential cryptic species and the species-population boundary in the group.ResultsBoth mtDNA and SNP analyses showed potential delimitation within C. punctatum from the Indo-Australian region and consisted of four operational taxonomic units (OTUs), i.e. those from Indo-Malay region, the west coast of Sumatra, Lesser Sunda region, and the Australian region. Each OTU can be interpreted differently depending on available supporting information, either based on biological, ecological or geographical data. We found that SNP data provided more robust results than mtDNA data in determining the boundary between population and cryptic species.ConclusionTo split a cryptic species complex and erect new species based purely on the results of genetic analyses is not recommended. The designation of new species needs supportive diagnostic morphological characters that allow for species recognition, as an inability to recognise individuals in the field creates difficulties for future research, management for conservation and fisheries purposes. Moreover, we recommend that future studies use a comprehensive sampling regime that encompasses the full range of a species complex. This approach would increase the likelihood of identification of operational taxonomic units rather than resulting in an incorrect designation of new species.

Age and growth of the tropical oviparous shark, Chiloscyllium punctatum in Indonesian waters.

The brown-banded bamboo shark, Chiloscyllium punctatum, is the most common shark caught in coastal commercial fisheries throughout Southeast Asia, yet there is a lack of the life-history information necessary for reliable stock assessments. The authors estimated growth rates and age at maturity using analysis of growth bands in vertebral centra. They trialled four different techniques to enhance the visibility and improve identification of the putative annual growth bands necessary for age estimation. The authors found that the burn method on whole vertebral centra provided the most readable and consistent results for age analysis. The logistic model was chosen as the best-fit growth model for age estimation of 330 individual C. punctatum from Indonesia. Several age verification methods, including marginal increment ratio and length-frequency analysis, were performed with the support of age validation through the use of calcein-labelled vertebrae from two sharks maintained in captivity. This study found that C. punctatum from Indonesian waters is a fast-growing species that can grow up to 18 cm year-1 , reach an estimated maximum total length of 1 m, mature at c. 6.5 years and live for up to 14 years.

Population structure of the brown-banded bamboo shark, Chiloscyllium punctatum and its relation to fisheries management in the Indo-Malay region

The brown-banded bamboo shark, Chiloscyllium punctatum is one of the most common shark species caught in coastal fisheries throughout the Indo-Malay region and the most abundant shark caught in trawl fisheries in Malaysia and Thailand. Differences in fisheries regulations related to trawling among jurisdictions, and an absence of either stock assessments or population estimates in the region, raise questions about the sustainability of fisheries that take this species. As a small-bodied, benthic shark that predominantly inhabits shallow, soft substrate habitats, the population may be particularly vulnerable to trawling throughout the region. We investigated the population structure of Chiloscyllium punctatum using genome-wide nuclear markers. Comprehensive DNA sampling was undertaken in Thailand, Malaysia and Indonesia, and population structure analysis using SNP datasets revealed at least four genetically distinct regional groups of C. punctatum. We identified a potentially shared stock between Malaysia and Indonesia, and separate populations in the Andaman Sea off Thailand, the South China Sea, and a localized population in South Sulawesi, Indonesia. Each of these stocks may likely require different management approaches tailored to the scale and types of fishing pressure in the different regions.

Developmental hourglass and heterochronic shifts in fin and limb development.

How genetic changes are linked to morphological novelties and developmental constraints remains elusive. Here, we investigate genetic apparatuses that distinguish fish fins from tetrapod limbs by analyzing transcriptomes and open-chromatin regions (OCRs). Specifically, we compared mouse forelimb buds with the pectoral fin buds of an elasmobranch, the brown-banded bamboo shark (Chiloscyllium punctatum). A transcriptomic comparison with an accurate orthology map revealed both a mass heterochrony and hourglass-shaped conservation of gene expression between fins and limbs. Furthermore, open-chromatin analysis suggested that access to conserved regulatory sequences is transiently increased during mid-stage limb development. During this stage, stage-specific and tissue-specific OCRs were also enriched. Together, early and late stages of fin/limb development are more permissive to mutations than middle stages, which may have contributed to major morphological changes during the fin-to-limb evolution. We hypothesize that the middle stages are constrained by regulatory complexity that results from dynamic and tissue-specific transcriptional controls.

Reproductive biology of a bamboo shark as a framework for better fisheries management

The brown-banded bamboo shark, Chiloscyllium punctatum, is one of the most common sharks caught in coastal fisheries across Southeast Asia; however, its small size and low economic value typically exclude it from the attention of fisheries managers. As part of an assessment of a potential role for this shark in improving the sustainability of coastal shark fisheries in Indonesia, we investigated its reproductive biology from waters around the Seribu Islands on the basis of monthly sampling from a fish landing in Tanjung Pasir, Banten. Females have fully functional uteri, but asymmetric ovaries, with only the right ovary being functional and the left ovary being atrophied. The species is reproductively active throughout the year, with the optimum period for males to copulate being from June to August, and the optimum period for egg-laying in females from July to January on the basis of their physiological condition. Females mature at a larger size than do males, 704- and 653-mm total length respectively. To allow a continuous recruitment flow to the population, and to facilitate compliance and monitoring, we recommend that fishers release all brown-banded bamboo sharks greater than 700mm in total length.

Sexual development and maturity of the male brown banded bamboo shark,

The present study aimed to assess the reproductive biology of male brown banded bamboo shark (Chiloscyllium punctatum). Morphological and histological changes in the reproductive tract and changes in gonad steroid testosterone were assessed in 110 male C. punctatum collected from Bahrakan Creek between January 2018 and March 2019. The reproductive tract in male C. punctatum consisted of a pair of testes, efferent ducts, epididymidis, ductus deferens, seminal vesicles, Leydig gland and claspers. Four sexual development stages were determined: (1) immature, no calcified claspers (2) maturing, partially calcified claspers; (3) active and resting adults. Both adult resting and active stages had calcified claspers. In this study, immature male C. punctatum without calcified claspers were found from August to October, maturing C. punctatum with partially calcified claspers were found from November to January and adult C. punctatum caught from February to April were active with calcified claspers, whereas adult fish collected from May to July and during the rest of the year (until mid-January in the following year) were in the resting stage with inactive testes. The testis had a lobular structure and the spermatocysts were arranged diametrically (i.e. along the cross-sectional width of the testis) in each lobule. Plasma testosterone concentrations were associated with histomorphological changes in the reproductive tract. Testosterone concentrations peaked in March in active males and then decreased significantly in resting males. Overall, the variations in the reproductive organs during different sexual maturity stages were consistent with their roles in the production, movement and release of spermatozoa.