Connecting post-release mortality to the physiological stress response of large coastal sharks in a commercial longline fishery.

Bycatch mortality is a major factor contributing to shark population declines. Post-release mortality (PRM) is particularly difficult to quantify, limiting the accuracy of stock assessments. We paired blood-stress physiology with animal-borne accelerometers to quantify PRM rates of sharks caught in a commercial bottom longline fishery. Blood was sampled from the same individuals that were tagged, providing direct correlation between stress physiology and animal fate for sandbar (Carcharhinus plumbeus, N = 130), blacktip (C. limbatus, N = 105), tiger (Galeocerdo cuvier, N = 52), spinner (C. brevipinna, N = 14), and bull sharks (C. leucas, N = 14). PRM rates ranged from 2% and 3% PRM in tiger and sandbar sharks to 42% and 71% PRM in blacktip and spinner sharks, respectively. Decision trees based on blood values predicted mortality with >67% accuracy in blacktip and spinner sharks, and >99% accuracy in sandbar sharks. Ninety percent of PRM occurred within 5 h after release and 59% within 2 h. Blood physiology indicated that PRM was primarily associated with acidosis and increases in plasma potassium levels. Total fishing mortality reached 62% for blacktip and 89% for spinner sharks, which may be under-estimates given that some soak times were shortened to focus on PRM. Our findings suggest that no-take regulations may be beneficial for sandbar, tiger, and bull sharks, but less effective for more susceptible species such as blacktip and spinner sharks.

International fisheries threaten globally endangered sharks in the Eastern Tropical Pacific Ocean: the case of the Fu Yuan Yu Leng 999 reefer vessel seized within the Galápagos Marine Reserve.

Shark fishing, driven by the fin trade, is the primary cause of global shark population declines. Here, we present a case study that exemplifies how industrial fisheries are likely depleting shark populations in the Eastern Tropical Pacific Ocean. In August 2017, the vessel Fu Yuan Yu Leng 999, of Chinese flag, was detained while crossing through the Galápagos Marine Reserve without authorization. This vessel contained 7639 sharks, representing one of the largest seizures recorded to date. Based on a sample of 929 individuals (12%), we found 12 shark species: 9 considered as Vulnerable or higher risk by the IUCN and 8 listed in CITES. Four species showed a higher proportion of immature than mature individuals, whereas size-distribution hints that at least some of the fishing ships associated with the operation may have been using purse-seine gear fishing equipment, which, for some species, goes against international conventions. Our data expose the magnitude of the threat that fishing industries and illegal trade represent to sharks in the Eastern Tropical Pacific Ocean.

Red and white muscle proportions and enzyme activities in mesopelagic sharks.

In the last decade, there has been an increase in the study of the ecology of deep-sea organisms. One way to understand an organism's ecology is the study of its metabolism. According to literature, deep-sea sharks possess a lower anaerobic enzyme activity than their shallow-water counterparts, but no difference has been observed regarding their aerobic enzyme activities. These studies have suggested deep-sea sharks should be slow and listless swimmers. However, other studies based on video observations have revealed differences in cruise swimming speed between different species. The present study examined muscles of squaliform sharks, including both luminous and non-luminous species. We combined measurements of the relative amounts of red and white muscle with assays of enzymes that are used as markers for aerobic (citrate synthase, malate dehydrogenase) and anaerobic (lactate dehydrogenase) metabolism, searching for a relationship with cruising speeds. Non-luminous deep-sea species displayed lower aerobic enzyme activities but similar anaerobic enzyme activities than the benthic shallow-water counterpart (Squalus acanthias). Conversely, luminous Etmopteridae species were found to have similar aerobic enzyme activities to S. acanthias but displayed lower anaerobic enzyme activities. Analyses revealed that red muscle proportion and aerobic enzyme activities were positively related to the cruise swimming speed. In contrast, Dalatias licha, which swims at the slowest cruise swimming speed ever recorded, presented a very low aerobic metabolic phenotype (lower aerobic marker enzymes and less red muscle). Finally, the values obtained for white muscle proportion and anaerobic metabolic phenotype suggested a high burst capacity for D. licha and non-luminous sharks.

Modernising fish and shark growth curves with Bayesian length-at-age models.

Growth modelling is a fundamental component of fisheries assessments but is often hindered by poor quality data from biased sampling. Several methods have attempted to account for sample bias in growth analyses. However, in many cases this bias is not overcome, especially when large individuals are under-sampled. In growth models, two key parameters have a direct biological interpretation: L0, which should correspond to length-at-birth and L∞, which should approximate the average length of full-grown individuals. Here, we present an approach of fitting Bayesian growth models using Markov Chain Monte Carlo (MCMC), with informative priors on these parameters to improve the biological plausibility of growth estimates. A generalised framework is provided in an R package 'BayesGrowth', which removes the hurdle of programming an MCMC model for new users. Four case studies representing different sampling scenarios as well as three simulations with different selectivity functions were used to compare this Bayesian framework to standard frequentist growth models. The Bayesian models either outperformed or matched the results of frequentist growth models in all examples, demonstrating the broad benefits offered by this approach. This study highlights the impact that Bayesian models could provide in age and growth studies if applied more routinely rather than being limited to only complex or sophisticated applications.

Future thermal regimes for epaulette sharks (Hemiscyllium ocellatum): growth and metabolic performance cease to be optimal.

Climate change is affecting thermal regimes globally, and organisms relying on their environment to regulate biological processes face unknown consequences. In ectotherms, temperature affects development rates, body condition, and performance. Embryonic stages may be the most vulnerable life history stages, especially for oviparous species already living at the warm edge of their distribution, as embryos cannot relocate during this developmental window. We reared 27 epaulette shark (Hemiscyllium ocellatum) embryos under average summer conditions (27 °C) or temperatures predicted for the middle and end of the twenty-first century with climate change (i.e., 29 and 31 °C) and tracked growth, development, and metabolic costs both in ovo and upon hatch. Rearing sharks at 31 °C impacted embryonic growth, yolk consumption, and metabolic rates. Upon hatch, 31 °C-reared sharks weighed significantly less than their 27 °C-reared counterparts and exhibited reduced metabolic performance. Many important growth and development traits in this species may peak after 27 °C and start to become negatively impacted nearing 31 °C. We hypothesize that 31 °C approximates the pejus temperature (i.e., temperatures at which performance of a trait begin to decline) for this species, which is alarming, given that this temperature range is well within ocean warming scenarios predicted for this species' distribution over the next century.

Ontogenetic Shifts in Brain Size and Brain Organization of the Atlantic Sharpnose Shark, Rhizoprionodon terraenovae.

Throughout an animal's life, species may occupy different environments and exhibit distinct life stages, known as ontogenetic shifts. The life histories of most sharks (class: Chondrichthyes) are characterized by these ontogenetic shifts, which can be defined by changes in habitat and diet as well as behavioral changes at the onset of sexual maturity. In addition, fishes experience indeterminate growth, whereby the brain and body grow throughout the organism's life. Despite a presupposed lifelong neurogenesis in sharks, very little work has been done on ontogenetic changes in the brain, which may be informative about functional shifts in sensory and behavioral specializations. This study quantified changes in brain-body scaling and the scaling of six major brain regions (olfactory bulbs, telencephalon, diencephalon, optic tectum, cerebellum, and medulla oblongata) throughout ontogeny in the Atlantic sharpnose shark, Rhizoprio-nodon terraenovae. As documented in other fishes, brain size increased significantly with body mass throughout ontogeny in this species, with the steepest period of growth in early life. The telencephalon, diencephalon, optic tectum, and medulla oblongata scaled with negative allometry against the rest of the brain throughout ontogeny. However, notably, the olfactory bulbs and cerebellum scaled hyperallometrically to the rest of the brain, whereby these structures enlarged disproportionately as this species matured. Changes in the relative size of the olfactory bulbs throughout ontogeny may reflect an increased reliance on olfaction at later life history stages in R. terraenovae, while changes in the relative size of the cerebellum throughout ontogeny may be indicative of the ability to capture faster prey or an increase in migratory nature as this species moves to offshore habitats, associated with the onset of sexual maturity.

Assessing the reproductive biology of the Greenland shark (Somniosus microcephalus).

The Greenland shark (Somniosus microcephalus, Squaliformes: Somniosidae) is a long-lived Arctic top predator, which in combination with the high historical and modern fishing pressures, has made it subject to increased scientific focus in recent years. Key aspects of reproduction are not well known as exemplified by sparse and contradictory information e.g. on birth size and number of pups per pregnancy. This study represents the first comprehensive work on Greenland shark reproductive biology based on data from 312 specimens collected over the past 60 years. We provide guidelines quantifying reproductive parameters to assess specific maturation stages, as well as calculate body length-at-maturity (TL50) which was 2.84±0.06 m for males and 4.19±0.04 m for females. From the available information on the ovarian fecundity of Greenland sharks as well as a meta-analysis of Squaliform reproductive parameters, we estimate up to 200-324 pups per pregnancy (depending on maternal size) with a body length-at-birth of 35-45 cm. These estimates remain to be verified by future observations from gravid Greenland sharks.

Evolution of vertebrate gill covers via shifts in an ancient Pou3f3 enhancer.

Whereas the gill chambers of jawless vertebrates open directly into the environment, jawed vertebrates evolved skeletal appendages that drive oxygenated water unidirectionally over the gills. A major anatomical difference between the two jawed vertebrate lineages is the presence of a single large gill cover in bony fishes versus separate covers for each gill chamber in cartilaginous fishes. Here, we find that these divergent patterns correlate with the pharyngeal arch expression of Pou3f3 orthologs. We identify a deeply conserved Pou3f3 arch enhancer present in humans through sharks but undetectable in jawless fish. Minor differences between the bony and cartilaginous fish enhancers account for their restricted versus pan-arch expression patterns. In zebrafish, mutation of Pou3f3 or the conserved enhancer disrupts gill cover formation, whereas ectopic pan-arch Pou3f3b expression generates ectopic skeletal elements resembling the multimeric covers of cartilaginous fishes. Emergence of this Pou3f3 arch enhancer >430 Mya and subsequent modifications may thus have contributed to the acquisition and diversification of gill covers and respiratory strategies during gnathostome evolution.

Novel developmental bases for the evolution of hypobranchial muscles in vertebrates.

BACKGROUND: Vertebrates are characterized by possession of hypobranchial muscles (HBMs). Cyclostomes, or modern jawless vertebrates, possess a rudimentary and superficial HBM lateral to the pharynx, whereas the HBM in jawed vertebrates is internalized and anteroposteriorly specified. Precursor cells of the HBM, marked by expression of Lbx1, originate from somites and undergo extensive migration before becoming innervated by the hypoglossal nerve. How the complex form of HBM arose in evolution is relevant to the establishment of the vertebrate body plan, but despite having long been assumed to be similar to that of limb muscles, modification of developmental mechanisms of HBM remains enigmatic. RESULTS: Here we characterize the expression of Lbx genes in lamprey and hagfish (cyclostomes) and catshark (gnathostome; jawed vertebrates). We show that the expression patterns of the single cyclostome Lbx homologue, Lbx-A, do not resemble the somitic expression of mammalian Lbx1. Disruption of Lbx-A revealed that LjLbx-A is required for the formation of both HBM and body wall muscles, likely due to the insufficient extension of precursor cells rather than to hindered muscle differentiation. Both homologues of Lbx in the catshark were expressed in the somitic muscle primordia, unlike in amniotes. During catshark embryogenesis, Lbx2 is expressed in the caudal HBM as well as in the abdominal rectus muscle, similar to lamprey Lbx-A, whereas Lbx1 marks the rostral HBM and pectoral fin muscle. CONCLUSIONS: We conclude that the vertebrate HBM primarily emerged as a specialized somatic muscle to cover the pharynx, and the anterior internalized HBM of the gnathostomes is likely a novelty added rostral to the cyclostome-like HBM, for which duplication and functionalization of Lbx genes would have been a prerequisite.

Ontogenetic trophic segregation between two threatened smooth-hound sharks in the Central Mediterranean Sea.

Elasmobranchs are among the species most threatened by overfishing and a large body of evidence reports their decline around the world. As they are large predators occupying the highest levels of marine food webs, their removal can alter the trophic web dynamic through predatory release effects and trophic cascade. Suitable management of threatened shark species requires a good understanding of their behaviour and feeding ecology. In this study we provide one of the first assessments of the trophic ecology of the "vulnerable" smooth-hounds Mustelus mustelus and M. punctulatus in the Central Mediterranean Sea, based on stomach contents and stable isotope analyses. Ontogenetic diet changes were addressed by comparing the feeding habits of three groups of individuals: juveniles, maturing and adults. Our results highlighted that the two species share a similar diet based mostly on the consumption of benthic crustaceans (e.g. hermit crabs). Their trophic level increases during ontogeny, with adults increasing their consumption of large-sized crustaceans (e.g. Calappa granulata, Palinurus elephas), cephalopods (e.g. Octopus vulgaris) and fish (e.g. Trachurus trachurus). Our results provide also evidence of ontogenetic shifts in diet for both species showing a progressive reduction of interspecific trophic overlap during growth. The results of this study contribute to improve the current knowledge on the trophic ecology of these two threatened sharks in the Strait of Sicily, thus providing a better understanding of their role in the food web.

Identification of a nursery area for the critically endangered hammerhead shark (Sphyrna lewini) amid intense fisheries in the southern Gulf of Mexico.

Since the 1980s, there has been growing concern in the Mexican Atlantic regarding high catches of neonate and juvenile sharks in small-scale fisheries. Fishery-dependent data from 1993 to 1994 and 2007 to 2017 and fishers' ecological knowledge from 2017 were used to identify nursery areas for scalloped hammerhead, Sphyrna lewini, in the southern Gulf of Mexico. Catch records and fishing areas of neonates, YOYs, juveniles and adults of S. lewini (N = 1885) were obtained from calcareous and terrigenous regions in the western Yucatan Peninsula. The results suggest that a nursery for scalloped hammerhead is found in the terrigenous region, characterized by relatively shallow and turbid waters due to rivers' discharges. Neonates and YOYs (96% and 86% of their total records, respectively) were commonly found there over the years in May-August in multiple fishing areas identified by fishers, although mainly between isobaths 10-30 m. The enforcement of management measures is necessary because the nursery is located in a region with intense fishing effort.

The intraspecific diversity of tooth morphology in the large-spotted catshark Scyliorhinus stellaris: insights into the ontogenetic cues driving sexual dimorphism.

Teeth in sharks are shed and replaced throughout their lifetime. Morphological dental changes through ontogeny have been identified in several species and have been correlated with shifts in diet and the acquisition of sexual maturity. However, these changes were rarely quantified in detail along multiple ontogenetic stages, which makes it difficult to infer the developmental processes responsible for the observed plasticity. In this work, we use micro-computed tomography and 3D geometric morphometrics to describe and analyze the tooth size and shape diversity across three ontogenetic stages (hatchling, juvenile, and sexually mature) in the large-spotted catshark Scyliorhinus stellaris (Linnaeus, 1758). We first describe the intra-individual variation of tooth form for each sex at each ontogenetic stage. We provide a tooth morphospace for palatoquadrate and Meckelian teeth and identify dental features, such as relative size and number of cusps, involved in the range of variation of the observed morphologies. We then use these shape data to draw developmental trajectories between ontogenetic stages and for each tooth position within the jaw to characterize ontogenetic patterns of sexual dimorphism. We highlight the emergence of gynandric heterodonty between the juvenile and mature ontogenetic stages, with mature females having tooth morphologies more similar to juveniles' than mature males that display regression in the number of accessory cusps. From these data, we speculate on the developmental processes that could account for such developmental plasticity in S. stellaris.

Movement patterns and habitat use of tiger sharks (Galeocerdo cuvier) across ontogeny in the Gulf of Mexico.

The tiger shark (Galeocerdo cuvier) is globally distributed with established coastal and open-ocean movement patterns in many portions of its range. While all life stages of tiger sharks are known to occur in the Gulf of Mexico (GoM), variability in habitat use and movement patterns over ontogeny have never been quantified in this large marine ecosystem. To address this data gap we fitted 56 tiger sharks with Smart Position and Temperature transmitting tags between 2010 and 2018 and examined seasonal and spatial distribution patterns across the GoM. Additionally, we analyzed overlap of core habitats (i.e., 50% kernel density estimates) among individuals relative to large benthic features (oil and gas platforms, natural banks, bathymetric breaks). Our analyses revealed significant ontogenetic and seasonal differences in distribution patterns as well as across-shelf (i.e., regional) and sex-linked variability in movement rates. Presumably sub-adult and adult sharks achieved significantly higher movement rates and used off-shelf deeper habitats at greater proportions than juvenile sharks, particularly during the fall and winter seasons. Further, female maximum rate of movement was higher than males when accounting for size. Additionally, we found evidence of core regions encompassing the National Oceanographic and Atmospheric Administration designated Habitat Areas of Particular Concern (i.e., shelf-edge banks) during cooler months, particularly by females, as well as 2,504 oil and gas platforms. These data provide a baseline for future assessments of environmental impacts, such as climate variability or oil spills, on tiger shark movements and distribution in the region. Future research may benefit from combining alternative tracking tools, such as acoustic telemetry and genetic approaches, which can facilitate long-term assessment of the species' movement dynamics and better elucidate the ecological significance of the core habitats identified here.

Articulated remains of the extinct shark Ptychodus (Elasmobranchii, Ptychodontidae) from the Upper Cretaceous of Spain provide insights into gigantism, growth rate and life history of ptychodontid sharks.

Due to their cartilaginous endoskeleton and the continuous tooth replacement, the chondrichthyan fossil record predominantly consists of isolated teeth, which offer diagnostic features for taxonomic identifications, but only provide very limited information of an organism's life history. In contrast, the calcified vertebral centra of elasmobranchs (sharks, skates and rays) yield important information about ecological and biological traits that can be utilized for constructing age-structured population dynamic models of extant species and palaeoecological reconstructions of such aspects in extinct groups. Here, we describe two large shark vertebrae from the Santonian (Upper Cretaceous) of Spain, which show a unique combination of characters (asterospondylic calcification pattern, with concentric lamellae and numerous parallel bands that are oriented perpendicular) that is only known from ptychodontid sharks, a distinct, extinct group of giant durophagous sharks of the Cretaceous era. Based on linear regression models for large extant sharks a total length between 430 and 707cm was estimated for the examined specimen. Our results indicate that ptychodontid sharks were large viviparous animals, with slow growth rates, matured very late and, therefore, show typical traits for K-selected species. These traits combined with a highly specialized feeding ecology might have played a crucial role for the success but also, eventually, extinction of this group.

Non-lethal assessment of reproductive stage for female blue sharks Prionace glauca using sex steroid hormones.

Plasma concentrations of progesterone (P4 ) and 17ß-oestradiol (E2 ) in juvenile, pre-ovulatory, early, mid- or late pregnancy stages of female blue sharks Prionace glauca were analysed. Concentrations of P4 were significantly higher in pregnant than in non-pregnant individuals, whereas E2 concentrations increased with embryonic and follicular development. A highly accurate (86.1%) random forest classification model was developed to predict shark pregnancy. It is proposed that hormone concentrations could be used for the subsequent non-lethal determination of female P. glauca reproductive state.

Holocephalan (Chondrichthyes) dental plates with hypermineralized dentine as a substitute for missing teeth through developmental plasticity.

All extant holocephalans (Chimaeroidei) have lost the ability to make individual teeth, as tooth germs are not part of the embryonic development of the dental plates or of their continuous growth. Instead, a hypermineralized dentine with a unique mineral, whitlockin, is specifically distributed within a dentine framework into structures that give the dental plates their distinctive, species-specific morphology. Control of the regulation of this distribution must be cellular, with a dental epithelium initiating the first outer dentine, and via contact with ectomesenchymal tissue as the only embryonic cell type that can make dentine. Chimaeroids have three pairs of dental plates within their mouth, two in the upper jaw and one in the lower. In the genera Chimaera, Hydrolagus and Harriotta, the morphology and distribution of this whitlockin within each dental plate differs both between different plates in the same species and between species. Whitlockin structures include ovoids, rods and tritoral pads, with substantial developmental changes between these. For example, rods appear before the ovoids and result from a change in the surrounding trabecular dentine. In Harriotta, ovoids form separately from the tritoral pads, but also contribute to tritor development, while in Chimaera and Hydrolagus, tritoral pads develop from rods that later are perforated to accommodate the vasculature. Nevertheless, the position of these structures, secreted by the specialized odontoblasts (whitloblasts), appears highly regulated in all three species. These distinct morphologies are established at the aboral margin of the dental plate, with proposed involvement of the outer dentine. We observe that this outer layer forms into serially added lingual ridges, occurring on the anterior plate only. We propose that positional, structural specificity must be contained within the ectomesenchymal populations, as stem cells below the dental epithelium, and a coincidental occurrence of each lingual, serial ridge with the whitlockin structures that contribute to the wear-resistant oral surface.

Presence of the protein indoleamine 2,3-dioxygenase (IDO) in the maternal-fetal interface of the yolk sac placenta of blue shark, Prionace glauca.

Indoleamine 2 3-dioxygenase (IDO) is a protein usually described in mammals, which, among other functions, participates in the maternal-fetal tolerance process. The blue-shark, Prionace glauca (Linnaeus, 1758) is a viviparous placentary species in which the yolk sac develops during the pregnancy, turning into a placenta for matrotrophic nutrition of the embryo. The purpose of this study was to investigate the expression of IDO in the P. glauca maternal-fetal interface along three gestation phases and describe its distribution and the meaning of its presence. The results showed IDO labelling during the yolk sac/placenta development in the ectoderm on the three development phases and in the endoderm at the two first phases. In the uterine epithelium, IDO was observed in the last two phases. These interface tissues are major contact areas between the mother and the semiallogeneic conceptus and this relation could induce an immunological response against the fetus. Therefore, the presence of IDO may indicate that it could have a similar role in the mechanism of maternal-fetal tolerance in the P. glauca placental interface, as described in eutherian mammals.

Characterization of neurogenic niches in the telencephalon of juvenile and adult sharks.

Neurogenesis is a multistep process by which progenitor cells become terminally differentiated neurons. Adult neurogenesis has gathered increasing interest with the aim of developing new cell-based treatments for neurodegenerative diseases in humans. Active sites of adult neurogenesis exist from fish to mammals, although in the adult mammalian brain the number and extension of neurogenic areas is considerably reduced in comparison to non-mammalian vertebrates and they become mostly reduced to the telencephalon. Much of our understanding in this field is based in studies on mammals and zebrafish, a modern bony fish. The use of the cartilaginous fish Scyliorhinus canicula (representative of basal gnathostomes) as a model expands the comparative framework to a species that shows highly neurogenic activity in the adult brain. In this work, we studied the proliferation pattern in the telencephalon of juvenile and adult specimens of S. canicula using antibodies against the proliferation marker proliferating cell nuclear antigen (PCNA). We have characterized proliferating niches using stem cell markers (Sex determining region Y-box 2), glial markers (glial fibrillary acidic protein, brain lipid binding protein and glutamine synthase), intermediate progenitor cell markers (Dlx2 and Tbr2) and markers for migrating neuroblasts (Doublecortin). Based in the expression pattern of these markers, we demonstrate the existence of different cell subtypes within the PCNA immunoreactive zones including non-glial stem cells, glial progenitors, intermediate progenitor-like cells and migratory neuroblasts, which were widely distributed in the ventricular zone of the pallium, suggesting that the main progenitor types that constitute the neurogenic niche in mammals are already present in cartilaginous fishes.

Periodicity of the growth-band formation in vertebrae of juvenile scalloped hammerhead shark Sphyrna lewini from the Mexican Pacific Ocean.

The age of 296 juvenile scalloped hammerhead sharks Sphyrna lewini caught by several fisheries in the Mexican Pacific Ocean from March 2007 to September 2017 were estimated from growth band counts in thin-sectioned vertebrae. Marginal-increment analysis (MIA) and centrum-edge analysis (CEA) were used to verify the periodicity of formation of the growth bands, whereas elemental profiles obtained from LA-ICP-MS transect scans in vertebrae of 15 juveniles were used as an alternative approach to verify the age of the species for the first time. Age estimates ranged from 0 to 10+ years (42-158.7 cm total length; LT ). The index of average percentage error (IAPE 3.6%), CV (5.2%), bias plots and Bowker's tests of symmetry showed precise and low-biased age estimation. Both MIA and CEA indicated that in the vertebrae of juveniles of S. lewini a single translucent growth band was formed during winter (November-March) and an opaque band during summer (July-September), a period of faster growth, apparently correlated with a higher sea surface temperature. Peaks in vertebral P and Mn content spatially corresponded with the annual banding pattern in most of the samples, displaying 1.19 and 0.88 peaks per opaque band, respectively, which closely matched the annual deposition rate observed in this study. Although the periodicity of growth band formation needs to be verified for all sizes and ages representing the population of the species in the region, this demonstration of the annual formation of the growth bands in the vertebrae of juveniles should lead to a re-estimation of the growth parameters and productivity of the population to ensure that it is harvested at sustainable levels.

Captive parturition and neonatal growth of the dwarf ornate wobbegong (Orectolobus ornatus de Vis, 1883).

Neonatal predation in multispecies aquarium exhibits can prevent detection of captive breeding by wobbegong sharks. We used ultrasonography and isolation strategies to prevent neonatal predation and maximize survival/growth of the dwarf ornate wobbegong (Orectolobus ornatus de Vis, 1883). We captured seven free-living wobbegongs (two males and five females) and subjected each animal to a health assessment which led to the euthanasia of one female with a retained hook. Ultrasonography showed that females were pregnant, one was preovulatory, and one was in a resting phase. Two females (one pregnant) and one male were placed in isolation in each of two tanks. In October 2006, 25 neonates were born overnight with the two litters placed into separate neonate tanks. Over the ∼6.5-month monitoring period, four neonates with reduced body condition died without premonitory signs resulting in a 63.0% annual survival rate. Finite growth rates did not differ between sexes or litters and averaged (±SE) 12.2 (1.5) cm/year and 156.4 (26.4) g/year. At the cessation of monitoring, total length had increased by ∼30%, whereas total weight had almost doubled with neonatal body condition in line with free-living wobbegongs. Our efficacious, six-step manipulative, the approach should be applicable with all wobbegongs given their reproductive similarities, but we recommend that efforts focus on the dwarf ornate, tasselled and Japanese wobbegongs because all are small in size and have bred in aquaria. Ultimately, this approach should produce self-sustaining aquarium populations, place less reliance on the wild acquisition and provide animals for other aquaria, population restocking, or scientific research.