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Many shark species form groups; yet the drivers of this behaviour are not well understood. Aggregations have been presumed to be a function of resource availability or phenology. However, recent studies have suggested that some sharks display preferences in their associations with conspecifics and that complex social networks may underpin their movement patterns, demographic distribution and fitness. This study used a network approach to investigate patterns of sociality of a benthic predator, the spotted wobbegong shark, Orectolobus maculatus (Family Orectolobidae), in a small marine reserve. Spatial data obtained from fine-scale passive acoustic telemetry were used to infer association preferences of 15 tagged sharks over a 15-month period. Thirty-five associating dyads emerged, with permutation tests indicating that these were nonrandomly formed. Many dyads were temporally stable, with some persisting even after sharks returned to the reserve from their seasonal migration. A complete but sparse network was observed and although association patterns were evident at the dyadic level, indication of stable communities or network structure was limited. The population was not found to be gregarious and exclusive pairs were not observed, with 14 sharks associating with more than one individual. Assortative mixing (by sex, size and familiarity) was not present and range overlap did not strongly correlate with association indices. This suggests that these relationships are not a random result of nonsocial grouping behaviours but can be explained, at least in part, by genuine social affiliation. As such, anthropogenic influences on the population may have more complex impacts than previously thought.

Demersal elasmobranchs are ecologically important mesopredators but little is known about their population connectivity or dispersal patterns. Here we use a comparative approach based on mitochondrial DNA and nuclear amplified fragment length polymorphism (AFLP) markers to examine spatial genetic structure and dispersal in three closely related demersal elasmobranchs from eastern Australia: Orectolobus halei, Orectolobus maculatus, and Orectolobus ornatus. We found evidence of significant spatial genetic structure, possibly indicating regional philopatry in wobbegongs. The molecular data also indicate that dispersal in wobbegongs may be sex-biased. This represents the first genetic study of dispersal and population connectivity in codistributed demersal sharks. It provides insights into the ecology of dispersal behaviours with implications for conservation management of demersal species.

Much is known regarding the evolution of colour vision in nearly every vertebrate class, with the notable exception of the elasmobranchs. While multiple spectrally distinct cone types are found in some rays, sharks appear to possess only a single class of cone and, therefore, may be colour blind. In this study, the visual opsin genes of two wobbegong species,Orectolobus maculatusandOrectolobus ornatus, were isolated to verify the molecular basis of their monochromacy. In both species, only two opsin genes are present,RH1(rod) andLWS(cone), which provide further evidence to support the concept that sharks possess only a single cone type. Examination of the coding sequences revealed substitutions that account for interspecific variation in the photopigment absorbance spectra, which may reflect the difference in visual ecology between these species.

Comparative studies of the mechanosensory lateral line (MLL) have provided valuable insights into the predatory, escape and navigation behaviours of teleost and elasmobranch fishes. Recent work on the MLL in elasmobranchs has focused on canal morphology and pore topography in batoid species, with considerably less detailed examination of the canal system of sharks. In this study, the spatial arrangement of MLL canals and pit organs, and the morphology of the sensory neuromasts, are described for two species of wobbegong shark: the spotted wobbegong Orectolobus maculatus and the ornate wobbegong O. ornatus. Wobbegongs are benthic species that employ an ambush feeding strategy, and it is hypothesised that the MLL will be adapted for both these ecological traits. The spatial distribution of the MLL system in both species is broadly similar to other elasmobranchs, with a dorsal concentration of canals and pit organs that is ideally suited for detecting water flow over the top of the head. This arrangement may facilitate the detection of prey and predators swimming above and in front of the shark. The non-pored canals positioned directly above the mouth may be used as mechanotactile receptors to optimise ‘touch’ sensation when feeding. Wobbegong canal and pit organ neuromast hair cell morphology is typical of other sharks; however, canal neuromast sensory tissue differs from other elasmobranch species in that it is not continuous throughout the canals. The study provides evidence that the MLL system of wobbegong sharks is well adapted for their rather unique feeding mode and benthic lifestyle.

The present study used wobbegong sharks (genus Orectolobus) to assess the threshold value proposed by previous research to categorize strict lecithotrophic from incipient histotrophic species. Totals of 236 and 135 ornate wobbegong Orectolobus ornatus and spotted wobbegong Orectolobus maculatus, respectively, were collected from the New South Wales commercial fishery between June 2003 and May 2006. Eight pregnant gulf wobbegong Orectolobus halei were also recorded outside the sampling period for the first time. The three species were reproductively synchronous with a gestation of c. 10-11 months. Embryos started to be macroscopically visible during January and external yolk sacs were fully absorbed by June to July when embryos were c. 200 mm total length (L(T) ). Internal yolk sacs were first observed during April to May when embryos were c. 160 mm L(T) , reached a peak during June and persisted in embryos immediately prior to parturition. The total wet mass from uterine egg to full-term embryos increased by 44-89% and 45-62%, whereas the total organic mass decreased by 32-33% and 26%, for O. ornatus and O. maculatus, respectively, suggesting that these species are strict lecithotrophic yolk-sac viviparous sharks with no maternal nutrient input. A review of the literature identified various issues and suggested that the previously proposed organic mass loss threshold value separating strict lecithotrophic species from incipient histotrophic species might not be appropriate. Instead, it is recommended that a combination of methods (e.g. estimation of organic mass gain or loss between ovarian egg and developed embryo, histology and electron microscopy of the uterus, radio-tracer assay and uterine fluid analysis throughout gestation) is used to discern between strict lecithotrophic and incipient histotrophic species.

Wobbegongs are benthic sharks that are commercially targeted in New South Wales (NSW), Australia. Given a dramatic reduction of more than 50% in landed catch in a decade, there is a clear need to ensure that basic ecological data such as distribution and abundance are available for management use. Opportunistic sightings of wobbe- gongs collected by recreational scuba-divers were used to assess the distribution and relative abundance of wobbegongs in NSW. From July 2003 until January 2005, 304 dives were undertaken by recreational divers and 454 wobbegongs were reported. Larger numbers of wobbegongs were sighted in northern compared to southern NSW. Spotted and ornate wobbegongs were sighted in similar numbers, but species composition was highly variable across locations. Only a few juvenile and newborn spotted wobbegongs were sighted, whereas small ornate wobbegongs were mostly sighted north of central NSW. The latter were possibly the third, cryptic species, the dwarf ornate wobbegong. The paucity of sight- ings of small wobbegongs suggests that juveniles and newborns are inconspicuous to divers or that small wobbegongs are found in areas not visited by divers. Potential species and size segregation suggest that closing areas to fishing may enable populations to sustain current levels of commercial exploitation. The cost-effectiveness of using recre- ational scuba-divers to opportunistically collect distribution and relative abundance data was apparent from this study. However, the lack of spatial and temporal homogeneity in diving effort suggests that future studies should consider incorporating organized surveys and a facilitator, rather than using opportunistic records of sightings.

This study reports on evidence for reproductive isolation among Orectolobus ornatus and Orectolobus halei, two previously cryptic and recently redescribed species of wobbegong shark (Orectolobiformes: Orectolobidae) from the east coast of Australia. The evidence is based on disparity in size at sexual maturity, diagnostic nuclear and mitochondrial DNA variants, and marked phylogenetic divergence. Plots of total length (LT) and maturity for the two species were non-overlapping and illustrative of statistically significant size dimorphism. Genetic analyses and phylogenetic reconstruction did not provide indication of hybridization between O. ornatus and O. halei. In fact, sequence divergence between them was higher than in comparisons with another congeneric and largely co-distributed wobbegong species (Orectolobus maculatus). The assumption of a molecular clock revealed that the two species have evolved in isolation for c. 3� 9 million years. These results challenge a paradigm often mentioned in the biodiversity literature that most cryptic species are the product of recent speciation events and will contribute to the development of effective management strategies for wobbegong sharks. # 2008 The Authors Journal compilation # 2008 The Fisheries Society of the British Isles

The wobbegong genus Orectolobus occurring from Japan and its adjacent waters was reviewed, and O. japonicus was redescribed using ten specimens including a syntype. Only one species, O. japonicus, was regarded as valid among three species previously recorded from Japan. Orectolobus maculatus had been erroneously described from Japan because of the past nomenclatural confusion with O. japonicus. The specimen called “Karakusa-oose,” which had been identified with O. ornatus, was regarded as an irregular form of O. japonicus. Orectolobus japonicus was distinguished from the other congeners by having no tubercles on the body, five to eight dermal lobes in the preorbital group, two distally notched lobes in the postspiracular group, no dermal lobes on lower jaw, nasal barbel with a branch, no supraocular knob, relatively high dorsal fins with usually concave posterior margins, a lower number of precaudal vertebrae and intestinal valve turns, saddles on the back without black borders and yellowish and variously shaped blotches, not forming white O-shaped spots.

Large predatory fishes, such as sharks, play an important functional role within marine ecosystems. Restocking of depleted populations has been extensively studied for commercially or recreationally important teleost fish species; however, it has, to the best of our knowledge, never been successfully attempted and assessed on sharks. We evaluated whether fifteen captive-bred wobbegongs (Orectolobus maculatus) released into a small bay inhabited by wild sharks would survive and remain within a small ‘no-take’ marine reserve. The captive-bred sharks and twelve wild sharks were tagged with acoustic transmitters and their presence was monitored by an array of acoustic receivers. The detection rate of control tags was modelled against environmental variables to predict detection probabilities and account for days when environmental conditions hampered shark detections. The overall detection probability ranged from 28% to 38% and was most affected by wind direction. Wild wobbegongs showed clear seasonal patterns of attendance to the study site, with the highest probability of presence during the summer months. The captive-bred sharks did not display the same seasonal trend in occurrence. The age at which captive-bred sharks were released into the area affected residency periods. Four out of five adults remained in the area for up to three years post release, while all the juveniles permanently left the area within a year post-release. Three of the juveniles were detected on receivers up to 12 km from the study site. Therefore, if restocking of depleted populations of sharks is to be used as a conservation strategy, the age at which sharks are released must be considered.

Information about spatial and temporal variability in the distribution and abundance of shark-populations are required for their conservation, management and to update measures designed to mitigate human-shark interactions. However, because some species of sharks are mobile, migratory and occur in relatively small numbers, estimating their patterns of distribution and abundance can be very difficult. In this study, we used a hierarchical sampling design to examine differences in the composition of species, size- and sex-structures of sharks sampled with bottom-set longlines in three different areas with increasing distance from the entrance of Sydney Harbour, a large urbanised estuary. During two years of sampling, we obtained data for four species of sharks (Port Jackson, Heterodontus portusjacksoni; wobbegong, Orectolobus maculatus; dusky whaler, Carcharhinus obscurus and bull shark, Carcharhinus leucas). Only a few O. maculatus and C. obscurus were caught, all in the area closest to the entrance of the Harbour. O. maculatus were caught in all seasons, except summer, while C. obscurus was only caught in summer. Heterodontus portusjacksoni were the most abundant species, caught in the entrance location mostly between July to November, when water temperature was below 21.5°C. This pattern was consistent across both years. C. leucas, the second most abundant species, were captured in all areas of Sydney Harbour but only in summer and autumn when water temperatures were above 23°C. This study quantified, for this first time, how different species utilise different areas of Sydney Harbour, at different times of the year. This information has implications for the management of human-shark interactions, by enabling creation of education programs to modify human behaviour in times of increased risk of potentially dangerous sharks.

DNA barcoding – sequencing a region of the mitochondrial cytochrome c oxidase 1 gene (cox1) – promises a rapid and accurate means of species identification, and of any life history stage. For sharks and rays, it may offer a ready means of identifying legal or illegal shark catches, including shark fins taken for the profitable shark fin market. Here it is shown that an analysis of sequence variability in a 655 bp region of cox1 from 945 specimens of 210 chondrichthyan species from 36 families permits the discrimination of 99.0% of these species. Only the two stingarees Urolophus sufflavus and U. cruciatus could not be separated, although these could be readily distinguished from eight other congeners. The average Kimura 2 parameter distance separating individuals within species was 0.37%, and the average distance separating species within genera was 7.48%. Two specimens that clustered with congeners rather than with their identified species-cluster were noted: these could represent instances of hybridisation (although this has not be documented for chondrichthyans), misidentification or mislabelling. It is concluded that cox1 barcoding can be used to identify shark and ray species with a very high degree of accuracy. The sequence variability characteristics of individuals of five species (Aetomylaeus nichofii, Dasyatis kuhlii, Dasyatis leylandi, Himantura gerrardi and Orectolobus maculatus) were consistent with cryptic speciation, and it is suggested that these five taxa be subjected to detailed taxonomic examination to confirm or refute this suggestion. The present barcoding study holds out great hope for the ready identification of sharks, shark products and shark fins, and also highlights some taxonomic issues that need to be investigated further.

Orectolobus hutchinsi n. sp.. is a moderate-sized wobbegong shark found in shallow continental shelf habitats off Western Australia. It occurs from Coral Bay (near North West Cape) south to Groper Bluff (west of Bremer Bay) in depths of 9–106 m where it is caught as by-catch of local gillnet, longline, rock lobster and recreational fisheries. It is sympatric with two other commercial wobbegong species, Orectolobus maculatus and O. ornatus, but differs from these and other IndoPacific species in having the combination of a few unbranched dermal lobes, relatively tall dorsal fins, no warty tubercles on the back of adults, and dark brown corrugated saddles without white spots and blotches. Some details of its biology are also provided.

A description is given of the external features of the scolex and strobila and the anatomy of the proglottid of Acanthobothrium pearsoni sp.nov. found in the intestine of Orectolobus maculatus Bon. In view of the similarity in host distribution and anatomy to that of Biporophyllaeus madrassensis Subramanian some comments are made on the status of the order Biporophyllaeidea and it is suggested that B. madrassensis may be a proglottid of a species of Acanthobothrium.

Rhinebothrium pearsoni, sp nov., is described from Banks' shovelnosed ray, Aptychotrema banksii (Muller & Henle). PhyNobothrium orectolobi, sp. nov., is described from the wobbegong, Orectolobus maculatus (Bonnaterre). Anthobothrium amuleturn, sp nov., is described from the common shovel- nosed ray, Rhinobatos armatus (Gray). Pedibothrium ottleyi, sp. nov., is described from the zebra shark, Stegostoma tigrinum (Pennant), and the genus Pedibothrium Linton, 1909, is emended. Calliobothrium creeveyae, sp. nov., is described from the school shark, Galeorhinus australis (Macleay). Polypocephalus moretonensis, sp nov., is described from the estuary stingray, Dasyatis fluviorum Ogilby. Tylocephalum carnpanulatum, sp. nov., is described from the shark ray, Rhina ancylostomus Bloch & Schneider. Also described are a species of Balanobothrium Hornell, 1912, from S. tigrinum; a species of Cathetocephalus Dailey & Overstreet, 1973, and a species of Discocephalum Linton, 1890, from the black-tip shark, Carcharhinus spallanzani (Le Sueur), and Hornellobothrium cobraformis Shipley & Hornell, 1906, from the spotted eagle-ray, Aetobatis narinari (Euphrasen).