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Understanding movement patterns underlies effective management and conservation measures. The current study summarises the main findings from a tagging program of Western Australian sharks to provide insights into the movement patterns of the main commercial shark species: dusky (Carcharhinus obscurus), sandbar (C. plumbeus), gummy (Mustelus antarcticus) and whiskery (Furgaleus macki) sharks. Between 1993 and 2020, >12 000 individuals from 52 taxonomic groups were implanted with conventional tags in Western Australia, of which 8.5% were recaptured. Most of the tagged (74.5%) and recaptured (95.8%) individuals belong to the four main commercial shark species. Recaptured individuals of these species, as well as tiger (Galeocerdo cuvier) and bronze whaler (C. brachyurus) sharks showed displacements of >1000 km and rates of movement (ROMs) of >10 km day–1, with the exception of whiskery sharks, which showed much slower ROMs (

Understanding the movement ecology of marine species and connectivity of populations is required for effective fisheries management. This is especially the case for species with wide-ranging distributions for which movement can span across several jurisdictions with different management regulations. We used the Australian national network of acoustic receivers facilitated by the Integrated Marine Observing System (IMOS) to describe the extent and frequency of movements for two large epipelagic shark species, the bronze whaler (Carcharhinus brachyurus) and dusky shark (Carcharhinus obscurus). A total of 210 sharks (117 bronze whalers and 93 dusky sharks) were tracked for a 10-year period during which 21% and 9% of detected bronze whalers and dusky sharks, respectively, moved between Australian states. Bronze whalers showed more variable inter-state movements, mostly between Western Australia and South Australia but also eastwards to New South Wales (NSW). Although no dusky sharks tagged in Western Australia undertook inter-state movements, ∼50% of the sharks tagged in South Australia went to Western Australia. Five of the 14 dusky sharks tagged in NSW (36%) were detected across different states but remained on the east and southeast coasts (Queensland, NSW, Victoria, and Tasmania). The IMOS receivers also detected six bronze whalers in Ningaloo Reef, representing an extension of the previously known Australian distribution. Our findings highlight the value of collaboration between researchers and the value of national infrastructure, by providing a more accurate understanding of inter-state movements. This new information will allow the development of more adequate population dynamic models for stock assessment and management advice, requiring collaboration among state agencies for coordinating research activities, sharing data and resources, and establishing appropriate cross-jurisdictional policies. This is essential to achieve successful management and conservation outcomes for highly migratory species.

Assessing the movements and habitat use of wide-ranging predators is critical for understanding their role within an ecosystem and vulnerability to anthropogenic threats. The bronze whaler (Carcharhinus brachyurus) is a large-bodied, slow-growing shark species that is widely distributed throughout temperate Australian waters. Currently, habitat use, spatio-temporal presence and fine-scale movement information is unknown for Southern Australian waters. This study investigated the spatio-temporal patterns of occurrence, habitat use, and residency of bronze whalers in Gulf St. Vincent, South Australia. Forty-seven predominately small juvenile bronze whalers (83% of tagged sharks

Sharks and their relatives (Chondrichthyes) were an important food source for pre-European Māori. However, their skeletons, which are largely comprised of cartilage, are poorly preserved in the archaeological record, with only teeth and vertebrae routinely recorded. Furthermore, it is often difficult to identify Chondrichthyes by their vertebral morphology. Here we compare the morphological and ancient DNA identification of 180 Chondrichthyes vertebrae representing seven different morphotypes sampled from a large archaeological assemblage in Auckland, New Zealand. aDNA sequences were obtained from 87 vertebrae and indicated the presence of four Chondrichthyes species at the site: rig (Mustelus lenticulatus), school shark (Galeorhinus galeus), bronze whaler (Carcharhinus brachyurus) and New Zealand eagle ray (Myliobatis tenuicaudatus). The aDNA results indicated several instances where morphological identification of vertebrae had been incorrect, including the most common taxon found in the assemblage, rig, which had been identified morphologically as school shark. Overall, our results indicated that aDNA analysis of Chondrichthyes vertebrae is a valuable tool to distinguish between specimens with morphologically similar vertebrae and to verify morphological identifications.

The low incidence of reported tumours in elasmobranchs has led to the assumption that the group rarely develops cancerous diseases (Loprinzi et al. 2005). This, combined with some studies reporting a therapeutic benefit in cartilage extract (e.g. Cho & Kim 2002), has resulted in a worldwide demand for shark cartilage products for use as alternative therapies (Berzins & Hovland 1999). This demand has, at least in part, increased the pressure on shark populations contributing to their worldwide decline (Ostrander et al. 2004). While reported cases are relatively low, both benign and cancerous proliferative lesions have been reported in 21 species of sharks from over 9 families (Ostrander et al. 2004; National Cancer Institute 2007). Cutaneous neoplasms have been reported in a number of elasmobranchs including the tiger shark, Galeocerdo cuvier (M€ uller and Henle) (Ostrander et al. 2004), the smooth dogfish, Mustelus canis Mitchill (Wolke & Murchelano 1976), and the bull shark, Carcharhinus leucas M€ uller and Henle (Harshbarger 1972). Odontogenic, oral and gingival neoplasms are well documented in bony fish (Harshbarger & Clark 1990; Grizzle & Goodwin 1998) and were reported from sharks including the grey nurse shark, Carcharias taurus Rafinesque, and blue shark, Prionace glauca L. (Borucinska et al. 2004). Various studies and observations suggest a relationship between tumour development and environmental contamination in other species (McAloose & Newton 2009). Rates of reported neoplasm in marine mammals have steadily increased over the past two decades including newly described and resurging diseases, giving rise to concern whether such tumours could be reflective of environmental distress syndrome triggered by human-related activities (Bossart 2007). This study describes the first observations of proliferative, possibly neoplastic, lesions in two elasmobranch species: a great white shark, Carcharodon carcharias L., and a bronze whaler, Carcharhinus brachyurus G€ unther observed at the Neptune Islands in South Australia. Photographic images of white sharks at the Neptune Islands, South Australia, were obtained by still cameras or through the use of a camera mounted on a handheld pole, as part of an ongoing photographic identification database program. Each photograph was categorized based on the sex of the shark; approximate size; pigment patterns from the gill, dorsal, ventral fin and caudal fin regions; and permanent markings such as major scars; notches on the dorsal fin; and amputations or mutilations. In addition to its use for identification, the database is also used to document incidences of white shark injuries and to record resighting rates of sharks from year to year. Correspondence R Robbins, Fox Shark Research Foundation, 73 Ninth Avenue, Joslin, SA 5070, Australia (e-mail: rachel@sharkfoundation.com)

Intra-species plasticity in the life-history characteristics of sharks leads to the need for regional estimates to accurately determine resilience to anthropogenic effects. The present study provides the first length-at-age, growth and maturity estimates for the bronze whaler (Carcharhinus brachyurus) from southern Australia. Age estimates were obtained from vertebral sections of 466 individuals spanning 50–308-cm total length. Maximum estimates of age for males and females were 25 and 31 years respectively. The three-parameter logistic model for females (L∞=308cm LT, k=0.15, α=742) and for males (L∞=317cm LT, k=0.13, α=782) provided the best fit to the size at age data. Males matured at a similar age (16 years), but smaller size than females (224v. 270cm LT). Growth parameters and age-at-maturity estimates were similar to those for genetically isolated C. brachyurus populations, and the sympatric dusky shark (C. obscurus). The southern Australian C. brachyurus population is long-lived, slow growing and late maturing. These growth parameters are needed to undertake demographic analyses to assess the resilience of C. brachyurus to fishing, and provide an example of a wide-ranging elasmobranch with similar life-history characteristics across isolated populations.

Counts of growth bands in sectioned vertebral centra were used to estimate the ages of 61 bronze whalers Carcharhinus brachyurus collected between March 1984 and June 1988 from southern Africa. Estimates of Von Bertalanffy parameters for the observed data were: L ∞ = 384,8, K = 0,0385, t 0 = −3,477. The t0 value overestimates the gestation, which is thought to be between 8 and 24 months. Growth in bronze whalers appears to be slower than in any Carcharhinus spp. previously studied. Maximum size recorded during this study was 294 cm total length (TL) for a male and 288 cm TL for a female, and the maximum ages recorded were 30 and 25 years respectively. Age at sexual maturity has been calculated at 13–19 years for males and 19–20 years for females. Differential mortality rates appear to operate on juveniles (Lee's phenomenon). Arguments are presented that indicate two separate populations: one distributed from the Western Cape eastwards and the other from just south of Walvis Bay northwards. The slow growth...

During hydroacoustic observations in November 2002, a large concentration of chokka squid (Loligo reynaudi) was monitored for three days during fairly constant wind speed and direction, that marginally improved during the period of observations. During this period, the concentration (estimated biomass 48 t) disintegrated into small, separate aggregations. Most often, such dispersal is weather-related, but obviously not in this case. Instead, a bottom trawl made adjacent to the concentration, as well as underwater camera observations revealed an unusually large number of predators, mostly bronze whaler sharks (Carcharhinus brachyurus). Most whaler sharks caught in the trawl had chokka in their stomachs. Therefore, one explanation for the break-up of this squid concentration was the unusual predator activity. Video observations revealed, that these attacks occurred on the bottom where squid spawn; while none were observed in the water column where squid pair, mate and swim in a circular motion preparing for descent to the egg bed. The disintegration of the whole concentration suggested that disrupted spawning affects the upper part of the typical mushroom-shaped structure as well, and squid subsequently disperse and/or move away as a result of predation by whaler sharks.

International audience; The dusky shark Carcharhinus obscurus and the bronze whaler Carcharhinus brachyurus are large-bodied, marine predators that inhabit coastal and shelf waters of southern Australia. C. obscurus is considered to be among the most vulnerable pelagic sharks to overexploitation. This study focussed on population metrics and movement patterns of these sympatric species. Litters from two pregnant C. brachyurus were examined; these comprised 20 and 24 embryos, respectively. Tagging data indicated that 75% of whaler sharks tagged in this region by recreational fishers were juveniles, and 58% of recaptures occurred within 50 km of the tagging locations. Fishery catch samples comprised 99% juvenile C. brachyurus and C. obscurus. Our findings suggested that semi-protected gulf waters represented ecologically significant habitats of juveniles. A fuzzy-logic model showed that in terms of relative vulnerability to fishing, C. brachyurus ranked in the mid to lower end of the spectrum, when compared with six sympatric pelagic shark species, including the white shark, Carcharodon carcharias. Our findings emphasised a need for improvement to management measures for these carcharhinids, which are likely to play a significant role in the functioning of the temperate gulf and shelf ecosystems.

The copper or bronze whaler shark (Carcharhinus brachyurus) is a large, coastal top predator that is vulnerable to overexploitation. We test the null hypothesis that copper sharks are panmictic throughout the southern hemisphere. We analysed part of the mitochondrial control region (mtCR) in 120 individuals from eight sampling areas, defining 20 mtCR haplotypes (h = 0.76 ± 0.06, π = 0.016 ± 0.0007). Significant genetic structure was detected among the following three major coastal regions separated by oceanic habitat: Australia–New Zealand, South Africa–Namibia and Perú (AMOVA ΦST = 0.95, P