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SMART Drumlines Ineffective in Catching White Sharks in the High Energy Capes Region of Western Australia: Acoustic Detections Confirm That Sharks Are Not Always Amenable to Capture. BIOLOGY 2022; 11:biology11101537. [PMID: 36290440 PMCID: PMC9598327 DOI: 10.3390/biology11101537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/11/2022] [Accepted: 10/14/2022] [Indexed: 11/17/2022]
Abstract
The management of human-shark interactions can benefit from the implementation of effective shark hazard mitigation measures. A Shark-Management-Alert-in-Real-Time (SMART) drumline trial in the Capes region of Western Australia was instigated after several serious incidents involving surfers and white sharks (Carcharodon carcharias). The project aimed to determine whether white sharks (target species), which were relocated after capture, remained offshore using satellite and acoustic tagging. Over a 27-month period, 352 fish were caught, 55% of which comprised tiger sharks (Galeocerdo cuvier). Ninety-one percent of animals were released alive in good condition. Only two white sharks were caught; both were relocated ≥ 1 km offshore before release and moved immediately further offshore after capture, remaining predominately in offshore waters for the duration of their 54-day and 186-day tag deployments. Our results confirm that desirable animal welfare outcomes can be achieved using SMART drumlines when response times are minimised. The low target catches and the detection of 24 other tagged white sharks within the study area supported the decision to cease the trial. Our results reiterate there is no simple remedy for dealing with the complexities of shark hazards and reinforce the importance of trialing mitigation measures under local conditions.
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Coxon JL, Butcher PA, Spaet JLY, Rizzari JR. Preliminary Data about Habitat Use of Subadult and Adult White Sharks ( Carcharodon carcharias) in Eastern Australian Waters. BIOLOGY 2022; 11:1443. [PMID: 36290347 PMCID: PMC9598950 DOI: 10.3390/biology11101443] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/19/2022] [Accepted: 09/29/2022] [Indexed: 12/24/2022]
Abstract
In eastern Australia, white sharks (Carcharodon carcharias) are targeted in shark control programs, yet the movement of subadults and adults of the eastern Australasian population is poorly understood. To investigate horizontal and vertical movement and habitat use in this region, MiniPAT pop-up satellite archival tags were deployed on three larger white sharks (340−388 cm total length) between May 2021 and January 2022. All sharks moved away from the coast after release and displayed a preference for offshore habitats. The upper < 50 m of the water column and temperatures between 14−19 °C were favoured, with a diel pattern of vertical habitat use evident as deeper depths were occupied during the day and shallower depths at night. Horizontal movement consisted of north−south seasonality interspersed with periods of residency. Very little information is available for adult white sharks in eastern Australia and studies like this provide key baseline information for their life history. Importantly, the latitudinal range achieved by white sharks illuminate the necessity for multijurisdictional management to effectively mitigate human-shark interactions whilst supporting conservation efforts of the species.
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Affiliation(s)
- Jessica L Coxon
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC 3216, Australia
| | - Paul A Butcher
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC 3216, Australia
- New South Wales Department of Primary Industries, Fisheries, National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW 2450, Australia
| | - Julia L Y Spaet
- Evolutionary Ecology Group, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Justin R Rizzari
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC 3216, Australia
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Le Croizier G, Sonke JE, Lorrain A, Renedo M, Hoyos-Padilla M, Santana-Morales O, Meyer L, Huveneers C, Butcher P, Amezcua-Martinez F, Point D. Foraging plasticity diversifies mercury exposure sources and bioaccumulation patterns in the world's largest predatory fish. JOURNAL OF HAZARDOUS MATERIALS 2022; 425:127956. [PMID: 34986563 DOI: 10.1016/j.jhazmat.2021.127956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/16/2021] [Accepted: 11/28/2021] [Indexed: 05/04/2023]
Abstract
Large marine predators exhibit high concentrations of mercury (Hg) as neurotoxic methylmercury, and the potential impacts of global change on Hg contamination in these species remain highly debated. Current contaminant model predictions do not account for intraspecific variability in Hg exposure and may fail to reflect the diversity of future Hg levels among conspecific populations or individuals, especially for top predators displaying a wide range of ecological traits. Here, we used Hg isotopic compositions to show that Hg exposure sources varied significantly between and within three populations of white sharks (Carcharodon carcharias) with contrasting ecology: the north-eastern Pacific, eastern Australasian, and south-western Australasian populations. Through Δ200Hg signatures in shark tissues, we found that atmospheric Hg deposition pathways to the marine environment differed between coastal and offshore habitats. Discrepancies in δ202Hg and Δ199Hg signatures among white sharks provided evidence for intraspecific exposure to distinct sources of marine methylmercury, attributed to population and ontogenetic shifts in foraging habitat and prey composition. We finally observed a strong divergence in Hg accumulation rates between populations, leading to three times higher Hg concentrations in large Australasian sharks compared to north-eastern Pacific sharks, and likely due to different trophic strategies adopted by adult sharks across populations. This study illustrates the variety of Hg exposure sources and bioaccumulation patterns that can be found within a single species and suggests that intraspecific variability needs to be considered when assessing future trajectories of Hg levels in marine predators.
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Affiliation(s)
- Gaël Le Croizier
- UMR Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées (OMP), 14 avenue Edouard Belin, 31400 Toulouse, France; Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Av. Joel Montes Camarena S/N, Mazatlán, Sin 82040, Mexico.
| | - Jeroen E Sonke
- UMR Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées (OMP), 14 avenue Edouard Belin, 31400 Toulouse, France
| | - Anne Lorrain
- Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzané, France
| | - Marina Renedo
- UMR Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées (OMP), 14 avenue Edouard Belin, 31400 Toulouse, France
| | - Mauricio Hoyos-Padilla
- Pelagios-Kakunjá A.C, Sinaloa 1540, Col. Las Garzas, C.P. 23070 La Paz, B.C.S., Mexico; Fins Attached: Marine Research and Conservation, 19675 Still Glen Drive, Colorado Springs, CO 80908, USA
| | | | - Lauren Meyer
- Southern Shark Ecology Group, College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia; Georgia Aquarium, Atlanta, GA 30313, USA
| | - Charlie Huveneers
- Southern Shark Ecology Group, College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
| | - Paul Butcher
- NSW Department of Primary Industries, National Marine Science Centre, Coffs Harbour, NSW 2450, Australia
| | - Felipe Amezcua-Martinez
- Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Av. Joel Montes Camarena S/N, Mazatlán, Sin 82040, Mexico
| | - David Point
- UMR Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées (OMP), 14 avenue Edouard Belin, 31400 Toulouse, France
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Davenport D, Butcher P, Andreotti S, Matthee C, Jones A, Ovenden J. Effective number of white shark ( Carcharodon carcharias, Linnaeus) breeders is stable over four successive years in the population adjacent to eastern Australia and New Zealand. Ecol Evol 2021; 11:186-198. [PMID: 33437422 PMCID: PMC7790646 DOI: 10.1002/ece3.7007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 11/08/2022] Open
Abstract
Population size is a central parameter for conservation; however, monitoring abundance is often problematic for threatened marine species. Despite substantial investment in research, many marine species remain data-poor presenting barriers to the evaluation of conservation management outcomes and the modeling of future solutions. Such is the case for the white shark (Carcharodon carcharias), a highly mobile apex predator for whom recent and substantial population declines have been recorded in many globally distributed populations. Here, we estimate the effective number of breeders that successfully contribute offspring in one reproductive cycle (Nb) to provide a snapshot of recent reproductive effort in an east Australian-New Zealand population of white shark. Nb was estimated over four consecutive age cohorts (2010, 2011, 2012, and 2013) using two genetic estimators (linkage disequilibrium; LD and sibship assignment; SA) based on genetic data derived from two types of genetic markers (single nucleotide polymorphisms; SNPs and microsatellite loci). While estimates of Nb using different marker types produced comparable estimates, microsatellite loci were the least precise. The LD and SA estimates of Nb within cohorts using SNPs were comparable; for example, the 2013 age cohort Nb(SA) was 289 (95% CI 200-461) and Nb(LD) was 208.5 (95% CI 116.4-712.7). We show that over the time period studied, Nb was stable and ranged between 206.1 (SD ± 45.9) and 252.0 (SD ± 46.7) per year using a combined estimate of Nb(LD+SA) from SNP loci. In addition, a simulation approach showed that in this population the effective population size (Ne) per generation can be expected to be larger than Nb per reproductive cycle. This study demonstrates how breeding population size can be monitored over time to provide insight into the effectiveness of recovery and conservation measures for the white shark, where the methods described here may be applicable to other data-poor species of conservation concern.
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Affiliation(s)
- Danielle Davenport
- Molecular Fisheries Laboratory and Schools of Biomedical SciencesUniversity of QueenslandSt. LuciaQLDAustralia
| | - Paul Butcher
- New South Wales Department of Primary IndustriesCoffs HarbourNSWAustralia
| | - Sara Andreotti
- Evolutionary Genomics GroupDepartment of Botany and ZoologyStellenbosch UniversityStellenboschSouth Africa
| | - Conrad Matthee
- Evolutionary Genomics GroupDepartment of Botany and ZoologyStellenbosch UniversityStellenboschSouth Africa
| | - Andrew Jones
- Molecular Fisheries Laboratory and Schools of Biomedical SciencesUniversity of QueenslandSt. LuciaQLDAustralia
| | - Jennifer Ovenden
- Molecular Fisheries Laboratory and Schools of Biomedical SciencesUniversity of QueenslandSt. LuciaQLDAustralia
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Gallagher AJ, Meyer L, Pethybridge HR, Huveneers C, Butcher PA. Effects of short-term capture on the physiology of white sharks Carcharodon carcharias: amino acids and fatty acids. ENDANGER SPECIES RES 2019. [DOI: 10.3354/esr00997] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Madliger CL. 'SMART' shark capture technology may keep beachgoers and sharks safe. CONSERVATION PHYSIOLOGY 2019; 7:coz087. [PMID: 31824673 PMCID: PMC6892462 DOI: 10.1093/conphys/coz087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 06/10/2023]
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