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Whale shark

Yingchao Zhang, Weijiang Meng, Bing Fan, Wenhui Tang
BACKGROUND: In this paper, we used the principle of biomimetics to design two-dimensional and three-dimensional bar sections, and used computational fluid dynamics software to numerically simulate and analyse the aerodynamic noise, to reduce drag and noise. METHODS: We used the principle of biomimetics to design the cross-section of a bar. An owl wing shape was used for the initial design of the section geometry; then the feathered form of an owl wing, the v-shaped micro-grooves of a shark's skin, the tubercles of a humpback whale's flipper, and the stripy surface of a scallop's shell were used to inspire surface features, added to the initial section and three-dimensional shape...
2016: SpringerPlus
Kyong Park, Eunmin Seo
BACKGROUND: Although Asian populations consume relatively large amounts of fish and seafood and have a high prevalence of metabolic diseases, few studies have investigated the association between chronic mercury exposure and metabolic syndrome and its effect modification by selenium. METHODS: We analyzed baseline data from the Trace Element Study of Korean Adults in the Yeungnam area. Participants included 232 men and 269 women, aged 35 years or older, who had complete data regarding demographic, lifestyle, diet, toenail mercury and selenium levels, and health...
2016: Nutrients
J E M Cochran, R S Hardenstine, C D Braun, G B Skomal, S R Thorrold, K Xu, M G Genton, M L Berumen
The presence of whale sharks Rhincodon typus were recorded around Shib Habil, a small, coastal reef off the Red Sea coast of Saudi Arabia, from 2010 to 2015. A total of 267 suitable photographs resulting in the identification of 136 individuals, were documented from 305 encounters. Sharks were divided evenly between the sexes with no evidence of temporal or spatial segregation. All individuals were immature based on size estimates and, for males, juvenile clasper morphology. Scars were reported for 57% of R...
September 2016: Journal of Fish Biology
David P Robinson, Mohammed Y Jaidah, Steffen Bach, Katie Lee, Rima W Jabado, Christoph A Rohner, Abi March, Simone Caprodossi, Aaron C Henderson, James M Mair, Rupert Ormond, Simon J Pierce
Data on the occurrence of whale sharks, Rhincodon typus, in the Arabian Gulf and Gulf of Oman were collected by dedicated boat surveys and via a public-sightings scheme during the period from 2011 to 2014. A total of 422 individual whale sharks were photo-identified from the Arabian Gulf and the northern Gulf of Oman during that period. The majority of sharks (81%, n = 341) were encountered at the Al Shaheen area of Qatar, 90 km off the coast, with the Musandam region of Oman a secondary area of interest. At Al Shaheen, there were significantly more male sharks (n = 171) than females (n = 78; X2 = 17...
2016: PloS One
Victoria Louise Georgia Todd, Jane Clare Warley, Ian Boyer Todd
A decade of visual and acoustic detections of marine megafauna around offshore Oil & Gas (O&G) installations in the North and Irish Seas are presented. Marine megafauna activity was monitored visually and acoustically by Joint Nature Conservation Committee (JNCC) qualified and experienced Marine Mammal Observers (MMO) and Passive Acoustic Monitoring (PAM) Operators respectively, with real-time towed PAM in combination with industry standard software, PAMGuard. Monitoring was performed during routine O&G industrial operations for underwater noise mitigation purposes, and to ensure adherence to regulatory guidelines...
2016: PloS One
Ana M M Sequeira, Michele Thums, Kim Brooks, Mark G Meekan
Body size and age at maturity are indicative of the vulnerability of a species to extinction. However, they are both difficult to estimate for large animals that cannot be restrained for measurement. For very large species such as whale sharks, body size is commonly estimated visually, potentially resulting in the addition of errors and bias. Here, we investigate the errors and bias associated with total lengths of whale sharks estimated visually by comparing them with measurements collected using a stereo-video camera system at Ningaloo Reef, Western Australia...
March 2016: Royal Society Open Science
Peter B Best, Theoni Photopoulou
The presence of crater-like wounds on cetaceans and other large marine vertebrates and invertebrates has been attributed to various organisms. We review the evidence for the identity of the biting agent responsible for crater wounds on large whales, using data collected from sei (Balaenoptera borealis), fin (B. physalus), inshore and offshore Bryde's (B. brydeii sp) and sperm whales (Physeter macrocephalus) examined at the Donkergat whaling station, Saldanha Bay, South Africa between March and October 1963...
2016: PloS One
S Laurie Sanderson, Erin Roberts, Jillian Lineburg, Hannah Brooks
Suspension-feeding fishes such as goldfish and whale sharks retain prey without clogging their oral filters, whereas clogging is a major expense in industrial crossflow filtration of beer, dairy foods and biotechnology products. Fishes' abilities to retain particles that are smaller than the pore size of the gill-raker filter, including extraction of particles despite large holes in the filter, also remain unexplained. Here we show that unexplored combinations of engineering structures (backward-facing steps forming d-type ribs on the porous surface of a cone) cause fluid dynamic phenomena distinct from current biological and industrial filter operations...
2016: Nature Communications
Hungyen Chen, Hirohisa Kishino
The diversity of marine communities is in striking contrast with the diversity of terrestrial communities. In all oceans, species richness is low in tropical areas and high at latitudes between 20 and 40°. While species richness is a primary metric used in conservation and management strategies, it is important to take into account the complex phylogenetic patterns of species compositions within communities. We measured the phylogenetic skew and diversity of shark communities throughout the world. We found that shark communities in tropical seas were highly phylogenetically skewed, whereas temperate sea communities had phylogenetically diversified species compositions...
October 2015: Ecology and Evolution
Kunlin Chen, Shuxue Zhou, Limin Wu
Marine biofouling has been plaguing people for thousands of years. While various strategies have been developed for antifouling (including superoleophobic) coatings, none of these exhibits self-healing properties because the bestowal of a zoetic self-repairing function to lifeless artificial water/solid interfacial materials is usually confronted with tremendous challenges. Here, we present a self-repairing underwater superoleophobic and antibiofouling coating through the self-assembly of hydrophilic polymeric chain modified hierarchical microgel spheres...
January 26, 2016: ACS Nano
Anna Schleimer, Gonzalo Araujo, Luke Penketh, Anna Heath, Emer McCoy, Jessica Labaja, Anna Lucey, Alessandro Ponzo
While shark-based tourism is a rapidly growing global industry, there is ongoing controversy about the effects of provisioning on the target species. This study investigated the effect of feeding on whale sharks (Rhincodon typus) at a provisioning site in Oslob, Cebu, in terms of arrival time, avoidance and feeding behaviour using photo-identification and focal follows. Additionally, compliance to the code of conduct in place was monitored to assess tourism pressure on the whale sharks. Newly identified sharks gradually arrived earlier to the provisioning site after their initial sighting, indicating that the animals learn to associate the site with food rewards...
2015: PeerJ
C A Radford, J C Montgomery
The top predators in coastal marine ecosystems, such as whales, dolphins, seabirds, and large predatory fishes (including sharks), may compete with each other to exploit food aggregations. Finding these patchy food sources and being first to a food patch could provide a significant competitive advantage. Our hypothesis is that food patches have specific sound signatures that marine predators could detect and that acoustic sources and animal sensory capabilities may contribute to competition dynamics. Preliminary analysis shows that diving gannets have a distinct spectral signature between 80 and 200 Hz, which falls within the hearing sensitivity of large pelagic fishes...
2016: Advances in Experimental Medicine and Biology
Ryo Nozu, Kiyomi Murakumo, Rui Matsumoto, Masaru Nakamura, Keiichi Ueda, Keiichi Sato
Captive breeding of whale sharks is one of the great challenges for aquariums. However, there is limited information available related to reproductive physiology due to the difficulty of sampling and long-term observation. In the present report, we provide information on the reproductive physiology of female whale sharks, which were incidentally captured as bycatch in a set-net off the coast of Okinawa, Japan. Total lengths of three captured female whale sharks were 403, 665, and 761 cm, respectively, at the time of their death...
October 2015: Zoological Science
Melissa A McKinney, Kylie Dean, Nigel E Hussey, Geremy Cliff, Sabine P Wintner, Sheldon F J Dudley, M Philip Zungu, Aaron T Fisk
Conservation concern regarding the overharvest of global shark populations for meat and fin consumption largely surrounds documented deleterious ecosystem effects, but may be further supported by improved knowledge of possibly high levels in their edible tissues (particularly meat) of the neurotoxin, methylmercury (CH3Hg). For many regions, however, little data exist on shark tissue Hg concentrations, and reasons for Hg variation within and among species or across regions are poorly understood. We quantified total Hg (THg) in 17 shark species (total n=283) from the east coast of South Africa, a top Hg emitter globally...
January 15, 2016: Science of the Total Environment
Christoph A Rohner, Anthony J Richardson, Clare E M Prebble, Andrea D Marshall, Michael B Bennett, Scarla J Weeks, Geremy Cliff, Sabine P Wintner, Simon J Pierce
Whale sharks Rhincodon typus are globally threatened, but a lack of biological and demographic information hampers an accurate assessment of their vulnerability to further decline or capacity to recover. We used laser photogrammetry at two aggregation sites to obtain more accurate size estimates of free-swimming whale sharks compared to visual estimates, allowing improved estimates of biological parameters. Individual whale sharks ranged from 432-917 cm total length (TL) (mean ± SD = 673 ± 118.8 cm, N = 122) in southern Mozambique and from 420-990 cm TL (mean ± SD = 641 ± 133 cm, N = 46) in Tanzania...
2015: PeerJ
E Fernando Cagua, Jesse E M Cochran, Christoph A Rohner, Clare E M Prebble, Tane H Sinclair-Taylor, Simon J Pierce, Michael L Berumen
Although whale sharks (Rhincodon typus) have been documented to move thousands of kilometres, they are most frequently observed at a few predictable seasonal aggregation sites. The absence of sharks at the surface during visual surveys has led to the assumption that sharks disperse to places unknown during the long 'off-seasons' at most of these locations. Here we compare 2 years of R. typus visual sighting records from Mafia Island in Tanzania to concurrent acoustic telemetry of tagged individuals. Sightings revealed a clear seasonal pattern with a peak between October and February and no sharks observed at other times...
April 2015: Biology Letters
Christoph A Rohner, Amelia J Armstrong, Simon J Pierce, Clare E M Prebble, E Fernando Cagua, Jesse E M Cochran, Michael L Berumen, Anthony J Richardson
Large planktivores require high-density prey patches to make feeding energetically viable. This is a major challenge for species living in tropical and subtropical seas, such as whale sharks Rhincodon typus. Here, we characterize zooplankton biomass, size structure and taxonomic composition from whale shark feeding events and background samples at Mafia Island, Tanzania. The majority of whale sharks were feeding (73%, 380 of 524 observations), with the most common behaviour being active surface feeding (87%)...
March 2015: Journal of Plankton Research
Easton R White, Mark C Myers, Joanna Mills Flemming, Julia K Baum
Fishing pressure has increased the extinction risk of many elasmobranch (shark and ray) species. Although many countries have established no-take marine reserves, a paucity of monitoring data means it is still unclear if reserves are effectively protecting these species. We examined data collected by a small group of divers over the past 21 years at one of the world's oldest marine protected areas (MPAs), Cocos Island National Park, Costa Rica. We used mixed effects models to determine trends in relative abundance, or probability of occurrence, of 12 monitored elasmobranch species while accounting for variation among observers and from abiotic factors...
August 2015: Conservation Biology: the Journal of the Society for Conservation Biology
Alistair D M Dove
Whale sharks, Rhincodon typus, display a number of behaviors that suggest these animals can locate food from afar, as well as identify and discriminate between food items. However, their intractably large size and relative rarity in the field has so far prevented direct studies of their behavior and sensory capability. A small population of aquarium-held whale sharks facilitated direct studies of behavior in response to chemical stimulus plumes. Whale sharks were exposed to plumes composed of either homogenized krill or simple aqueous solutions of dimethyl sulfide (DMS), which is associated with krill aggregations and is used by several pelagic species as a food-finding stimulus...
February 2015: Biological Bulletin
Justin Marshall, Karen L Carleton, Thomas Cronin
Colour vision in the marine environment is on average simpler than in terrestrial environments with simple or no colour vision through monochromacy or dichromacy. Monochromacy is found in marine mammals and elasmobranchs, including whales and sharks, but not some rays. Conversely, there is also a greater diversity of colour vision in the ocean than on land, examples being the polyspectral stomatopods and the many colour vision solutions found among reef fish. Recent advances in sequencing reveal more opsin (visual pigment) types than functionally useful at any one time...
October 2015: Current Opinion in Neurobiology
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