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Sanderson SL, Roberts E, Lineburg J, Brooks H. Fish mouths as engineering structures for vortical cross-step filtration. Nat Commun 2016; 7:11092. [PMID: 27023700 PMCID: PMC4820540 DOI: 10.1038/ncomms11092] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 02/17/2016] [Indexed: 11/09/2022] Open
Abstract
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. This vortical cross-step filtration model prevents clogging and explains the transport of tiny concentrated particles to the oesophagus using a hydrodynamic tongue. Mass transfer caused by vortices along d-type ribs in crossflow is applicable to filter-feeding duck beak lamellae and whale baleen plates, as well as the fluid mechanics of ventilation at fish gill filaments.
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Affiliation(s)
- S. Laurie Sanderson
- Department of Biology, College of William and Mary, PO Box 8795, Williamsburg, Virginia 23187, USA
| | - Erin Roberts
- Department of Biology, College of William and Mary, PO Box 8795, Williamsburg, Virginia 23187, USA
| | - Jillian Lineburg
- Department of Biology, College of William and Mary, PO Box 8795, Williamsburg, Virginia 23187, USA
| | - Hannah Brooks
- Department of Biology, College of William and Mary, PO Box 8795, Williamsburg, Virginia 23187, USA
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Sequeira AMM, Thums M, Brooks K, Meekan MG. Error and bias in size estimates of whale sharks: implications for understanding demography. ROYAL SOCIETY OPEN SCIENCE 2016; 3:150668. [PMID: 27069656 PMCID: PMC4821267 DOI: 10.1098/rsos.150668] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 02/18/2016] [Indexed: 05/30/2023]
Abstract
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. Using linear mixed-effects models, we found that visual lengths were biased towards underestimation with increasing size of the shark. When using the stereo-video camera, the number of larger individuals that were possibly mature (or close to maturity) that were detected increased by approximately 10%. Mean lengths calculated by each method were, however, comparable (5.002 ± 1.194 and 6.128 ± 1.609 m, s.d.), confirming that the population at Ningaloo is mostly composed of immature sharks based on published lengths at maturity. We then collated data sets of total lengths sampled from aggregations of whale sharks worldwide between 1995 and 2013. Except for locations in the East Pacific where large females have been reported, these aggregations also largely consisted of juveniles (mean lengths less than 7 m). Sightings of the largest individuals were limited and occurred mostly prior to 2006. This result highlights the urgent need to locate and quantify the numbers of mature male and female whale sharks in order to ascertain the conservation status and ensure persistence of the species.
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Affiliation(s)
- Ana M. M. Sequeira
- IOMRC and The UWA Oceans Institute, School of Animal Biology and Centre for Marine Futures, University of Western Australia (M470), 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Michele Thums
- School of Civil, Environmental and Mining Engineering and UWA Oceans Institute, University of Western Australia (M470), 35 Stirling Highway, Crawley, Western Australia 6009, Australia
- Australian Institute of Marine Science, c/o UWA Oceans Institute (MO96), 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Kim Brooks
- Australian Institute of Marine Science, c/o UWA Oceans Institute (MO96), 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Mark G. Meekan
- Australian Institute of Marine Science, c/o UWA Oceans Institute (MO96), 35 Stirling Highway, Crawley, Western Australia 6009, Australia
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Tyminski JP, de la Parra-Venegas R, González Cano J, Hueter RE. Vertical Movements and Patterns in Diving Behavior of Whale Sharks as Revealed by Pop-Up Satellite Tags in the Eastern Gulf of Mexico. PLoS One 2015; 10:e0142156. [PMID: 26580405 PMCID: PMC4651344 DOI: 10.1371/journal.pone.0142156] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/18/2015] [Indexed: 11/19/2022] Open
Abstract
The whale shark (Rhincodon typus) is a wide-ranging, filter-feeding species typically observed at or near the surface. This shark's sub-surface habits and behaviors have only begun to be revealed in recent years through the use of archival and satellite tagging technology. We attached pop-up satellite archival transmitting tags to 35 whale sharks in the southeastern Gulf of Mexico off the Yucatan Peninsula from 2003-2012 and three tags to whale sharks in the northeastern Gulf off Florida in 2010, to examine these sharks' long-term movement patterns and gain insight into the underlying factors influencing their vertical habitat selection. Archived data were received from 31 tags deployed on sharks of both sexes with total lengths of 5.5-9 m. Nine of these tags were physically recovered facilitating a detailed long-term view into the sharks' vertical movements. Whale sharks feeding inshore on fish eggs off the northeast Yucatan Peninsula demonstrated reverse diel vertical migration, with extended periods of surface swimming beginning at sunrise followed by an abrupt change in the mid-afternoon to regular vertical oscillations, a pattern that continued overnight. When in oceanic waters, sharks spent about 95% of their time within epipelagic depths (<200 m) but regularly undertook very deep ("extreme") dives (>500 m) that largely occurred during daytime or twilight hours (max. depth recorded 1,928 m), had V-shaped depth-time profiles, and comprised more rapid descents (0.68 m sec-1) than ascents (0.50 m sec-1). Nearly half of these extreme dives had descent profiles with brief but conspicuous changes in vertical direction at a mean depth of 475 m. We hypothesize these stutter steps represent foraging events within the deep scattering layer, however, the extreme dives may have additional functions. Overall, our results demonstrate complex and dynamic patterns of habitat utilization for R. typus that appear to be in response to changing biotic and abiotic conditions influencing the distribution and abundance of their prey.
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Affiliation(s)
- John P. Tyminski
- Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America
| | | | - Jaime González Cano
- Proyecto Dominó, Comisión Nacional de Áreas Naturales Protegidas, Cancún, Quintana Roo, México
| | - Robert E. Hueter
- Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America
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Laranjeira M, Guimarães J, Amorim A, Rotundo M, Rici R, Mari R. Ultrastructure of dermal denticles in sharpnose shark (Rhizoprionodon lalandii) (Elasmobranchii, Carcharhinidae). Microsc Res Tech 2015; 78:859-64. [DOI: 10.1002/jemt.22546] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/25/2015] [Accepted: 06/14/2015] [Indexed: 11/09/2022]
Affiliation(s)
- M.E. Laranjeira
- Laboratório De Morfologia De Animais Marinhos, Universidade Estadual Paulista Júlio De Mesquita Filho-Campus Do Litoral Paulista; Praça Infante Dom Henrique, S/N° 11330-900 São Vicente São Paulo Brazil
| | - J.P. Guimarães
- Laboratório De Biologia De Organismos Marinhos E Costeiros; Universidade Santa Cecília; R. Oswaldo Cruz, 266 11045-907 Santos São Paulo Brazil
| | - A.F. Amorim
- Instituto De Pesca De Santos; Rua Bartolomeu De Gusmão, 192, 11030-906 Ponta Da Praia Santos São Paulo Brazil
| | - M. Rotundo
- Acervo Zoológico Da Universidade Santa Cecília (AZUSC-UNISANTA); R. Oswaldo Cruz, 266, Brazil 11045-907 Boqueirão, Santos São Paulo Brazil
| | - R.E.G. Rici
- Faculdade De Medicina Veterinária E Zootecnia Da Universidade De São Paulo; Av. Prof.Dr. Orlando Marques De Paiva, 87, 05508270 Cidade Universitária São Paulo São Paulo Brazil
| | - R.B. Mari
- Laboratório De Morfologia De Animais Marinhos, Universidade Estadual Paulista Júlio De Mesquita Filho-Campus Do Litoral Paulista; Praça Infante Dom Henrique, S/N° 11330-900 São Vicente São Paulo Brazil
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Ferry LA, Paig-Tran EM, Gibb AC. Suction, Ram, and Biting: Deviations and Limitations to the Capture of Aquatic Prey. Integr Comp Biol 2015; 55:97-109. [PMID: 25980566 DOI: 10.1093/icb/icv028] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
When feeding, most aquatic organisms generate suction that draws prey into the mouth. The papers in this volume are a demonstration of this fact. However, under what circumstances is suction ineffective as a feeding mechanism? Here we consider the interplay between suction, ram, and biting, and analyze the contribution of each to the capture of prey by a wide variety of species of fish. We find, not surprisingly, that ram is the dominant contributor to feeding because suction, and biting, are only effective when very close to the prey. As species utilize more strongly ram-dominated modes of feeding, they may be released from the morphological and behavioral constraints associated with the need to direct a current of water into the head. Morphological and behavioral changes that facilitate larger gapes and stronger jaws are explored here, including predators that lack a protrusile upper jaw, predators with elongate jaws, predators that rely on suspension feeding, and predators that bite. Interestingly, while the mobility of the jaws and the shape of the opening of the mouth are modified in species that have departed from a primary reliance on suction feeding, the anterior-to-posterior wave of expansion persists. This wave may be greatly slowed in ram and biting species, but its retention suggests a fundamental importance to aquatic feeding.
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Affiliation(s)
- Lara A Ferry
- *School of Mathematical and Natural Sciences, Arizona State University, 4701 West Thunderbird Road, Mail Code 2352, Glendale, AZ 85069, USA; Department of Biology, California State University, Fullerton, CA 92831, USA; Department of Biology, Northern Arizona University, Flagstaff, AZ 86001, USA
| | - E Misty Paig-Tran
- *School of Mathematical and Natural Sciences, Arizona State University, 4701 West Thunderbird Road, Mail Code 2352, Glendale, AZ 85069, USA; Department of Biology, California State University, Fullerton, CA 92831, USA; Department of Biology, Northern Arizona University, Flagstaff, AZ 86001, USA
| | - Alice C Gibb
- *School of Mathematical and Natural Sciences, Arizona State University, 4701 West Thunderbird Road, Mail Code 2352, Glendale, AZ 85069, USA; Department of Biology, California State University, Fullerton, CA 92831, USA; Department of Biology, Northern Arizona University, Flagstaff, AZ 86001, USA
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Holley LL, Heidman MK, Chambers RM, Sanderson SL. Mucous contribution to gut nutrient content in American gizzard shad Dorosoma cepedianum. JOURNAL OF FISH BIOLOGY 2015; 86:1457-1470. [PMID: 25809583 DOI: 10.1111/jfb.12656] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 12/15/2014] [Indexed: 06/04/2023]
Abstract
This study developed and applied an approach to calculate the proportion of fish gut content composed of mucus secreted by the oropharyngeal cavity and gut. The amount of nitrogen in the contents of the foregut (oesophagus and gizzard) and the epibranchial organs of suspension-feeding American gizzard shad Dorosoma cepedianum was significantly higher than the nitrogen in the homogeneous food source. Using data collected from suspension-feeding experiments and the nitrogen content of D. cepedianum mucus, a series of equations illustrated that mucus constituted c. 10% of D. cepedianum foregut content and 12% of epibranchial organ content by dry mass. Future quantification of fish feeding selectivity and absorption efficiency can use this approach to take into account the contribution of fish mucus to the nutrients in the gut contents. This study supports the conclusion that suspension-feeding D. cepedianum in a heterogeneous environment selectively ingest nutrient-rich particles, even when gut nutrient content is adjusted to take into account the contribution of mucus.
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Affiliation(s)
- L L Holley
- Edge Engineering and Science, 16360 Park Ten Place, Suite 300, Houston, TX 77084, U.S.A
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57
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Rohner CA, Richardson AJ, Prebble CEM, Marshall AD, Bennett MB, Weeks SJ, Cliff G, Wintner SP, Pierce SJ. Laser photogrammetry improves size and demographic estimates for whale sharks. PeerJ 2015; 3:e886. [PMID: 25870776 PMCID: PMC4393817 DOI: 10.7717/peerj.886] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 03/19/2015] [Indexed: 11/20/2022] Open
Abstract
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. By combining measurements of stranded individuals with photogrammetry measurements of free-swimming sharks, we calculated length at 50% maturity for males in Mozambique at 916 cm TL. Repeat measurements of individual whale sharks measured over periods from 347-1,068 days yielded implausible growth rates, suggesting that the growth increment over this period was not large enough to be detected using laser photogrammetry, and that the method is best applied to estimating growth rates over longer (decadal) time periods. The sex ratio of both populations was biased towards males (74% in Mozambique, 89% in Tanzania), the majority of which were immature (98% in Mozambique, 94% in Tanzania). The population structure for these two aggregations was similar to most other documented whale shark aggregations around the world. Information on small (<400 cm) whale sharks, mature individuals, and females in this region is lacking, but necessary to inform conservation initiatives for this globally threatened species.
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Affiliation(s)
- Christoph A Rohner
- Marine Megafauna Foundation , Praia do Tofo Inhambane , Mozambique ; CSIRO Oceans and Atmosphere Flagship , Brisbane Queensland , Australia
| | - Anthony J Richardson
- CSIRO Oceans and Atmosphere Flagship , Brisbane Queensland , Australia ; Centre for Applications in Natural Resource Mathematics (CARM), School of Mathematics and Physics, The University of Queensland , St Lucia Queensland , Australia
| | | | - Andrea D Marshall
- Marine Megafauna Foundation , Praia do Tofo Inhambane , Mozambique ; Wild Me , Praia do Tofo Inhambane , Mozambique
| | - Michael B Bennett
- School of Biomedical Sciences, The University of Queensland , St Lucia Queensland , Australia
| | - Scarla J Weeks
- Biophysical Oceanography Group, School of Geography, Planning and Environmental Management, The University of Queensland , St Lucia Queensland , Australia
| | - Geremy Cliff
- KwaZulu-Natal Sharks Board , Umhlanga , South Africa ; Biomedical Resource Unit, University of KwaZulu-Natal , Durban , South Africa
| | - Sabine P Wintner
- KwaZulu-Natal Sharks Board , Umhlanga , South Africa ; Biomedical Resource Unit, University of KwaZulu-Natal , Durban , South Africa
| | - Simon J Pierce
- Marine Megafauna Foundation , Praia do Tofo Inhambane , Mozambique ; Wild Me , Praia do Tofo Inhambane , Mozambique
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58
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Rohner CA, Armstrong AJ, Pierce SJ, Prebble CEM, Cagua EF, Cochran JEM, Berumen ML, Richardson AJ. Whale sharks target dense prey patches of sergestid shrimp off Tanzania. JOURNAL OF PLANKTON RESEARCH 2015; 37:352-362. [PMID: 25814777 PMCID: PMC4371762 DOI: 10.1093/plankt/fbv010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 02/15/2015] [Indexed: 05/25/2023]
Abstract
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%). We used 20 samples collected from immediately adjacent to feeding sharks and an additional 202 background samples for comparison to show that plankton biomass was ∼10 times higher in patches where whale sharks were feeding (25 vs. 2.6 mg m-3). Taxonomic analyses of samples showed that the large sergestid Lucifer hanseni (∼10 mm) dominated while sharks were feeding, accounting for ∼50% of identified items, while copepods (<2 mm) dominated background samples. The size structure was skewed towards larger animals representative of L.hanseni in feeding samples. Thus, whale sharks at Mafia Island target patches of dense, large, zooplankton dominated by sergestids. Large planktivores, such as whale sharks, which generally inhabit warm oligotrophic waters, aggregate in areas where they can feed on dense prey to obtain sufficient energy.
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Affiliation(s)
- Christoph A. Rohner
- Marine Megafauna Foundation, Praia Do Tofo, Inhambane, Mozambique
- Oceans and Atmosphere Flagship, Csiro Marine and Atmospheric Research, Ecosciences Precinct, Dutton Park, Brisbane, QLD 4102, Australia
| | - Amelia J. Armstrong
- Oceans and Atmosphere Flagship, Csiro Marine and Atmospheric Research, Ecosciences Precinct, Dutton Park, Brisbane, QLD 4102, Australia
| | - Simon J. Pierce
- Marine Megafauna Foundation, Praia Do Tofo, Inhambane, Mozambique
- Wild Me, Tofo Beach, Inhambane, Mozambique
| | | | - E. Fernando Cagua
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Jesse E. M. Cochran
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Michael L. Berumen
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Anthony J. Richardson
- Oceans and Atmosphere Flagship, Csiro Marine and Atmospheric Research, Ecosciences Precinct, Dutton Park, Brisbane, QLD 4102, Australia
- Centre for Applications in Natural Resource Mathematics (CARM), School of Mathematics and Physics, The University of Queensland, St Lucia, QLD 4072, Australia
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Cárdenas-Palomo N, Herrera-Silveira J, Velázquez-Abunader I, Reyes O, Ordoñez U. Distribution and feeding habitat characterization of whale sharks Rhincodon typus in a protected area in the north Caribbean Sea. JOURNAL OF FISH BIOLOGY 2015; 86:668-686. [PMID: 25523625 DOI: 10.1111/jfb.12589] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/21/2014] [Indexed: 06/04/2023]
Abstract
The relationship between the distribution of the whale shark Rhincodon typus and hydrobiological variables in the Caribbean Sea during 2005-2009 was analysed. Monthly trips were made to the R. typus aggregation area during the months when this species is present in the region (May to September) to record sightings and hydrological data and to collect samples to determine nutrients, chlorophyll a (Chl a) and zooplankton biomass. A total of 2104 R. typus were counted and three zones of high abundance were identified: Cabo-Catoche, Contoy (both within the Whale Shark Biosphere Reserve, WSBR) and the zone knows as Afuera. The zones of greatest R. typus density within the WSBR were characterized by high Chl a concentrations (median: 1·1 mg m-3 , interpercentile range: 0·5-1·8 mg m-3 ) and high nutrient concentrations, such as ammonium (median: 2·5 µmol l-1 , interpercentile range: 0·5-6·4 µmol l-1 ), due to the influence of local upwelling. A generalized additive model (GAM) was used to explore the relationship between R. typus distribution and the environmental variables inside WSBR. Zooplankton biomass was the most influential environmental variable, supporting the close relationship between R. typus distribution and biological productivity. Copepods were the dominant zooplankton group within the WSBR. In the Afuera zone, there were large R. typus aggregations (>80 individuals) associated with zooplankton dominated by fish eggs and significantly higher mean ± s.d. biomass (3356·1 ± 1960·8 mg m-3 ) compared with that recorded inside the WSBR (103·5 ± 57·2 mg m-3 ). The differences among zones generated changes in R. typus distribution patterns and provided opportunities to develop local management strategies for this species.
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Affiliation(s)
- N Cárdenas-Palomo
- Centro de Investigación y Estudios Avanzados del IPN, Carr. Antigua a Progreso km. 6 Merida, Yucatan 97310, Mexico
| | - J Herrera-Silveira
- Centro de Investigación y Estudios Avanzados del IPN, Carr. Antigua a Progreso km. 6 Merida, Yucatan 97310, Mexico
| | - I Velázquez-Abunader
- Centro de Investigación y Estudios Avanzados del IPN, Carr. Antigua a Progreso km. 6 Merida, Yucatan 97310, Mexico
| | - O Reyes
- Centro de Investigación y Estudios Avanzados del IPN, Carr. Antigua a Progreso km. 6 Merida, Yucatan 97310, Mexico
| | - U Ordoñez
- Centro de Investigación y Estudios Avanzados del IPN, Carr. Antigua a Progreso km. 6 Merida, Yucatan 97310, Mexico
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60
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Dove ADM. Foraging and ingestive behaviors of whale sharks, Rhincodon typus, in response to chemical stimulus cues. THE BIOLOGICAL BULLETIN 2015; 228:65-74. [PMID: 25745101 DOI: 10.1086/bblv228n1p65] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
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. Whale sharks exhibited pronounced ingestive and search behaviors when exposed to both types of stimuli, compared to control trials. Ingestive behaviors included open mouth swimming and active surface feeding (gulping). These behaviors were stronger and more prevalent in response to krill homogenate plumes than to DMS plumes. Both chemical stimuli also increased visitation rate, and krill homogenate plumes additionally affected swimming speed. Whale sharks use chemosensory cues of multiple types to locate and identify palatable food, suggesting that chemical stimuli can help direct long-range movements and allow discrimination of different food items. There appears to be a hierarchy of responses: krill metabolites directly associated with food produced more frequent and intense feeding responses relative to DMS, which is indirectly associated with krill. DMS is used to find food by a number of pelagic species and may be an important signaling molecule in pelagic food webs.
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Hsu HH, Lin CY, Joung SJ. The first record, tagging and release of a neonatal whale shark Rhincodon typus in Taiwan. JOURNAL OF FISH BIOLOGY 2014; 85:1753-1756. [PMID: 25199804 DOI: 10.1111/jfb.12498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 07/09/2014] [Indexed: 06/03/2023]
Abstract
On 27 October 2013, a Rhincodon typus was apparently chased by a group of Caranx ignobilis into nearshore waters near Green Island (Ludao), east of Taiwan. A fisherman brought it back to port where it was kept in a small sea pen until release. The R. typus was 78 cm total length, and was tagged and released on 29 October 2013.
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Affiliation(s)
- H H Hsu
- Department of Environmental Biology and Fisheries Science, National Taiwan Ocean University, 2 Pei-Ning Road, Keelung 20224, Taiwan; George Chen Shark Research Center, National Taiwan Ocean University, 2 Pei-Ning Road, Keelung 20224, Taiwan
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Abstract
AbstractThe whale shark Rhincodon typus is a popular focal species in the marine tourism industry. We analysed 689 encounters with at least 142 individual sharks during 2008–2010 to assess their behaviour in the presence of swimmers at Tofo Beach, Mozambique. Sharks varied in size (estimated 3.0–9.5 m total length) and the majority (74%) were males. The sharks displayed avoidance behaviours during 64.7% of encounters. Encounter duration decreased significantly, from 12 minutes 37 s with undisturbed sharks to 8 minutes 25 s when sharks expressed avoidance behaviours, indicating that interactions with tourists affected the sharks’ short-term behaviour. However, during the 2.5-year study period we found no trend in the mean encounter duration, the overall expression of avoidance behaviour or the likelihood of an individual shark exhibiting avoidance behaviours. Potential effects of tourism may be mitigated by the non-breeding status and transient behaviour of sharks at this aggregation site.
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Carbone C, Codron D, Scofield C, Clauss M, Bielby J. Geometric factors influencing the diet of vertebrate predators in marine and terrestrial environments. Ecol Lett 2014; 17:1553-9. [PMID: 25265992 PMCID: PMC4284001 DOI: 10.1111/ele.12375] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/06/2014] [Accepted: 08/27/2014] [Indexed: 11/28/2022]
Abstract
Predator–prey relationships are vital to ecosystem function and there is a need for greater predictive understanding of these interactions. We develop a geometric foraging model predicting minimum prey size scaling in marine and terrestrial vertebrate predators taking into account habitat dimensionality and biological traits. Our model predicts positive predator–prey size relationships on land but negative relationships in the sea. To test the model, we compiled data on diets of 794 predators (mammals, snakes, sharks and rays). Consistent with predictions, both terrestrial endotherm and ectotherm predators have significantly positive predator–prey size relationships. Marine predators, however, exhibit greater variation. Some of the largest predators specialise on small invertebrates while others are large vertebrate specialists. Prey–predator mass ratios were generally higher for ectothermic than endothermic predators, although dietary patterns were similar. Model-based simulations of predator–prey relationships were consistent with observed relationships, suggesting that our approach provides insights into both trends and diversity in predator–prey interactions.
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Affiliation(s)
- Chris Carbone
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
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65
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Berumen ML, Braun CD, Cochran JEM, Skomal GB, Thorrold SR. Movement patterns of juvenile whale sharks tagged at an aggregation site in the Red Sea. PLoS One 2014; 9:e103536. [PMID: 25076407 PMCID: PMC4116204 DOI: 10.1371/journal.pone.0103536] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 07/01/2014] [Indexed: 11/18/2022] Open
Abstract
Conservation efforts aimed at the whale shark, Rhincodon typus, remain limited by a lack of basic information on most aspects of its ecology, including global population structure, population sizes and movement patterns. Here we report on the movements of 47 Red Sea whale sharks fitted with three types of satellite transmitting tags from 2009-2011. Most of these sharks were tagged at a single aggregation site near Al-Lith, on the central coast of the Saudi Arabian Red Sea. Individuals encountered at this site were all juveniles based on size estimates ranging from 2.5-7 m total length with a sex ratio of approximately 1∶1. All other known aggregation sites for juvenile whale sharks are dominated by males. Results from tagging efforts showed that most individuals remained in the southern Red Sea and that some sharks returned to the same location in subsequent years. Diving data were recorded by 37 tags, revealing frequent deep dives to at least 500 m and as deep as 1360 m. The unique temperature-depth profiles of the Red Sea confirmed that several whale sharks moved out of the Red Sea while tagged. The wide-ranging horizontal movements of these individuals highlight the need for multinational, cooperative efforts to conserve R. typus populations in the Red Sea and Indian Ocean.
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Affiliation(s)
- Michael L Berumen
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Camrin D Braun
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia; Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
| | - Jesse E M Cochran
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Gregory B Skomal
- Massachusetts Division of Marine Fisheries, New Bedford, Massachusetts, United States of America
| | - Simon R Thorrold
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
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66
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Vinther J, Stein M, Longrich NR, Harper DAT. A suspension-feeding anomalocarid from the Early Cambrian. Nature 2014; 507:496-9. [DOI: 10.1038/nature13010] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 01/09/2014] [Indexed: 11/09/2022]
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67
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Sequeira AMM, Mellin C, Fordham DA, Meekan MG, Bradshaw CJA. Predicting current and future global distributions of whale sharks. GLOBAL CHANGE BIOLOGY 2014; 20:778-789. [PMID: 23907987 DOI: 10.1111/gcb.12343] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Revised: 06/27/2013] [Accepted: 07/20/2013] [Indexed: 06/02/2023]
Abstract
The Vulnerable (IUCN) whale shark spans warm and temperate waters around the globe. However, their present-day and possible future global distribution has never been predicted. Using 30 years (1980-2010) of whale shark observations recorded by tuna purse-seiners fishing in the Atlantic, Indian and Pacific Oceans, we applied generalized linear mixed-effects models to test the hypothesis that similar environmental covariates predict whale shark occurrence in all major ocean basins. We derived global predictors from satellite images for chlorophyll a and sea surface temperature, and bathymetric charts for depth, bottom slope and distance to shore. We randomly generated pseudo-absences within the area covered by the fisheries, and included fishing effort as an offset to account for potential sampling bias. We predicted sea surface temperatures for 2070 using an ensemble of five global circulation models under a no climate-policy reference scenario, and used these to predict changes in distribution. The full model (excluding standard deviation of sea surface temperature) had the highest relative statistical support (wAICc = 0.99) and explained ca. 60% of the deviance. Habitat suitability was mainly driven by spatial variation in bathymetry and sea surface temperature among oceans, although these effects differed slightly among oceans. Predicted changes in sea surface temperature resulted in a slight shift of suitable habitat towards the poles in both the Atlantic and Indian Oceans (ca. 5°N and 3-8°S, respectively) accompanied by an overall range contraction (2.5-7.4% and 1.1-6.3%, respectively). Predicted changes in the Pacific Ocean were small. Assuming that whale shark environmental requirements and human disturbances (i.e. no stabilization of greenhouse gas emissions) remain similar, we show that warming sea surface temperatures might promote a net retreat from current aggregation areas and an overall redistribution of the species.
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Affiliation(s)
- Ana M M Sequeira
- The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, South Australia, 5005, Australia
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68
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Experimental evaluation of shark detection rates by aerial observers. PLoS One 2014; 9:e83456. [PMID: 24498258 PMCID: PMC3911894 DOI: 10.1371/journal.pone.0083456] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 11/04/2013] [Indexed: 11/29/2022] Open
Abstract
Aerial surveys are a recognised technique to identify the presence and abundance of marine animals. However, the capability of aerial observers to reliably sight coastal sharks has not been previously assessed, nor have differences in sighting rates between aircraft types been examined. In this study we investigated the ability of observers in fixed-wing and helicopter aircraft to sight 2.5 m artificial shark analogues placed at known depths and positions. Initial tests revealed that the shark analogues could only be detected at shallow depths, averaging only 2.5 m and 2.7 m below the water surface for observers in fixed-wing and helicopter aircraft, respectively. We then deployed analogues at shallower depths along a 5 km-long grid, and assessed their sightability to aircraft observers through a series of transects flown within 500 m. Analogues were seen infrequently from all distances, with overall sighting rates of only 12.5% and 17.1% for fixed-wing and helicopter observers, respectively. Although helicopter observers had consistently higher success rates of sighting analogues within 250 m of their flight path, neither aircraft observers sighted more than 9% of analogues deployed over 300 m from their flight paths. Modelling of sighting rates against environmental and experimental variables indicated that observations were affected by distance, aircraft type, sun glare and sea conditions, while the range of water turbidities observed had no effect. We conclude that aerial observers have limited ability to detect the presence of submerged animals such as sharks, particularly when the sharks are deeper than ∼2.6 m, or over 300 m distant from the aircraft's flight path, especially during sunny or windy days. The low rates of detections found in this study cast serious doubts on the use of aerial beach patrols as an effective early-warning system to prevent shark attacks.
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69
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Misty Paig-Tran EW, Summers AP. Comparison of the structure and composition of the branchial filters in suspension feeding elasmobranchs. Anat Rec (Hoboken) 2014; 297:701-15. [PMID: 24443216 DOI: 10.1002/ar.22850] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 11/05/2013] [Indexed: 11/12/2022]
Abstract
The four, evolutionarily independent, lineages of suspension feeding elasmobranchs have two types of branchial filters. The first is a robust, flattened filter pad akin to a colander (e.g., whale sharks, mantas and devil rays) while the second more closely resembles the comb-like gill raker structure found in bony fishes (e.g., basking and megamouth sharks). The structure and the presence of mucus on the filter elements will determine the mechanical function of the filter and subsequent particle transport. Using histology and scanning electron microscopy, we investigated the anatomy of the branchial filters in 12 of the 14 species of Chondrichthyian filter-feeding fishes. We hypothesized that mucus producing cells would be abundant along the filter epithelium and perform as a sticky mechanism to retain and transport particles; however, we found that only three species had mucus producing goblet cells. Two of these (Mobula kuhlii and Mobula tarapacana) also had branchial cilia, indicating sticky retention and transport. The remaining filter-feeding elasmobranchs did not have a sticky surface along the filter for particles to collect and instead must employ alternative mechanisms of filtration (e.g., direct sieving, inertial impaction or cross-flow). With the exception of basking sharks, the branchial filter is composed of a hyaline cartilage skeleton surrounded by a layer of highly organized connective tissue that may function as a support. Megamouth sharks and most of the mobulid rays have denticles along the surface of the filter, presumably to protect against damage from large particle impactions. Basking sharks have branchial filters that lack a cartilaginous core; instead they are composed entirely of smooth keratin.
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Affiliation(s)
- E W Misty Paig-Tran
- Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington
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70
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Smith JC, Sanderson SL. Particle retention in suspension-feeding fish after removal of filtration structures. ZOOLOGY 2013; 116:348-55. [PMID: 24211074 DOI: 10.1016/j.zool.2013.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/18/2013] [Accepted: 08/26/2013] [Indexed: 11/26/2022]
Abstract
The suspension-feeding cichlids Oreochromis aureus (blue tilapia) and Oreochromis esculentus (ngege tilapia) are able to selectively retain small food particles. The gill rakers and microbranchiospines of these species have been assumed to function as filters. However, surgical removal of these oral structures, which also removed associated mucus, did not significantly affect the total number of 11-200 μm particles ingested by the fish. This result supports the hypothesis that the branchial arch surfaces themselves play an important role in crossflow filtration. Both species selectively retained microspheres greater than 50 μm with gill rakers and microbranchiospines intact as well as removed, demonstrating that neither these structures nor mucus are necessary for size selectivity to occur during biological crossflow filtration. After removal of the gill rakers and microbranchiospines, O. esculentus retained significantly more microspheres 51-70 μm in diameter and fewer 91-130 μm microspheres compared to retention with intact structures, but the particle size selectivity of O. aureus was not affected significantly. These results support conclusions from previous computational fluid dynamics simulations indicating that particle size can have marked effects on particle trajectory and retention inside the fish oropharyngeal cavity during crossflow filtration. The substantial inter-individual variability in particle retention by suspension-feeding fish is an unexplored area of research with the potential to increase our understanding of the factors influencing particle retention during biological filtration.
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Affiliation(s)
- Jennifer C Smith
- Department of Biology, College of William & Mary, Williamsburg, VA 23187-8795, USA
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71
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Fox S, Foisy I, De La Parra Venegas R, Galván Pastoriza BE, Graham RT, Hoffmayer ER, Holmberg J, Pierce SJ. Population structure and residency of whale sharks Rhincodon typus at Utila, Bay Islands, Honduras. JOURNAL OF FISH BIOLOGY 2013; 83:574-87. [PMID: 23991875 DOI: 10.1111/jfb.12195] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Accepted: 06/13/2013] [Indexed: 05/26/2023]
Abstract
There were 479 reported whale shark Rhincodon typus encounters between 1999 and 2011 at the island of Utila, which forms part of the Meso-American Barrier Reef System (MBRS) in the western Caribbean Sea. The majority of R. typus were found to feed on small bait fish associated with various tuna species. Ninety-five individual R. typus, ranging from 2 to 11 m total length (LT ), were identified through their unique spot patterns. A significant male bias (65%) was present. There was no significant difference between the mean ± s.d. LT of female (6·66 ± 1·65 m) and male (6·25 ± 1·60 m) R. typus. Most R. typus were transient to Utila, with 78% sighted only within a single calendar year, although some individuals were sighted in up to 5 years. Mean residency time was modelled to be 11·76 days using maximum likelihood methods.
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Affiliation(s)
- S Fox
- Utila Whale Shark Research, Utila, Honduras
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72
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Couturier LIE, Rohner CA, Richardson AJ, Pierce SJ, Marshall AD, Jaine FRA, Townsend KA, Bennett MB, Weeks SJ, Nichols PD. Unusually high levels of n-6 polyunsaturated fatty acids in whale sharks and reef manta rays. Lipids 2013; 48:1029-34. [PMID: 23975574 PMCID: PMC3779593 DOI: 10.1007/s11745-013-3829-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 08/02/2013] [Indexed: 11/28/2022]
Abstract
Fatty acid (FA) signature analysis has been increasingly used to assess dietary preferences and trophodynamics in marine animals. We investigated FA signatures of connective tissue of the whale shark Rhincodon typus and muscle tissue of the reef manta ray Manta alfredi. We found high levels of n-6 polyunsaturated fatty acids (PUFA), dominated by arachidonic acid (20:4n-6; 12–17 % of total FA), and comparatively lower levels of the essential n-3 PUFA—eicosapentaenoic acid (20:5n-3; ~1 %) and docosahexaenoic acid (22:6n-3; 3–10 %). Whale sharks and reef manta rays are regularly observed feeding on surface aggregations of coastal crustacean zooplankton during the day, which generally have FA profiles dominated by n-3 PUFA. The high levels of n-6 PUFA in both giant elasmobranchs raise new questions about the origin of their main food source.
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Affiliation(s)
- L I E Couturier
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, 4072, Australia,
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73
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Hueter RE, Tyminski JP, de la Parra R. Horizontal movements, migration patterns, and population structure of whale sharks in the Gulf of Mexico and northwestern Caribbean sea. PLoS One 2013; 8:e71883. [PMID: 23991000 PMCID: PMC3749210 DOI: 10.1371/journal.pone.0071883] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 07/05/2013] [Indexed: 11/19/2022] Open
Abstract
Whale sharks, Rhincodon typus, aggregate by the hundreds in a summer feeding area off the northeastern Yucatan Peninsula, Mexico, where the Gulf of Mexico meets the Caribbean Sea. The aggregation remains in the nutrient-rich waters off Isla Holbox, Isla Contoy and Isla Mujeres, Quintana Roo for several months in the summer and then dissipates between August and October. Little has been known about where these sharks come from or migrate to after they disperse. From 2003-2012, we used conventional visual tags, photo-identification, and satellite tags to characterize the basic population structure and large-scale horizontal movements of whale sharks that come to this feeding area off Mexico. The aggregation comprised sharks ranging 2.5-10.0 m in total length and included juveniles, subadults, and adults of both sexes, with a male-biased sex ratio (72%). Individual sharks remained in the area for an estimated mean duration of 24-33 days with maximum residency up to about 6 months as determined by photo-identification. After leaving the feeding area the sharks showed horizontal movements in multiple directions throughout the Gulf of Mexico basin, the northwestern Caribbean Sea, and the Straits of Florida. Returns of individual sharks to the Quintana Roo feeding area in subsequent years were common, with some animals returning for six consecutive years. One female shark with an estimated total length of 7.5 m moved at least 7,213 km in 150 days, traveling through the northern Caribbean Sea and across the equator to the South Atlantic Ocean where her satellite tag popped up near the Mid-Atlantic Ridge. We hypothesize this journey to the open waters of the Mid-Atlantic was for reproductive purposes but alternative explanations are considered. The broad movements of whale sharks across multiple political boundaries corroborates genetics data supporting gene flow between geographically distinct areas and underscores the need for management and conservation strategies for this species on a global scale.
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Affiliation(s)
- Robert E. Hueter
- Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America
| | - John P. Tyminski
- Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America
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74
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Paig-Tran EM, Kleinteich T, Summers AP. The filter pads and filtration mechanisms of the devil rays: Variation at macro and microscopic scales. J Morphol 2013; 274:1026-43. [DOI: 10.1002/jmor.20160] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 03/22/2013] [Accepted: 03/26/2013] [Indexed: 11/07/2022]
Affiliation(s)
- E.W. Misty Paig-Tran
- Department of Biology; Friday Harbor Laboratories; University of Washington; Friday Harbor; WA; 98250
| | - Thomas Kleinteich
- Department of Zoology; Christian-Albrechts-Universität; Christian-Albrechts-Platz 4; 24118; Kiel; Germany
| | - Adam P. Summers
- Department of Biology; Friday Harbor Laboratories; University of Washington; Friday Harbor; WA; 98250
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75
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Robinson DP, Jaidah MY, Jabado RW, Lee-Brooks K, Nour El-Din NM, Al Malki AA, Elmeer K, McCormick PA, Henderson AC, Pierce SJ, Ormond RFG. Whale sharks, Rhincodon typus, aggregate around offshore platforms in Qatari waters of the Arabian Gulf to feed on fish spawn. PLoS One 2013; 8:e58255. [PMID: 23516456 PMCID: PMC3596407 DOI: 10.1371/journal.pone.0058255] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 02/05/2013] [Indexed: 11/19/2022] Open
Abstract
Whale sharks, Rhincodon typus, are known to aggregate to feed in a small number of locations in tropical and subtropical waters. Here we document a newly discovered major aggregation site for whale sharks within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. Whale sharks were observed between April and September, with peak numbers observed between May and August. Density estimates of up to 100 sharks within an area of 1 km(2) were recorded. Sharks ranged between four and eight metres' estimated total length (mean 6.92 ± 1.53 m). Most animals observed were actively feeding on surface zooplankton, consisting primarily of mackerel tuna, Euthynnus affinis, eggs.
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76
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Sequeira AMM, Mellin C, Meekan MG, Sims DW, Bradshaw CJA. Inferred global connectivity of whale shark Rhincodon typus populations. JOURNAL OF FISH BIOLOGY 2013; 82:367-89. [PMID: 23398057 DOI: 10.1111/jfb.12017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 11/05/2012] [Indexed: 05/06/2023]
Abstract
Ten years have passed since the last synopsis of whale shark Rhincodon typus biogeography. While a recent review of the species' biology and ecology summarized the vast data collected since then, it is clear that information on population geographic connectivity, migration and demography of R. typus is still limited and scattered. Understanding R. typus migratory behaviour is central to its conservation management considering the genetic evidence suggesting local aggregations are connected at the generational scale over entire ocean basins. By collating available data on sightings, tracked movements and distribution information, this review provides evidence for the hypothesis of broad-scale connectivity among populations, and generates a model describing how the world's R. typus are part of a single, global meta-population. Rhincodon typus occurrence timings and distribution patterns make possible a connection between several aggregation sites in the Indian Ocean. The present conceptual model and validating data lend support to the hypothesis that R. typus are able to move among the three largest ocean basins with a minimum total travelling time of around 2-4 years. The model provides a worldwide perspective of possible R. typus migration routes, and suggests a modified focus for additional research to test its predictions. The framework can be used to trim the hypotheses for R. typus movements and aggregation timings, thereby isolating possible mating and breeding areas that are currently unknown. This will assist endeavours to predict the longer-term response of the species to ocean warming and changing patterns of human-induced mortality.
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Affiliation(s)
- A M M Sequeira
- The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, SA, Australia.
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77
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Andrades R, Pinheiro HT, Santos RG, Martins AS, Costa PAS. A new record of whale shark Rhincodon typus in Brazilian waters: a report of association with Caranx crysos. JOURNAL OF FISH BIOLOGY 2012; 81:2092-2094. [PMID: 23130705 DOI: 10.1111/j.1095-8649.2012.03460.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In May 2011, a Rhincodon typus was sighted on the continental shelf of the central Brazilian coast, in the vicinity of a gas platform. During the video record, an interspecific following association was observed between a Caranx crysos school and the R. typus.
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Affiliation(s)
- R Andrades
- Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Goiabeiras, Vitória, Espirito Santo, Brazil.
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78
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Ramírez-Macías D, Meekan M, De La Parra-Venegas R, Remolina-Suárez F, Trigo-Mendoza M, Vázquez-Juárez R. Patterns in composition, abundance and scarring of whale sharks Rhincodon typus near Holbox Island, Mexico. JOURNAL OF FISH BIOLOGY 2012; 80:1401-1416. [PMID: 22497390 DOI: 10.1111/j.1095-8649.2012.03258.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Photo-identification and conventional tagging were used to estimate population size and structure of the whale shark Rhincodon typus near Holbox Island, Mexico. From 2005 to 2008, photographs of spot patterns behind the last gill slit and in a lateral view on the left side of each animal were used to identify individuals. Additionally, 578 R. typus were tagged using conventional marker tags. Of these and the 350 R. typus that were identified from 1184 photographs, 65% were male; 27%, female and 8%, indeterminate sex. Photographed R. typus ranged in size from 2·5 to 9·5 m total length. Size was bimodal with a large peak at 6 m and a smaller peak at 7 m. Photo-identification showed that there was considerable loss of marker tags. Few of these remained on the animals for more than a year, so that interannual re-sights using tagging could not be used in population modelling. Forty six interannual re-sightings were found in the photographic library; the interval between these re-sightings was typically 1 year. It was estimated that the R. typus aggregation near Holbox Island ranged from 521 to 809 individuals, based on mark-recapture models. From 13 to 33% of R. typus photographed had scars that were attributable to boat strikes. This study provides a baseline for assessing the status of R. typus near Holbox Island. This information is useful to understand drivers of local population size and distribution and potential concerns about increasing effects of tourism on R. typus in this area and for designing better management programmes for R. typus conservation.
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Affiliation(s)
- D Ramírez-Macías
- Centro de Investigaciones Biológicas del Noroeste, Mar Bermejo 195, Col. Playa Palo de Santa Rita, La Paz, B.C.S. 23096, Mexico
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79
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Rowat D, Brooks KS. A review of the biology, fisheries and conservation of the whale shark Rhincodon typus. JOURNAL OF FISH BIOLOGY 2012; 80:1019-56. [PMID: 22497372 DOI: 10.1111/j.1095-8649.2012.03252.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Although the whale shark Rhincodon typus is the largest extant fish, it was not described until 1828 and by 1986 there were only 320 records of this species. Since then, growth in tourism and marine recreation globally has lead to a significant increase in the number of sightings and several areas with annual occurrences have been identified, spurring a surge of research on the species. Simultaneously, there was a great expansion in targeted R. typus fisheries to supply the Asian restaurant trade, as well as a largely un-quantified by-catch of the species in purse-seine tuna fisheries. Currently R. typus is listed by the IUCN as vulnerable, due mainly to the effects of targeted fishing in two areas. Photo-identification has shown that R. typus form seasonal size and sex segregated feeding aggregations and that a large proportion of fish in these aggregations are philopatric in the broadest sense, tending to return to, or remain near, a particular site. Somewhat conversely, satellite tracking studies have shown that fish from these aggregations can migrate at ocean-basin scales and genetic studies have, to date, found little graphic differentiation globally. Conservation approaches are now informed by observational and environmental studies that have provided insight into the feeding habits of the species and its preferred habitats. Notwithstanding these advances, there remain notable gaps in the knowledge of this species particularly with respect to the life history of neonates and adults who are not found in the feeding aggregations.
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Affiliation(s)
- D Rowat
- Marine Conservation Society Seychelles, P. O. Box 1299, Victoria, Mahe, Seychelles.
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80
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Paig-Tran EWM, Bizzarro JJ, Strother JA, Summers AP. Bottles as models: predicting the effects of varying swimming speed and morphology on size selectivity and filtering efficiency in fishes. J Exp Biol 2011; 214:1643-54. [DOI: 10.1242/jeb.048702] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
We created physical models based on the morphology of ram suspension-feeding fishes to better understand the roles morphology and swimming speed play in particle retention, size selectivity and filtration efficiency during feeding events. We varied the buccal length, flow speed and architecture of the gills slits, including the number, size, orientation and pore size/permeability, in our models. Models were placed in a recirculating flow tank with slightly negatively buoyant plankton-like particles (∼20–2000 μm) collected at the simulated esophagus and gill rakers to locate the highest density of particle accumulation. Particles were captured through sieve filtration, direct interception and inertial impaction. Changing the number of gill slits resulted in a change in the filtration mechanism of particles from a bimodal filter, with very small (≤50 μm) and very large (>1000 μm) particles collected, to a filter that captured medium-sized particles (101–1000 μm). The number of particles collected on the gill rakers increased with flow speed and skewed the size distribution towards smaller particles (51–500 μm). Small pore sizes (105 and 200 μm mesh size) had the highest filtration efficiencies, presumably because sieve filtration played a significant role. We used our model to make predictions about the filtering capacity and efficiency of neonatal whale sharks. These results suggest that the filtration mechanics of suspension feeding are closely linked to an animal's swimming speed and the structural design of the buccal cavity and gill slits.
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Affiliation(s)
- E. W. Misty Paig-Tran
- Friday Harbor Laboratories, University of Washington, 620 University Road, Friday Harbor, WA 98250, USA
| | - Joseph J. Bizzarro
- School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98195-5020, USA
| | - James A. Strother
- University of California Irvine, 321 Steinhaus, Irvine, CA 92697, USA
| | - Adam P. Summers
- Friday Harbor Laboratories, University of Washington, 620 University Road, Friday Harbor, WA 98250, USA
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81
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de la Parra Venegas R, Hueter R, González Cano J, Tyminski J, Gregorio Remolina J, Maslanka M, Ormos A, Weigt L, Carlson B, Dove A. An unprecedented aggregation of whale sharks, Rhincodon typus, in Mexican coastal waters of the Caribbean Sea. PLoS One 2011; 6:e18994. [PMID: 21559508 PMCID: PMC3084747 DOI: 10.1371/journal.pone.0018994] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 03/25/2011] [Indexed: 11/24/2022] Open
Abstract
Whale sharks, Rhincodon typus, are often perceived as solitary behemoths that live and feed in the open ocean. To the contrary, evidence is accumulating that they are gregarious and form seasonal aggregations in some coastal waters. One such aggregation occurs annually north of Cabo Catoche, off Isla Holbox on the Yucatán Peninsula of Mexico. Here we report a second, much denser aggregation of whale sharks (dubbed “the Afuera”) that occurs east of the tip of the Yucatán Peninsula in the Caribbean Sea. The 2009 Afuera event comprised the largest aggregation of whale sharks ever reported, with up to 420 whale sharks observed in a single aerial survey, all gathered in an elliptical patch of ocean approximately 18 km2. Plankton studies indicated that the sharks were feeding on dense homogenous patches of fish eggs, which DNA barcoding analysis identified as belonging to little tunny, Euthynnus alletteratus. This contrasts with the annual Cabo Catoche aggregation nearby, where prey consists mostly of copepods and sergestid shrimp. Increased sightings at the Afuera coincide with decreased sightings at Cabo Catoche, and both groups have the same sex ratio, implying that the same animals are likely involved in both aggregations; tagging data support this idea. With two whale shark aggregation areas, high coastal productivity and a previously-unknown scombrid spawning ground, the northeastern Yucatán marine region is a critical habitat that deserves more concerted conservation efforts.
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Affiliation(s)
| | - Robert Hueter
- Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America
| | - Jaime González Cano
- Proyecto Dominó, Comisión Nacional de Áreas Naturales Protegidas, Cancún, Quintana Roo, México
| | - John Tyminski
- Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America
| | - José Gregorio Remolina
- Proyecto Dominó, Comisión Nacional de Áreas Naturales Protegidas, Cancún, Quintana Roo, México
| | - Mike Maslanka
- Smithsonian Conservation Biology Institute, National Zoological Park, Washington, D.C., United States of America
| | - Andrea Ormos
- Laboratories of Analytical Biology, National Museum of Natural History, Smithsonian Institution, Washington, D.C., United States of America
| | - Lee Weigt
- Laboratories of Analytical Biology, National Museum of Natural History, Smithsonian Institution, Washington, D.C., United States of America
| | - Bruce Carlson
- Georgia Aquarium Research Center, Georgia Aquarium, Atlanta, Georgia, United States of America
| | - Alistair Dove
- Georgia Aquarium Research Center, Georgia Aquarium, Atlanta, Georgia, United States of America
- * E-mail:
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Gleiss AC, Norman B, Wilson RP. Moved by that sinking feeling: variable diving geometry underlies movement strategies in whale sharks. Funct Ecol 2010. [DOI: 10.1111/j.1365-2435.2010.01801.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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