scholarly journals Demographics and feeding ecology of whale sharks at Mafia Island, Tanzania

2013 ◽  
Author(s):  
Edgar F Cagua ◽  
Jesse Cochran ◽  
Chris Rohner ◽  
Mathias M Igulu ◽  
Jason Rubens ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Site Fidelity ◽  
Western Indian Ocean ◽  
Sampling Effort ◽  
Whale Shark ◽  
Important Region ◽  
Whale Sharks ◽  
Acoustic Array ◽  
And Gender ◽  
Almost All

Background. The Western Indian Ocean is a globally important region for the whale shark Rhincodon typus, with well-studied coastal aggregation sites in southern Mozambique, Seychelles and Djibouti. Here we present an overview of a new study at Mafia Island, Tanzania. Methods. We monitored whale shark abundances on 103 boat trips from October 2012–March 2013. We also used passive acoustic telemetry (VEMCO® V16 tags) and photographic identification to monitor the residency times and local movements of 29 tagged individuals. Shark sizes were estimated using laser photogrammetry. Results. In total we observed 87 individual sharks with a mean of 5.1 ± 5.2 (± SD) per trip and a peak in December of 8.2 ± 6.3. Total length ranged from 4.1 to 9.7 m and almost all sharks were immature. After boat-based visual observations dropped to zero in March 2013 (with the same ongoing sampling effort), the acoustic array still detected 75% of tagged sharks. Tagged individuals were detected by the acoustic array for 73 ± 40 days on average. They showed a strong site fidelity to a 15 km2 area in the inner part of the bay and then progressively moved offshore at the end of the season, matching a decrease in plankton abundance. Sharks were mostly observed feeding on dense patches of the pelagic shrimp Lucifer hanseni, often in association with planktivorous fishes. Photo IDs from 2007-09 and 2012-13 indicate that a large proportion of the juvenile individuals return to Mafia Island each spring-summer. Conclusion. The size range and gender distribution of whale sharks at Mafia Island is similar to other coastal aggregations in the Indian Ocean, but the relatively high site fidelity and residency time stands in contrast.

scholarly journals Demographics and feeding ecology of whale sharks at Mafia Island, Tanzania

2013 ◽  
Author(s):  
Edgar F Cagua ◽  
Jesse Cochran ◽  
Chris Rohner ◽  
Mathias M Igulu ◽  
Jason Rubens ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Site Fidelity ◽  
Western Indian Ocean ◽  
Sampling Effort ◽  
Whale Shark ◽  
Important Region ◽  
Whale Sharks ◽  
Acoustic Array ◽  
And Gender ◽  
Almost All

Background. The Western Indian Ocean is a globally important region for the whale shark Rhincodon typus, with well-studied coastal aggregation sites in southern Mozambique, Seychelles and Djibouti. Here we present an overview of a new study at Mafia Island, Tanzania. Methods. We monitored whale shark abundances on 103 boat trips from October 2012–March 2013. We also used passive acoustic telemetry (VEMCO® V16 tags) and photographic identification to monitor the residency times and local movements of 29 tagged individuals. Shark sizes were estimated using laser photogrammetry. Results. In total we observed 87 individual sharks with a mean of 5.1 ± 5.2 (± SD) per trip and a peak in December of 8.2 ± 6.3. Total length ranged from 4.1 to 9.7 m and almost all sharks were immature. After boat-based visual observations dropped to zero in March 2013 (with the same ongoing sampling effort), the acoustic array still detected 75% of tagged sharks. Tagged individuals were detected by the acoustic array for 73 ± 40 days on average. They showed a strong site fidelity to a 15 km2 area in the inner part of the bay and then progressively moved offshore at the end of the season, matching a decrease in plankton abundance. Sharks were mostly observed feeding on dense patches of the pelagic shrimp Lucifer hansoni, often in association with planktivorous fishes. Photo IDs from 2007-09 and 2012-13 indicate that a large proportion of the juvenile individuals return to Mafia Island each spring-summer. Conclusion. The size range and gender distribution of whale sharks at Mafia Island is similar to other coastal aggregations in the Indian Ocean, but the relatively high site fidelity and residency time stands in contrast.

scholarly journals Demographics and feeding ecology of whale sharks at Mafia Island, Tanzania

2013 ◽  
Author(s):  
Edgar F Cagua ◽  
Jesse Cochran ◽  
Chris Rohner ◽  
Mathias M Igulu ◽  
Jason Rubens ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Site Fidelity ◽  
Western Indian Ocean ◽  
Sampling Effort ◽  
Whale Shark ◽  
Important Region ◽  
Whale Sharks ◽  
Acoustic Array ◽  
And Gender ◽  
Almost All

Background. The Western Indian Ocean is a globally important region for the whale shark Rhincodon typus, with well-studied coastal aggregation sites in southern Mozambique, Seychelles and Djibouti. Here we present an overview of a new study at Mafia Island, Tanzania. Methods. We monitored whale shark abundances on 103 boat trips from October 2012–March 2013. We also used passive acoustic telemetry (VEMCO® V16 tags) and photographic identification to monitor the residency times and local movements of 29 tagged individuals. Shark sizes were estimated using laser photogrammetry. Results. In total we observed 87 individual sharks with a mean of 5.1 ± 5.2 (± SD) per trip and a peak in December of 8.2 ± 6.3. Total length ranged from 4.1 to 9.7 m and almost all sharks were immature. After boat-based visual observations dropped to zero in March 2013 (with the same ongoing sampling effort), the acoustic array still detected 75% of tagged sharks. Tagged individuals were detected by the acoustic array for 73 ± 40 days on average. They showed a strong site fidelity to a 15 km2 area in the inner part of the bay and then progressively moved offshore at the end of the season, matching a decrease in plankton abundance. Sharks were mostly observed feeding on dense patches of the pelagic shrimp Lucifer hanseni, often in association with planktivorous fishes. Photo IDs from 2007-09 and 2012-13 indicate that a large proportion of the juvenile individuals return to Mafia Island each spring-summer. Conclusion. The size range and gender distribution of whale sharks at Mafia Island is similar to other coastal aggregations in the Indian Ocean, but the relatively high site fidelity and residency time stands in contrast.

scholarly journals The ecological connectivity of whale shark aggregations in the Indian Ocean: a photo-identification approach

2016 ◽  
Vol 3 (11) ◽  
pp. 160455 ◽  
Author(s):  
Samantha Andrzejaczek ◽  
Jessica Meeuwig ◽  
David Rowat ◽  
Simon Pierce ◽  
Tim Davies ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Time Frame ◽  
Ocean Basin ◽  
Identification System ◽  
Whale Shark ◽  
Monte Carlo Simulation Study ◽  
Photo Identification ◽  
Christmas Island ◽  
Modelling Studies ◽  
Whale Sharks

Genetic and modelling studies suggest that seasonal aggregations of whale sharks ( Rhincodon typus ) at coastal sites in the tropics may be linked by migration. Here, we used photo-identification (photo-ID) data collected by both citizen scientists and researchers to assess the connectedness of five whale shark aggregation sites across the entire Indian Ocean at timescales of up to a decade. We used the semi-automated program I 3 S (Individual Interactive Identification System) to compare photographs of the unique natural marking patterns of individual whale sharks collected from aggregations at Mozambique, the Seychelles, the Maldives, Christmas Island (Australia) and Ningaloo Reef (Australia). From a total of 6519 photos, we found no evidence of connectivity of whale shark aggregations at ocean-basin scales within the time frame of the study and evidence for only limited connectivity at regional (hundreds to thousands of kilometres) scales. A male whale shark photographed in January 2010 at Mozambique was resighted eight months later in the Seychelles and was the only one of 1724 individuals in the database to be photographed at more than one site. On average, 35% of individuals were resighted at the same site in more than one year. A Monte Carlo simulation study showed that the power of this photo-ID approach to document patterns of emigration and immigration was strongly dependent on both the number of individuals identified in aggregations and the size of resident populations.

scholarly journals Limited latitudinal ranging of juvenile whale sharks in the Western Indian Ocean suggests the existence of regional management units

2018 ◽  
Vol 601 ◽  
pp. 167-183 ◽  
Author(s):  
CEM Prebble ◽  
CA Rohner ◽  
SJ Pierce ◽  
DP Robinson ◽  
MY Jaidah ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Western Indian Ocean ◽  
Management Units ◽  
Regional Management ◽  
Whale Sharks

Catalogue of Afrotropical bees (Hymenoptera: Apoidea: Apiformes)

Zootaxa ◽  
2010 ◽  
Vol 2455 (1) ◽  
pp. 1 ◽  
Author(s):  
CONNAL EARDLEY ◽  
ROSALIND URBAN
Keyword(s):  
Apis Mellifera ◽  
Indian Ocean ◽  
Western Indian Ocean ◽  
Sub Saharan Africa ◽  
Valid Species ◽  
New Combinations ◽  
History Of ◽  
Taxonomic Changes ◽  
Sub Saharan ◽  
And Gender

The purpose of this catalogue is to list the valid names, nomenclatorial history of, and published references to, the known bees of Sub-Saharan Africa and the western Indian Ocean islands, excluding the honey bee (Apis mellifera Linnaeus). An attempt has been made to include references to all publications on Afrotropical bees since Dalla Torre’s (1896) catalogue, up to and including 2009. All publications dealing with each species are listed under the name combination used. This catalogue includes 2755 valid species and 1133 references. Taxonomic changes, such as new name combinations, with correct latinization and gender, are included. The distribution by country, plants visited, hosts (for parasitic bee species) and parasites are recorded, as are the type’s gender, depository and country locality for each described species (valid and invalid). The following new combinations are included: Amegilla cincta conradsi (Strand), Evylaeus aeratus (Kirby), Evylaeus angustissimus (Cockerell), Evylaeus ankaratrense (Benoist), Evylaeus bellulus (Vachal), Evylaeus bianonis (Cockerell), Evylaeus burnupi (Cockerell), Evylaeus calviniellus (Cockerell), Evylaeus camphorellus (Cockerell), Evylaeus cardiurus (Cockerell), Evylaeus cephalinotus (Cockerell), Evylaeus cessulus (Cockerell), Evylaeus clavigerellus (Cockerell), Evylaeus coeruleodorsatus (Strand), Evylaeus coloratipes (Cockerell), Evylaeus constrictulus (Cockerell), Evylaeus cyaneodiscus (Cockerell), Evylaeus deceptus (Smith), Evylaeus diloloensis (Cockerell), Evylaeus diminutellus (Cockerell), Evylaeus discretulus (Cockerell), Evylaeus epichlorus (Cockerell), Evylaeus gastrophilinus (Cockerell), Evylaeus gendettensis (Cockerell), Evylaeus godmanae (Michener), Evylaeus hemicyaneum (Benoist), Evylaeus hirtulinus (Cockerell), Evylaeus kabetiellus (Cockerell), Evylaeus kampalensis (Cockerell), Evylaeus kasuloi (Cockerell), Evylaeus kowitensis (Cockerell), Evylaeus lactescens (Cockerell), Evylaeus lampronotus (Cameron), Evylaeus latibalteatus (Meade-Waldo), Evylaeus latior (Cockerell), Evylaeus leucophenax (Cockerell), Evylaeus morio (Fabricius), Evylaeus macilentus (Benoist), Evylaeus marshalli (Cockerell); Evylaeus matoporum (Cockerell), Evylaeus mediocre (Benoist), Evylaeus meruensis (Friese), Evylaeus meneliki (Friese), Evylaeus mesopolitus (Cockerell), Evylaeus microsellatus (Cockerell), Evylaeus mirifrons (Cockerell), Evylaeus natensis (Cockerell), Evylaeus nigritulinus (Cockerell), Evylaeus nitididorsatus. (Benoist), Evylaeus niveostictus (Cockerell), Evylaeus parvulinus (Cockerell), Evylaeus pastinimimus (Cockerell), Evylaeus percornutus (Cockerell), Evylaeus perihirtus (Cockerell), Evylaeus perileucus (Cockerell), Evylaeus pernitens (Cockerell), Evylaeus pilicornis (Friese), Evylaeus politescens (Cockerell), Evylaeus pulchripes (Cockerell), Evylaeus pulchritarsis (Cockerell), Evylaeus puzeyi (Cockerell), Evylaeus rubrocinctus (Cockerell), Evylaeus rufitarsellus (Cockerell), Evylaeus ruwenzicus (Cockerell), Evylaeus ruwenzoriellus (Cockerell), Evylaeus schubotzi (Strand), Evylaeus sellatiferus (Cockerell), Evylaeus semilucidus (Cockerell), Evylaeus sublautus (Cockerell), Evylaeus submetallicus (Benoist), Evylaeus tenuicornis (Cockerell), Evylaeus tenuivenis (Cockerell), Evylaeus thestis (Cameron), Evylaeus wilkinsoni (Cockerell), Evylaeus windhukensis (Friese), Heriades edentatus (Friese), Lasioglossum lukulense (Cockerell), Lasioglossum simulator (Cockerell), Lipotriches armatipes obscuripes (Friese), Lipotriches fumipennigera (Strand), and Megachile ambigua (Pasteels). One replacement name has been added: Hylaeus multifarius Eardley & Urban.

scholarly journals Seasonal Occurrence, Horizontal Movements, and Habitat Use Patterns of Whale Sharks (Rhincodon typus) in the Gulf of Mexico

2021 ◽  
Vol 7 ◽  
Author(s):  
Eric R. Hoffmayer ◽  
Jennifer A. McKinney ◽  
James S. Franks ◽  
Jill M. Hendon ◽  
William B. Driggers ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Habitat Use ◽  
Continental Shelf ◽  
Site Fidelity ◽  
Seasonal Occurrence ◽  
Whale Shark ◽  
Shelf Edge ◽  
Rhincodon Typus ◽  
Aggregation Site ◽  
Whale Sharks

In the northern Gulf of Mexico (GOM), whale sharks (Rhincodon typus) form large aggregations at continental shelf-edge banks during summer; however, knowledge of movements once they leave aggregation sites is limited. Here we report on the seasonal occurrence of whale sharks in the northern GOM based on over 800 whale shark sightings from 1989 to 2016, as well as the movements of 42 whale sharks tagged with satellite-linked and popup satellite archival transmitting tags from 2008 to 2015. Sightings data were most numerous during summer and fall often with aggregations of individuals reported along the continental shelf break. Most sharks (66%) were tagged during this time at Ewing Bank, a known aggregation site off the coast of Louisiana. Whale shark track duration ranged from three to 366 days and all tagged individuals, which ranged from 4.5 to 12.0 m in total length, remained within the GOM. Sightings data revealed that whale sharks occurred primarily in continental shelf and shelf-edge waters (81%) whereas tag data revealed the sharks primarily inhabited continental slope and open ocean waters (91%) of the GOM. Much of their time spent in open ocean waters was associated with the edge of the Loop Current and associated mesoscale eddies. During cooler months, there was a net movement southward, corresponding with the time of reduced sighting reports. Several sharks migrated to the southwest GOM during fall and winter, suggesting this region could be important overwintering habitat and possibly represents another seasonal aggregation site. The three long-term tracked whale sharks exhibited interannual site fidelity, returning one year later to the vicinity where they were originally tagged. The increased habitat use of north central GOM waters by whale sharks as summer foraging grounds and potential interannual site fidelity to Ewing Bank demonstrate the importance of this region for this species.

scholarly journals Genetic Identification of Anchovy from Cenderawasih Bay using DNA Barcoding Approach

2021 ◽  
pp. 154-166
Author(s):  
Muhammad Dailami ◽  
Yuni Widyawati ◽  
Abdul Hamid A. Toha
Keyword(s):  
Genetic Identification ◽  
Coi Gene ◽  
Whale Shark ◽  
Ecological Studies ◽  
Base Pairs ◽  
Marine Habitat ◽  
Phylogenetic Tree Analysis ◽  
Whale Sharks ◽  
Pcr Method ◽  
Almost All

The Cenderawasih Bay is a marine habitat for whale sharks (R. typus) which appear almost all year round. The appearance of this whale shark is triggered by various factors, including the food. Anchovy is one of the attractions for the emergence of whale sharks, so it is necessary to conduct genetic, biological and ecological studies. Anchovy has a small in size, making it difficult to identify morphologically. The purpose of this study was to genetically identify anchovy samples obtained from Cenderawasih Bay and compare the sequences with the GenBank database. The COI gene fragments were amplified by PCR method, using primer jg-LCO and jg-HCO. Sequencing is carried out from two directions, forward and reverse with the sanger termination dideoxy method. The resulting DNA sequence has a length of 669 base pairs encoding 223 amino acids. The results of homological comparisons with the NCBI and BOLD System databases show that this sample has similarities to the COI sequence of Spratelloides gracilis with a similarity number up to 99%. The results of the phylogenetic tree analysis showed that the anchovy samples from Cenderawasih Bay were in one clade with S. gracilis from Japan and separated from the clade of S. gracilis from the Red Sea, with a distance between clades is 0.104. This result is in line with the identification by homological comparison in the NCBI and BOLD System.

Editorial Introduction

2020 ◽  
Vol 4 (1) ◽  
pp. 1
Author(s):  
Editors of the JIOWS
Keyword(s):  
Nineteenth Century ◽  
Indian Ocean ◽  
Western Indian Ocean ◽  
Late Nineteenth Century ◽  
Fourth Volume ◽  
History Of ◽  
The Indian Ocean ◽  
Complex Relationships ◽  
Indian Ocean World ◽  
Shed Light

The editors are proud to present the first issue of the fourth volume of the Journal of Indian Ocean World Studies. This issue contains three articles, by James Francis Warren (Murdoch University), Kelsey McFaul (University of California, Santa Cruz), and Marek Pawelczak (University of Warsaw), respectively. Warren’s and McFaul’s articles take different approaches to the growing body of work that discusses pirates in the Indian Ocean World, past and present. Warren’s article is historical, exploring the life and times of Julano Taupan in the nineteenth-century Philippines. He invites us to question the meaning of the word ‘pirate’ and the several ways in which Taupan’s life has been interpreted by different European colonists and by anti-colonial movements from the mid-nineteenth century to the present day. McFaul’s article, meanwhile, takes a literary approach to discuss the much more recent phenomenon of Somali Piracy, which reached its apex in the last decade. Its contribution is to analyse the works of authors based in the region, challenging paradigms that have mostly been developed from analysis of works written in the West. Finally, Pawelczak’s article is a legal history of British jurisdiction in mid-late nineteenth-century Zanzibar. It examines one of the facets that underpinned European influence in the western Indian Ocean World before the establishment of colonial rule. In sum, this issue uses two key threads to shed light on the complex relationships between European and other Western powers and the Indian Ocean World.

scholarly journals Factors influencing microbial mat composition, distribution and dinitrogen fixation in three western Indian Ocean coral reefs

2012 ◽  
Vol 47 (1) ◽  
pp. 51-66 ◽  
Author(s):  
Loïc Charpy ◽  
Katarzyna A. Palinska ◽  
Raeid M. M. Abed ◽  
Marie José Langlade ◽  
Stjepko Golubic
Keyword(s):  
Indian Ocean ◽  
Coral Reefs ◽  
Western Indian Ocean ◽  
Dinitrogen Fixation ◽  
Microbial Mat ◽  
Composition Distribution ◽  
Factors Influencing

scholarly journals Movement ecology of black marlin Istiompax indica in the Western Indian Ocean

2021 ◽  
Author(s):  
Christoph A. Rohner ◽  
Roy Bealey ◽  
Bernerd M. Fulanda ◽  
Jason D. Everett ◽  
Anthony J. Richardson ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Movement Ecology ◽  
Western Indian Ocean
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