scholarly journals Is Host Ectoparasite Load Related to Echeneid Fish Presence?

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Gonzalo R. Mucientes ◽  
Nuno Queiroz ◽  
Simon J. Pierce ◽  
Ivan Sazima ◽  
Juerg M. Brunnschweiler
Keyword(s):  
Host Species ◽  
Field Data ◽  
Free Swimming ◽  
Rhincodon Typus ◽  
Isurus Oxyrinchus ◽  
Whale Sharks ◽  
Ectoparasite Load

This study used field data of echeneid and ectoparasite associations with free-swimming whale sharks (Rhincodon typus) and captured mako sharks (Isurus oxyrinchus) to test whether (1) echeneid presence was positively correlated with ectoparasite presence; and (2) the number of ectoparasites was negatively correlated with the number of echeneid fish. Data from whale and mako sharks do not support the first hypothesis whereas data from mako sharks yields support for the second hypothesis. The results indicate that echeneids do regulate the number of ectoparasites on at least some host species, but these benefits may be contingent on the echeneid species.

Comparing length-measurement methods and estimating growth parameters of free-swimming whale sharks (Rhincodon typus) near the South Ari Atoll, Maldives

2018 ◽  
Vol 69 (10) ◽  
pp. 1487 ◽  
Author(s):  
Cameron T. Perry ◽  
Joana Figueiredo ◽  
Jeremy J. Vaudo ◽  
James Hancock ◽  
Richard Rees ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Measurement Methods ◽  
Nursery Ground ◽  
The South ◽  
Free Swimming ◽  
Invasive Approach ◽  
Rhincodon Typus ◽  
Non Invasive ◽  
Whale Sharks ◽  
Conservation Concern

Whale sharks (Rhincodon typus) are an endangered species whose growth and reproductive biology are poorly understood. Given their conservation concern, estimating growth parameters, as traditionally derived from vertebral samples of dead animals, is challenging. We used a non-invasive approach to investigate growth parameters of whale sharks frequenting the South Ari Atoll, Maldives, by analysing repeat measurements of free-swimming sharks over a 10-year period. Total lengths of the sharks were estimated by three measurement methods. Visual estimates underestimated the sizes of large sharks, whereas laser and tape measurements yielded results that were similar to one another. The Maldives aggregation consisted of primarily male (91%) juvenile (total length=3.16–8.00m) sharks and sharks new to the area were significantly smaller than were returning sharks, which suggests that this site may constitute a secondary nursery ground. Estimates of von Bertalanffy (VBG) growth parameters for combined sexes (L∞=19.6m, k=0.021year–1) were calculated from 186 encounters with 44 sharks. For males, VBG parameters (L∞=18.1m, k=0.023year–1) were calculated from 177 encounters with 40 sharks and correspond to a male age at maturity of ~25 years and longevity of ~130 years. Differences between these estimates and those from other studies underscore the need for regional studies.

scholarly journals Regional movements of satellite‐tagged whale sharks Rhincodon typus in the Gulf of Aden

2021 ◽  
Author(s):  
Samantha Andrzejaczek ◽  
Michel Vély ◽  
Daniel Jouannet ◽  
David Rowat ◽  
Sabrina Fossette
Keyword(s):  
Gulf Of Aden ◽  
Rhincodon Typus ◽  
Whale Sharks

scholarly journals Host density predicts the probability of parasitism by avian brood parasites

2019 ◽  
Vol 374 (1769) ◽  
pp. 20180204 ◽  
Author(s):  
Iliana Medina ◽  
Naomi E. Langmore
Keyword(s):  
Spatial Distribution ◽  
Reproductive Success ◽  
Host Species ◽  
Field Data ◽  
Host Density ◽  
Brood Parasites ◽  
Parasitism Rates ◽  
Analyse Data ◽  
First Time ◽  
Determining Factor

The spatial distribution of hosts can be a determining factor in the reproductive success of parasites. Highly aggregated hosts may offer more opportunities for reproduction but can have better defences than isolated hosts. Here we connect macro- and micro-evolutionary processes to understand the link between host density and parasitism, using avian brood parasites as a model system. We analyse data across more than 200 host species using phylogenetic comparative analyses and quantify parasitism rate and host reproductive success in relation to spatial distribution using field data collected on one host species over 6 years. Our comparative analysis reveals that hosts occurring at intermediate densities are more likely to be parasitized than colonial or widely dispersed hosts. Correspondingly, our intraspecific field data show that individuals living at moderate densities experience higher parasitism rates than individuals at either low or high densities. Moreover, we show for the first time that the effect of host density on host reproductive success varies according to the intensity of parasitism; hosts have greater reproductive success when living at high densities if parasitism rates are high, but fare better at low densities when parasitism rates are low. We provide the first evidence of the trade-off between host density and parasitism at both macro- and micro-evolutionary scales in brood parasites. This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.

scholarly journals Diet of whale sharks Rhincodon typus inferred from stomach content and signature fatty acid analyses

2013 ◽  
Vol 493 ◽  
pp. 219-235 ◽  
Author(s):  
CA Rohner ◽  
LIE Couturier ◽  
AJ Richardson ◽  
SJ Pierce ◽  
CEM Prebble ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Stomach Content ◽  
Rhincodon Typus ◽  
Whale Sharks

scholarly journals Spatial and temporal patterns of nature-based tourism interactions with whale sharks (Rhincodon typus) at Ningaloo Reef, Western Australia

2014 ◽  
Vol 148 ◽  
pp. 109-119 ◽  
Author(s):  
Douglas J. Anderson ◽  
Halina T. Kobryn ◽  
Brad M. Norman ◽  
Lars Bejder ◽  
Julian A. Tyne ◽  
...  
Keyword(s):  
Western Australia ◽  
Temporal Patterns ◽  
Spatial And Temporal Patterns ◽  
Rhincodon Typus ◽  
Ningaloo Reef ◽  
Whale Sharks

scholarly journals Sizing and scarring of whale shark (Rhincodon typus Smith, 1828) in the Cenderawasih Bay National Park

2021 ◽  
Vol 21 (3) ◽  
pp. 199-213
Author(s):  
Yusup A Jentewo ◽  
Roni Bawole ◽  
Tresia S Tururaja ◽  
Mudjirahayu Mudjirahayu ◽  
Zeth Parinding ◽  
...  
Keyword(s):  
National Park ◽  
The Body ◽  
Whale Shark ◽  
Gill Slit ◽  
Rhincodon Typus ◽  
Photo Identification ◽  
Dorsal Fin ◽  
Total Length ◽  
Whale Sharks ◽  
Photo Collection

This study aims to determine the total length and scar condition of the body of whale sharks (Rhincodon typus) in Cendrawasih Bay National Park (TNTC), Papua-Indonesia. Photo-identification was used to identify individuals of the whale shark R. typus based on spot patterns behind the last gill slit of each individual. Photo-identification was also used to determine the scar of the whale shark. The total length of whale sharks were estimated based on the length of a snorkeller (assumed to be 1.6 m) swimming alongside the whale shark. We identified 21 individuals of R. typus. Of these 21 individuals, 14 were new sightings and seven were re-sightings that have been recorded in the previous photo collection database. R. typus ranged in size from 2 to 5 m total length (average 3.78 m, ±0,86, N= 21). Based on their size, all individuals of whale shark were categorized as juvenile. 52% of R. typus identified had scars and 38 % were not and 10% were unknown. The majority of whale sharks had amputation (12 individuals) and abrasion (7 individuals) scars. Scars occurred most often on the caudal fin and dorsal fin, five and four individuals respectively. This information is useful for understanding potential threats and designing better management programmes for R. typus conservation in TNTC.

Evidence of continued hunting of whale sharks Rhincodon typus in the Maldives

2009 ◽  
Vol 86 (3) ◽  
pp. 371-374 ◽  
Author(s):  
Morgan J. Riley ◽  
Adam Harman ◽  
Richard G. Rees
Keyword(s):  
Rhincodon Typus ◽  
Whale Sharks

scholarly journals St. Helena: An Important Reproductive Habitat for Whale Sharks (Rhincodon typus) in the Central South Atlantic

2020 ◽  
Vol 7 ◽  
Author(s):  
Cameron T. Perry ◽  
Elizabeth Clingham ◽  
D. Harry Webb ◽  
Rafael de la Parra ◽  
Simon J. Pierce ◽  
...  
Keyword(s):  
South Atlantic ◽  
Rhincodon Typus ◽  
Whale Sharks ◽  
St Helena ◽  
Central South
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