ORCID Profile
0000-0002-9901-3279
Current Organisations
ETH Zurich
,
University of Zurich
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Publisher: PeerJ
Date: 04-05-2017
DOI: 10.7717/PEERJ.3271
Abstract: Eight whale sharks tagged with pop-up satellite archival tags off the Gulf of California, Mexico, were tracked for periods of 14–134 days. Five of these sharks were adults, with four females visually assessed to be pregnant. At least for the periods they were tracked, juveniles remained in the Gulf of California while adults moved offshore into the eastern Pacific Ocean. We propose that parturition occurs in these offshore waters. Excluding two juveniles that remained in the shallow tagging area for the duration of tracking, all sharks spent 65 ± 20.7% (SD) of their time near the surface, even over deep water, often in association with frontal zones characterized by cool-water upwelling. While these six sharks all made es into the meso- or bathypelagic zones, with two sharks reaching the maximum depth recordable by the tags (1285.8 m), time spent at these depths represented a small proportion of the overall tracks. Most deep es (72.7%) took place during the day, particularly during the early morning and late afternoon. Pronounced habitat differences by ontogenetic stage suggest that adult whale sharks are less likely to frequent coastal waters after the onset of maturity.
Publisher: CSIRO Publishing
Date: 2023
DOI: 10.1071/PC23009
Publisher: Elsevier BV
Date: 08-2018
Publisher: Elsevier BV
Date: 02-2019
Publisher: Informa UK Limited
Date: 16-06-2021
Publisher: Public Library of Science (PLoS)
Date: 13-03-2013
Publisher: Elsevier BV
Date: 11-2017
Publisher: Public Library of Science (PLoS)
Date: 23-01-2014
Publisher: Hindawi Limited
Date: 2008
DOI: 10.1155/2008/107576
Abstract: 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.
Publisher: Wiley
Date: 07-09-2017
DOI: 10.1111/ACV.12370
Publisher: Springer Science and Business Media LLC
Date: 18-01-2018
DOI: 10.1038/S41559-017-0432-Z
Abstract: Sharks are a erse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain in iduals that forage within additional isotopically erse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.
Publisher: Frontiers Media SA
Date: 12-06-2020
Publisher: Wiley
Date: 02-2023
DOI: 10.1002/ECE3.9837
Abstract: The Bull Shark ( Carcharhinus leucas ) faces varying levels of exploitation around the world due to its coastal distribution. Information regarding population connectivity is crucial to evaluate its conservation status and local fishing impacts. In this study, we s led 922 putative Bull Sharks from 19 locations in the first global assessment of population structure of this cosmopolitan species. Using a recently developed DNA‐capture approach (DArTcap), s les were genotyped for 3400 nuclear markers. Additionally, full mitochondrial genomes of 384 Indo‐Pacific s les were sequenced. Reproductive isolation was found between and across ocean basins (eastern Pacific, western Atlantic, eastern Atlantic, Indo‐West Pacific) with distinct island populations in Japan and Fiji. Bull Sharks appear to maintain gene flow using shallow coastal waters as dispersal corridors, whereas large oceanic distances and historical land‐bridges act as barriers. Females tend to return to the same area for reproduction, making them more susceptible to local threats and an important focus for management actions. Given these behaviors, the exploitation of Bull Sharks from insular populations, such as Japan and Fiji, may instigate local decline that cannot readily be replenished by immigration, which can in turn affect ecosystem dynamics and functions. These data also supported the development of a genetic panel to ascertain the population of origin, which will be useful in monitoring the trade of fisheries products and assessing population‐level impacts of this harvest.
Publisher: Wiley
Date: 13-06-2019
DOI: 10.1002/ECE3.5304
Publisher: Elsevier BV
Date: 05-2017
No related grants have been discovered for Juerg Brunnschweiler.