scholarly journals To Madagascar and back: long-distance, return migration across open ocean by a pregnant female bull shark Carcharhinus leucas

2015 ◽  
Vol 87 (6) ◽  
pp. 1313-1321 ◽  
Author(s):  
J. S. E. Lea ◽  
N. E. Humphries ◽  
C. R. Clarke ◽  
D. W. Sims

2014 ◽  
Vol 2 ◽  
pp. 300-314 ◽  
Author(s):  
Craig P. O’Connell ◽  
Saang-Yoon Hyun ◽  
Chris B. Rillahan ◽  
Pingguo He


2017 ◽  
Vol 74 (2) ◽  
pp. 216-227 ◽  
Author(s):  
Clément Trystram ◽  
Karyne M. Rogers ◽  
Marc Soria ◽  
Sébastien Jaquemet

Stomach contents and stable carbon and nitrogen isotope analyses (δ13C and δ15N) were used to investigate the trophic ecology of two apex predators, tiger sharks (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas), from Reunion Island to describe their dietary habits at both the population and individual levels. In this oceanic island, the tiger and bull sharks were more piscivorous and teutophagous than noted in previous research from other localities. The δ13C values suggested that bull sharks depended on more neritic organic matter sources than tiger sharks, confirming a coastal habitat preference for bull sharks. Moreover, the total length of the bull shark influenced δ13C values, with smaller individuals being more coastal than larger individuals. All indicators suggest that there is a higher degree of similarity between individual tiger sharks compared with the more heterogeneous bull shark population, which is composed of individuals who specialize on different prey. These results suggest that the two species have different functions in these coastal habitats, and thus, they must be considered independently in terms of conservation and management.



2018 ◽  
Vol 59 (1) ◽  
pp. 48-60 ◽  
Author(s):  
P S Segre ◽  
D E Cade ◽  
J Calambokidis ◽  
F E Fish ◽  
A S Friedlaender ◽  
...  

Abstract Blue whales are often characterized as highly stable, open-ocean swimmers who sacrifice maneuverability for long-distance cruising performance. However, recent studies have revealed that blue whales actually exhibit surprisingly complex underwater behaviors, yet little is known about the performance and control of these maneuvers. Here, we use multi-sensor biologgers equipped with cameras to quantify the locomotor dynamics and the movement of the control surfaces used by foraging blue whales. Our results revealed that simple maneuvers (rolls, turns, and pitch changes) are performed using distinct combinations of control and power provided by the flippers, the flukes, and bending of the body, while complex trajectories are structured by combining sequences of simple maneuvers. Furthermore, blue whales improve their turning performance by using complex banked turns to take advantage of their substantial dorso-ventral flexibility. These results illustrate the important role body flexibility plays in enhancing control and performance of maneuvers, even in the largest of animals. The use of the body to supplement the performance of the hydrodynamically active surfaces may represent a new mechanism in the control of aquatic locomotion.





2020 ◽  
Vol 10 (1) ◽  
Author(s):  
A. R. G. Gauthier ◽  
E. Chateauminois ◽  
M. G. Hoarau ◽  
J. Gadenne ◽  
E. Hoarau ◽  
...  

Abstract Although relatively rare, human-shark interactions and sharks bites are increasing globally, which has led to the development of various mitigation measures. Electric shark deterrents (ESDs) have, so far, been the most effective personal deterrents, but have only been scientifically tested on one of the species most frequently responsible for shark bites, i.e. white shark (Carcharodon carcharias). We tested the effectiveness of five ESDs (E-Shark Force, NoShark, Rpela v2, Freedom + Surf, Freedom + Surf—Shortboard) on bull sharks, Carcharhinus leucas, over a period of 21 days in September 2019, in New Caledonia. Standardised bait was attached 30 cm below an experimental board that had an active ESD for up to 15 min, or until a bull shark touched the bait or the board. We compared the numbers of baits taken, numbers of passes and reactions around the board, as well as the distance between the sharks and the board among ESDs and against a control board with bait and no active ESD. The Freedom + Surf was the most effective ESD, reducing the amounts of baits taken by 42.3%, while the Rpela v2 and Freedom + Surf—Shortboard also significantly reduced the number of baits taken by 16.5% and 16.2% respectively. Mean distance between sharks and the bait was not affected by the ESDs, but the number of approaches and the proportion of reactions were both significantly higher when the Freedom + Surf was active compared to other ESDs. The effectiveness of all ESDs decreased over time, with the likelihood of the bait being taken increasing and the number of approaches and distance between sharks and the bait decreasing. Our findings show that the ability of ESDs to deter bull shark varies between products, with the Freedom + Surf resulting in the most behavioural changes, followed by the Rpela v2 and Freedom + Surf—Shortboard. However, none of the products tested completely stopped sharks from taking the bait.



Copeia ◽  
1972 ◽  
Vol 1972 (3) ◽  
pp. 601 ◽  
Author(s):  
Thomas B. Thorson


1986 ◽  
Vol 43 (11) ◽  
pp. 2206-2211 ◽  
Author(s):  
D. S. Pezzack ◽  
D. R. Duggan

In the Browns Bank region of the Scotian Shelf between June 1982 and December 1983, 6285 tagged lobsters (Homarus americanus) were released. Of the 2486 lobsters recaptured, 361 were recaptured more than once. Eight lobsters released in late May to mid-July were recaptured the following spring and summer, with at least one intervening recapture in the fall–winter period. Five of the eight lobsters showed homing tendencies. Two lobsters made long-distance (> 200 km) return migrations, three made short (50–100 km) return migrations, and three moved long distances but did not return. One lobster at large 6 mo and four at large 22–34 mo made long-distance return migrations, moving over 200 km and returning to within 9–42 km of the initial release site. The data indicate that some lobsters undertake long-distance return migration, which returns the lobsters to specific sections of the Shelf.



2019 ◽  
Vol 22 ◽  
pp. 171-176
Author(s):  
Muhammad Iqbal ◽  
Elisa Nurnawati ◽  
Arum Setiawan ◽  
Zulkifli Dahlan ◽  
Indra Yustian

Two specimens (c.700 mm) of bull sharks Carcharhinus leucas (Müller & Henle, 1839) were caught and photographed by fishermen using trammel net on 29 September and 1 October 2017 in Musi River, South Sumatra province, Indonesia. These photos are considered as second record after 20 years (1997-2017), and first confirm inland record for Sumatra. Photographic records indicate specimens of C. leucas found in Musi River basin recorded about 75 km inland, and apparently very young juveniles. Further study and monitoring is needed to asses the possibility of the importance of Musi River basin as nursery area of C. leucas.



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