scholarly journals Oceanographic conditions associated with white shark (Carcharodon carcharias) habitat use along eastern Australia

2020 ◽  
Author(s):  
KA Lee ◽  
PA Butcher ◽  
RG Harcourt ◽  
TA Patterson ◽  
VM Peddemors ◽  
...  
Keyword(s):  
Habitat Use ◽  
White Shark ◽  
Carcharodon Carcharias ◽  
Eastern Australia ◽  
Oceanographic Conditions

scholarly journals Environmental conditions are poor predictors of immature white shark Carcharodon carcharias occurrences on coastal beaches of eastern Australia

2020 ◽  
Vol 653 ◽  
pp. 167-179
Author(s):  
JLY Spaet ◽  
A Manica ◽  
CP Brand ◽  
C Gallen ◽  
PA Butcher
Keyword(s):  
Environmental Conditions ◽  
Prey Availability ◽  
Statistical Significance ◽  
Time Of Day ◽  
White Shark ◽  
Additive Models ◽  
Large Sample Size ◽  
Lunar Phase ◽  
Carcharodon Carcharias ◽  
Eastern Australia

Understanding and predicting the distribution of organisms in heterogeneous environments is a fundamental ecological question and a requirement for sound management. To implement effective conservation strategies for white shark Carcharodon carcharias populations, it is imperative to define drivers of their movement and occurrence patterns and to protect critical habitats. Here, we acoustically tagged 444 immature white sharks and monitored their presence in relation to environmental factors over a 3 yr period (2016-2019) using an array of 21 iridium satellite-linked (VR4G) receivers spread along the coast of New South Wales, Australia. Results of generalized additive models showed that all tested predictors (month, time of day, water temperature, tidal height, swell height, lunar phase) had a significant effect on shark occurrence. However, collectively, these predictors only explained 1.8% of deviance, suggesting that statistical significance may be rooted in the large sample size rather than biological importance. On the other hand, receiver location, which captures geographic fidelity and local conditions not captured by the aforementioned environmental variables, explained a sizeable 17.3% of deviance. Sharks tracked in this study hence appear to be tolerant to episodic changes in environmental conditions, and movement patterns are likely related to currently undetermined, location-specific habitat characteristics or biological components, such as local currents, prey availability or competition. Importantly, we show that performance of VR4G receivers can be strongly affected by local environmental conditions, and provide an example of how a lack of range test controls can lead to misinterpretation and erroneous conclusions of acoustic detection data.

Spatiotemporal Patterns of White Shark (Carcharodon carcharias) Predation at the South Farallon Islands, California

Copeia ◽  
1992 ◽  
Vol 1992 (3) ◽  
pp. 680 ◽  
Author(s):  
A. Peter Klimley ◽  
Scot D. Anderson ◽  
Peter Pyle ◽  
R. P. Henderson
Keyword(s):  
White Shark ◽  
Spatiotemporal Patterns ◽  
The South ◽  
Carcharodon Carcharias

scholarly journals Variable response to electric shark deterrents in bull sharks, Carcharhinus leucas

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
A. R. G. Gauthier ◽  
E. Chateauminois ◽  
M. G. Hoarau ◽  
J. Gadenne ◽  
E. Hoarau ◽  
...  
Keyword(s):  
New Caledonia ◽  
White Shark ◽  
Mitigation Measures ◽  
Control Board ◽  
Variable Response ◽  
Carcharodon Carcharias ◽  
Behavioural Changes ◽  
Carcharhinus Leucas ◽  
Bull Shark ◽  
Over Time

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.

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