Studying Shark Attacks

A large number of man-made tidal swimming pools (two examples are shown in Figure 1) exist along the South African coast. They are usually situated on rocky outcrops in the close vicinity of popular sandy bathing beaches to provide protected bathing conditions in these areas mainly for children and elderly people. Some tidal pools, especially along rocky coast, provide the only safe bathing facilities. Besides affording protection against waves and surfzone currents the pools provide protection from sharks. A large number of tidal pools were built during the early 1950s along the Natal South Coast after the occurrence of a relatively large number of shark attacks on bathers on that coast. The semi-diurnal tide with a range of about 1,5 m along the South African coast makes it possible for pools to be built such that water replenishment can occur during every high-water (approximately every 12 hours) during both neap and spring tide periods. Presently, there exists a great need for more tidal pools as part of the demand for more recreational facilities along the South African coast. However, no information on design criteria could be found in the literature.

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Predicting fatalities among shark attacks: comparison of classifiers

IAES International Journal of Artificial Intelligence (IJ-AI) ◽

10.11591/ijai.v8.i4.pp360-366 ◽

2019 ◽

Vol 8 (4) ◽

pp. 360 ◽

Cited By ~ 1

Author(s):

Lim Mei Shi ◽

Aida Mustapha ◽

Yana Mazwin Mohmad Hassim

Keyword(s):

Support Vector Machines ◽

Performance Measurement ◽

Support Vector ◽

Error Measure ◽

Accuracy And Precision ◽

Vector Machines ◽

Shark Attacks ◽

Probabilistic Error

<span lang="EN-US">This paper presents the comparisons of different classifiers on predicting Shark attack fatalities. In this study, we are comparing two classifiers which are Support vector machines(SVMs) and Bayes Point Machines(BPMs) on Shark attacks dataset. The comparison of the classifiers were based on the accuracy, recall, precision and F1-score as the performance measurement. The results obtained from this study showed that BPMs predicted the fatality of shack attack victim experiment with higher accuracy and precision than the SVMs because BPMs have “average” identifier which can minimize the probabilistic error measure. From this experiment, it is concluded that BPMs are more suitable in predicting fatality of shark attack victim as BPMs is an improvement of SVMs.</span>

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The Shark Attack Problem Revisited: MCMC with the Metropolis Algorithm

Bayesian Statistics for Beginners ◽

10.1093/oso/9780198841296.003.0013 ◽

2019 ◽

pp. 193-211

Author(s):

Therese M. Donovan ◽

Ruth M. Mickey

Keyword(s):

Monte Carlo ◽

Parameter Estimation ◽

Markov Chain ◽

Posterior Distribution ◽

Metropolis Algorithm ◽

Tuning Parameter ◽

The Mean ◽

Shark Attacks ◽

Mcmc Approach

In this chapter, the “Shark Attack Problem” (Chapter 11) is revisited. Markov Chain Monte Carlo (MCMC) is introduced as another way to determine a posterior distribution of λ‎, the mean number of shark attacks per year. The MCMC approach is so versatile that it can be used to solve almost any kind of parameter estimation problem. The chapter highlights the Metropolis algorithm in detail and illustrates its application, step by step, for the “Shark Attack Problem.” The posterior distribution generated in Chapter 11 using the gamma-Poisson conjugate is compared with the MCMC posterior distribution to show how successful the MCMC method can be. By the end of the chapter, the reader should also understand the following concepts: tuning parameter, MCMC inference, traceplot, and moment matching.

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Shark control: experimental fishing with baited drumlines

Marine and Freshwater Research ◽

10.1071/mf98026 ◽

1998 ◽

Vol 49 (7) ◽

pp. 653 ◽

Cited By ~ 16

Author(s):

S. F. J. Dudley ◽

R. C. Haestier ◽

K. R. Cox ◽

M. Murray

Keyword(s):

Optimal Solution ◽

Control Programme ◽

Shark Species ◽

Gill Nets ◽

Carcharhinus Leucas ◽

Local Reduction ◽

Shark Attacks ◽

By Catch ◽

Catch Rates ◽

Physical Environmental Factors

Protective gill-nets (shark nets) have been successful in reducing the frequency of shark attacks on the coast of KwaZulu-Natal (KZN), South Africa, since 1952. This is achieved primarily through a local reduction in numbers of large sharks. Yet the nets are non-selective in terms of shark species caught and take a by-catch of dolphins, sea turtles, batoids and teleosts. Baited lines, or drumlines, as used in the Queensland shark control programme, were tested as possible alternatives to gill-nets. They demonstrated greater species selectivity for sharks and also a reduced by-catch of non-shark animals. The shark catch included the three species responsible for most shark attacks on the KZN coast, Carcharhinus leucas, Galeocerdo cuvier and Carcharodon carcharias. The probability of the bait being scavenged, or a shark being caught, was modelled in relation to a number of physical environmental factors. Although there was insufficient variability in the effort data for a quantitative comparison of catch rates between nets and drumlines, the results suggested that an optimal solution may be to deploy a combination of nets and drumlines.

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A REVIEW OF SHARK ATTACKS IN AUSTRALIAN WATERS SINCE 1919

The Medical Journal of Australia ◽

10.5694/j.1326-5377.1950.tb106830.x ◽

1950 ◽

Vol 2 (19) ◽

pp. 680-687 ◽

Cited By ~ 7

Author(s):

V. M. Coppleson

Keyword(s):

Shark Attacks

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Shark attacks on the Transkei Coast of South Africa: A case report

African Journal of Primary Health Care & Family Medicine ◽

10.4102/phcfm.v1i1.48 ◽

2009 ◽

Vol 1 (1) ◽

Author(s):

Banwari L. Meel

Keyword(s):

South Africa ◽

Case Report ◽

Femoral Artery ◽

Case History ◽

Lower Limb ◽

Safety Measures ◽

Legal Implications ◽

Shark Attacks ◽

Physical Findings ◽

Cut Surface

Shark attacks are relatively uncommon, but can be fatal in nature. It is diffcult to understand the behaviour and motivation of this predator.In the summer of 1998 a 28-year-old male, who was an experienced, enthusiastic surfer, was attacked by a shark near Hole-in-the Wall on the Wild Coast in the Transkei region of South Africa. His right lower limb was severed, with profuse bleeding from the torn femoral artery. Sharp broken ends of the femur and torn muscles were noticed at autopsy. The viscera were extremely pale. The lungs, in addition to being pale, were shrunken and dry, and there was no fluid that oozed out upon squeezing the cut surface. The case history, physical findings, and medico-legal implications are discussed in this report. Preventive and safety measures related to shark attacks are suggested.

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Sharks shape the geometry of a selfish seal herd: experimental evidence from seal decoys

Biology Letters ◽

10.1098/rsbl.2009.0628 ◽

2009 ◽

Vol 6 (1) ◽

pp. 48-50 ◽

Cited By ~ 29

Author(s):

Alta De Vos ◽

M. Justin O'Riain

Keyword(s):

Experimental Evidence ◽

Predation Risk ◽

Prey Species ◽

Group Formation ◽

Predator Prey ◽

Selfish Herd ◽

Fur Seal ◽

Cape Fur Seal ◽

Shark Attacks ◽

Proportional Reduction

Many animals respond to predation risk by forming groups. Evolutionary explanations for group formation in previously ungrouped, but loosely associated prey have typically evoked the selfish herd hypothesis. However, despite over 600 studies across a diverse array of taxa, the critical assumptions of this hypothesis have remained collectively untested, owing to several confounding problems in real predator–prey systems. To solve this, we manipulated the domains of danger of Cape fur seal ( Arctocephalus pusillus pusillus ) decoys to provide evidence that a selfish reduction in a seals' domain of danger results in a proportional reduction in its predation risk from ambush shark attacks. This behaviour confers a survival advantage to individual seals within a group and explains the evolution of selfish herds in a prey species. These findings empirically elevate Hamilton's selfish herd hypothesis to more than a ‘theoretical curiosity’.

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Shark attacks: Is it safe to go back in the water?

Science ◽

10.1126/science.aac8881 ◽

2015 ◽

Author(s):

Hanae Armitage

Keyword(s):

Shark Attacks

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Men in Grey Suits: Shark Activity and Congestion of the Surfing Commons

Sustainability ◽

10.3390/su11113114 ◽

2019 ◽

Vol 11 (11) ◽

pp. 3114

Author(s):

Franklin G. Mixon ◽

Chandini Sankaran

Keyword(s):

Baseline Level ◽

White Shark ◽

Ordered Probit ◽

Great White Shark ◽

The Commons ◽

Key Variables ◽

The Common ◽

Shark Attacks ◽

Using Data ◽

Ordered Probit Models

This study extends recent research on informal property rights at surf breaks by exploring the process through which nature, by establishing conditions conducive (or not) to the presence of sharks, shapes the baseline level of exploitation by surfers of the common-pool resource represented by surf breaks. Since 1980, there have been nine fatal shark attacks off the coast of California, and in all nine cases the great white shark was the offending species. Given this inherent danger, the presence of large sharks mitigates, at least to some degree, the tendency toward the ‘tragedy of the commons’ in the case of surf breaks. Using data on surf break congestion, surf break quality, shark activity, and other key variables from 144 surf breaks in California, empirical results from OLS and ordered probit models presented in this study indicate that surf breaks in California that are associated with the highest levels of shark activity tend to be less congested, perhaps by as much as 28%, than their counterparts that are visited less often by sharks.

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