The use of permanent magnets to reduce elasmobranch encounter with a simulated beach net. 1. The bull shark (Carcharhinus leucas)

O’Connell, Craig P.; Hyun, Saang Yoon; Gruber, Samuel H.; O’Connell, Timmy; Johnson, Grant; Grudecki, Katie; He, Pingguo

doi:10.1016/j.ocecoaman.2013.12.012

Cited by 15 publications

(19 citation statements)

References 30 publications

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“…Comparable to previous studies, C. leucas behavior was significantly altered in relation to both the magnetic and procedural control regions (O'Connell et al, 2013b(O'Connell et al, , 2014. In O'Connell et al (2014), white sharks (Carcharodon carcharias) never entered through procedural control and magnetic regions of the Sharksafe barrier.…”

Section: Bull Sharkscontrasting

confidence: 67%

“…Similarly, in O'Connell et al (2013b), C. leucas were observed to swim around magnetic and procedural control regions of a barrier; however unlike the present study and O'Connell et al (2014), entrance behaviors through procedural control and magnetically-treated barrier regions did occur. In the present study and in O'Connell et al (2014), there were two and three rows of alternating columns, respectively, whereas in the previous study (O'Connell et al, 2013b), only one row of columns was deployed. Therefore, the added visual stimulus provided by increased column quantity may have been sufficient to elicit these behavioral differences and may have maximized overall barrier effectiveness.…”

Section: Bull Sharkscontrasting

confidence: 52%

“…Secondly, inter-experimental differences in C. leucas behavior towards barrier structures may be a result of inter-column spacing variations. In O'Connell et al (2013b), inter-column spacing was 1.5 m whereas inter-column spacing was 0.63 m in the present study when both alternating rows are considered. This reduction may be an influential factor since visual stimuli and magnetic field density were maximized.…”

Section: Bull Sharksmentioning

confidence: 63%

“…Thirdly, due to varying levels of conspecifics and heterospecifics, it was hypothesized that situations arising from increased intra-and inter-specific competition (e.g. Robbins et al, 2011;O'Connell et al, 2013b) may result in significant reductions in the exclusion capabilities of the Sharksafe barrier on interacting C. leucas. The barrier was composed of four equal-sized (7 × 3 m) regions, two controls-unmanipulated areas, one procedural control, and one magnetic region.…”

Section: Introductionmentioning

confidence: 99%

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Bull shark ( Carcharhinus leucas ) exclusion properties of the sharksafe barrier and behavioral validation using the ARIS technology

O’Connell

Hyun

Rillahan

et al. 2014

Global Ecology and Conservation

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a b s t r a c tMagnetic deterrents have recently been employed to assess their ability to reduce elasmobranch mortality in beach nets. With previous studies exhibiting promise, the present study examined the ability of a magnetic barrier technology, known as the Sharksafe Barrier, to exclude bull sharks (Carcharhinus leucas) from bait, and how behavioral interactions may change with variations in environmental and biological factors. Generalized linear mixed model analyses based on 114, 30-min trials illustrate that all interacting C. leucas were successfully excluded from baited procedural control and magnetic regions (i.e. zero entrances through either region). Avoidance and pass around frequencies significantly differed from the control region and were based on situational context. To enhance behavioral analysis techniques, an Adaptive Resolution Imaging Sonar (ARIS) was employed which revealed that C. leucas distance from and swim speed associated with the magnetic barrier region were significantly greater than those associated with the procedural control region. This study demonstrates the Sharksafe barrier's effectiveness in excluding C. leucas from baited regions, regardless of variations in biological and/or environmental parameters. While other bather protection systems (e.g. beach nets and drumlines) continue to be used, this study exhibits promise that the Sharksafe barrier can be an eco-friendly alternative to beach nets.

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Section: Bull Sharkscontrasting

confidence: 67%

Section: Bull Sharkscontrasting

confidence: 52%

Section: Bull Sharksmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

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Bull shark ( Carcharhinus leucas ) exclusion properties of the sharksafe barrier and behavioral validation using the ARIS technology

O’Connell

Hyun

Rillahan

et al. 2014

Global Ecology and Conservation

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“…Nevertheless, several factors are to be considered. (i) Results from the literature are mainly based upon laboratory experiments, and/or in situ experiments more or less remote from the real conditions of a professional fishing fleet (Stoner and Kaimmer, 2008;Tallack and Mandelman, 2009;O'Connell et al, 2011aO'Connell et al, , 2014aRobbins et al, 2011). (ii) Clearly, the non-congruence of deterrent effects noted by previous authors is species-dependent (Hutchinson et al, 2012); for example, some authors showed that while EPM are ineffective with blue shark and shortfin mako, they can be effective for other species (Appendix A).…”

Section: Experiments Under Real Fishing Conditionsmentioning

confidence: 99%

Hooks equipped with magnets can increase catches of blue shark (Prionace glauca) by longline fishery

et al. 2015

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Evaluating the effects of a SharkSafe Barrier™ shoreline deployment on bull shark (Carcharhinus leucas) behaviour

O’Connell

Gressle²,

Crews

et al. 2021

Aquatic Conservation

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1. Beach nets and drumlines are lethal devices that are used to minimize the interaction between potentially dangerous sharks and beachgoers. Mortality to these large shark species as a result of these lethal measures has led to the development of non-invasive technologies that may minimize the risks of rare encounters with beachgoers while simultaneously protecting vulnerable sharks and other marine species.2. One such technology is the SharkSafe Barrier™, which uses visual and magnetic stimuli to non-invasively deter sharks from a designated area. Previous experiments using this technology were performed on a small scale (e.g. 13 m Â 13 m), with an attempt made to extrapolate the results to a larger scale application without actual large-scale deployments and experimentation.3. The present study examined whether a large-scale SharkSafe Barrier™ shoreline deployment could successfully exclude the bull shark (Carcharhinus leucas) from acoustic and olfactory cues and evaluated whether the technology could serve as a less invasive replacement to current culling practices.4. Generalized linear mixed-model analyses based on 59 trials illustrate that C. leucas swimming behaviour (i.e. avoidances, entrances, and pass arounds) significantly differed between the control (i.e. unmanipulated area) and the experimental (i.e. SharkSafe Barrier™) regions. Unlike previous small-scale experiments, 10 of 16 sharks repeatedly penetrated the barrier and swam in an accelerated manner once within the experimental barrier region.5. The present findings raise concerns that the size of the previous experimental areas may have been insufficient to provide a realistic representation of barrier efficacy for large-scale deployments. With continued shark-culling measures in various locations, a non-invasive and eco-friendly alternative is needed, but substantial modifications to the current Sharksafe barrier design or an entirely new eco-friendly approach are needed as the barrier in its present state does not reliably deter large and potentially dangerous sharks from a large-scale area.

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The use of permanent magnets to reduce elasmobranch encounter with a simulated beach net. 1. The bull shark (Carcharhinus leucas)

Cited by 15 publications

References 30 publications

Bull shark ( Carcharhinus leucas ) exclusion properties of the sharksafe barrier and behavioral validation using the ARIS technology

Bull shark ( Carcharhinus leucas ) exclusion properties of the sharksafe barrier and behavioral validation using the ARIS technology

Hooks equipped with magnets can increase catches of blue shark (Prionace glauca) by longline fishery

Evaluating the effects of a SharkSafe Barrier™ shoreline deployment on bull shark (Carcharhinus leucas) behaviour

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