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Hunting patterns and geographic profiling of white shark predation
Journal of Zoology
Abstract
Predators can play important roles in structuring their communities through top-down effects on the distribution and abundance of their prey. Sharks are top predators in many marine communities, yet few studies have quantified those factors influencing their distribution and hunting behaviour. Here, we use location data from 340 predatory interactions between white sharks Carcharodon carcharias (Linnaeus), and Cape fur seals Arctocephalus pusillus pusillus (Schreber), data on associated environmental factors, and spatial analysis, including a novel application of geographic profiling – a tool originally developed to analyse serial crime – to investigate spatial patterns of shark attack and search behaviour at Seal Island in False Bay, South Africa. We found that spatial patterns of shark predation at this site are nonrandom. Sharks appear to possess a well-defined search base or anchor point, located 100 m seaward of the seal's primary island entry–exit point. This location is not where chances of intercepting seals are greatest and we propose it may represent a balance among prey detection, capture rates, and competition. Smaller sharks exhibit more dispersed prey search patterns and have lower predatory success rates than larger conspecifics, suggesting possible refinement of hunting strategy with experience or competitive exclusion of smaller sharks from the most profitable hunting locations. As many of the features of this system will be common to other instances of foraging, our conclusions and approach employed may have implications and applications for understanding how large predators hunt and for studying other predator–prey systems.
... Particularly hot or cold years could change the estimations in this model, as could behavioral shifts in response to changing salinity, which may affect food conversion or prey selection [56,72,84,97,112]. Predation risk and competition can all influence the behavior and energy requirements of fish but were not fully accounted for in this model [116,117]. It would be expected that predation avoidance involves increased activity, perhaps not contemplated in our activity parameter [116]. ...
... Predation risk and competition can all influence the behavior and energy requirements of fish but were not fully accounted for in this model [116,117]. It would be expected that predation avoidance involves increased activity, perhaps not contemplated in our activity parameter [116]. Competition may result in reduced consumption when another species outcompetes M. schmitti in resource allocation [117]. ...
... (2) Incorporation of ecological factors: The model can be expanded to consider additional ecological factors that influence the energy requirements and behavior of M. schmitti [74,114]. Factors such as predation risk, competition, and habitat preferences can significantly impact the energy dynamics of the species [116,117]. Incorporating these factors, when sufficient data become available, would improve the model's ecological realism and predictive power. (3) Long-term monitoring and data collection: Long-term monitoring of M. schmitti populations, including growth rates, prey availability, and environmental conditions, would provide valuable data for validating and updating the model [115,119]. ...
Bioenergetic models are tools that allow the evaluation of the effect of environmental variables on fish growth. Successful implementation of this approach has been achieved in a few elasmobranch species. Our objective was to develop a bioenergetic model for Mustelus schmitti. The model developed showed a good fit to the field data available and accurately described the growth of this species. The practical example developed in this study provides novel population estimates of prey consumption and daily ration for the species. Results also indicate that this species would be susceptible to the effects of climate change. In the simulated climate change scenarios, the energy budget of M. schmitti was significantly altered, with increased food consumption and impaired growth. While there exists a number of limitations for the model developed in this article, namely its limitation to immature individuals, and its restricted temperature model, it provides an important tool for the management of this and other shark populations under heavy exploitation.
... During these two optimal scotopic periods, the ambient light levels are too low for the prey to distinguish an ambushing predator below but sufficient for a white shark to identify the silhouette of its prey at the surface [69]. Intraspecific competition and/ or less accrued hunting experience [70] are likely to force the smaller white sharks to forage for longer and outside these crepuscular, optimal, hunting periods. While the hunting behaviour of smaller white sharks changes spatially to suboptimal conditions in False Bay [70] and at the Farallon Islands [36] the shift towards suboptimal conditions appears to be temporal in Mossel Bay. ...
... Intraspecific competition and/ or less accrued hunting experience [70] are likely to force the smaller white sharks to forage for longer and outside these crepuscular, optimal, hunting periods. While the hunting behaviour of smaller white sharks changes spatially to suboptimal conditions in False Bay [70] and at the Farallon Islands [36] the shift towards suboptimal conditions appears to be temporal in Mossel Bay. This is possibly because of the small size of its pinniped colony: different behavioural patterns related to different size in the islands with pinniped colonies was also observed in two other white shark aggregations, such as Guadalupe and South Farallon Islands [48]. ...
... Being an obligate ram ventilator [67] a white shark is expected to either actively search for mates and or food (patrolling) or travel between important resourcerich areas [70]. A possible explanation for the main movement pattern found over estuary-related reef structures may be related to its slower nature, possibly to the need to reduce swimming-related energy costs at times, while maintaining the higher metabolic requirements of a regional endothermic species [32,98]. ...
Background
Little is known about the fine-scale behavioural choices white sharks make. The assessment of movement at high spatio-temporal resolution can improve our understanding of behavioural patterns. Active acoustic telemetry was used along a coastal seascape of South Africa to investigate the movement-patterns of 19 white sharks tracked for 877 h within habitats known to host different prey types.
Results
A three-state hidden Markov model showed higher ontogenetic variability in the movements of white sharks around estuary-related coastal reef systems compared to around a pinniped colony. Our results further suggest white sharks (1) use the same searching strategy in areas where either pinnipeds or fishes are present; (2) occupy sub-tidal reef habitats possibly for either conserving energy or recovering energy spent hunting, and (3) travel directly between the other two states.
Conclusions
White sharks appear not to simply roam coastal habitats, but rather adopt specific temporally optimized behaviours associated with distinct habitat features. The related behaviours are likely the result of a balance among ontogenetic experience, trophic niche, and energetics, aimed at maximizing the use of temporally and spatially heterogeneous environments and resources. The possible implications for the future conservation of white sharks in coastal areas are discussed, with particular attention to South Africa’s present conservation and management challenges.
... 60 000 Cape fur seals (Fig. 1). White sharks Carcharodon carcharias aggregate here during the winter to actively hunt Cape fur seals Arctocephalus pusillus pusillus when they leave and return from Seal Island (Martin et al. 2005(Martin et al. , 2009). The seals forage in False Bay or up to 30 km (or greater) offshore, returning to Seal Island at irregular intervals (Martin et al. 2005. ...
... Attacks are concentrated on the southern side of the island, close to shore (within 2 km). Thus, by positioning at the south end of Seal Island where most predatory activity occurs, a single vessel can survey at least 270° uninterrupted to a distance of at least 3.5 km (Hammerschlag et al. 2006, Martin et al. 2009). Observations were made at Seal Island each month, by 1 boat, between 1999 and 2013. ...
... Given the high energetic requirements of a predation attempt, white sharks are observed to launch attacks on seals only when environmental conditions are optimal for success, increasing efficiency of energy expenditure (Hammerschlag et al. 2006). These conditions include targeting seals during a specific range of low-light levels as well as staging attacks from identifiable deep-water locations around the Island that provide sharks with a visual and tactical advantage over seals (Hammerschlag et al. 2006, Martin et al. 2009). ...
Understanding potential responses of aquatic animals to climate variability is important, given the wide-ranging implications of current and future climatic change scenarios. Here, we used long-term data from natural predator?prey interactions between white sharks Carcharodon carcharias and Cape fur seals Arctocephalus pusillus pusillus in False Bay, South Africa, paired with environmental monitoring to examine potential relationships between temperature variability and shark predation rates on seals. Based on generalized linear modelling of a dataset of 941 shark attacks on seals collected over 15 years (1999?2013) during the austral winter (May?September) season, we found water temperature was included as a significant predictor of daily and monthly variability in predation rates. However, the signal of temporal variability over the season emerged as a more predominant predictor. Moreover, inter-annual variability in predation rate appeared linked to other environmental factors (wind, water visibility, and the occurrence of El Niño and La Niña events) rather than water temperature. These data suggest that water temperatures on an intra-annual scale might contribute to predation patterns in white sharks either directly or indirectly (e.g. due to associated changes in prey availability), but do not implicate water temperature as a primary driver in this scenario, or at an interannual scale. It is possible that (1) the metabolic demand of white sharks may be modulated against temperature variability by their partially endothermic nature, and (2) the predation patterns of white sharks on seals are the result of a complex interplay between ambient physical conditions and broader oceanographic, biological, and ecological factors.
... 60 000 Cape fur seals (Fig. 1). White sharks Carcharodon carcharias aggregate here during the winter to actively hunt Cape fur seals Arctocephalus pusillus pusillus when they leave and return from Seal Island (Martin et al. 2005(Martin et al. , 2009). The seals forage in False Bay or up to 30 km (or greater) offshore, returning to Seal Island at irregular intervals (Martin et al. 2005. ...
... Attacks are concentrated on the southern side of the island, close to shore (within 2 km). Thus, by positioning at the south end of Seal Island where most predatory activity occurs, a single vessel can survey at least 270° uninterrupted to a distance of at least 3.5 km (Hammerschlag et al. 2006, Martin et al. 2009). Observations were made at Seal Island each month, by 1 boat, between 1999 and 2013. ...
... Given the high energetic requirements of a predation attempt, white sharks are observed to launch attacks on seals only when environmental conditions are optimal for success, increasing efficiency of energy expenditure (Hammerschlag et al. 2006). These conditions include targeting seals during a specific range of low-light levels as well as staging attacks from identifiable deep-water locations around the Island that provide sharks with a visual and tactical advantage over seals (Hammerschlag et al. 2006, Martin et al. 2009). ...
Understanding potential responses of aquatic animals to climate variability is important given the wide-ranging implications of current and future climatic change scenarios. Here, we used long-term data from natural predator–prey interactions between white sharks Carcharodon carcharias and Cape fur seals Arctocephalus pusillus pusillus in False Bay, South Africa, paired with environmental monitoring to examine potential relationships between temperature variability and shark predation rates on seals. Based on generalized linear modelling of a dataset of 941 shark attacks on seals collected over 15 years (1999–2013) during the winter (May–September) season, we found water temperature was included as a significant predictor of daily and monthly variability in predation rates. However, the signal of temporal variability over the season emerged as a more predominant predictor. Moreover, inter-annual variability in predation rate appeared linked to other environmental factors (wind, water visibility, and the occurrence of El Niño and La Niña events) rather than water temperature. These data suggest that water temperatures on an intra-annual scale might contribute to predation patterns in white sharks either directly or indirectly (e.g. due to associated changes in prey availability), but do not implicate water temperature as a primary driver in this scenario or at an interannual scale. It is possible that (1) metabolic demand of white sharks may be modulated against temperature variability by their partially endothermic nature, and (2) predation patterns of white sharks on seals are the result of a complex interplay between ambient physical conditions, and broader oceanographic, biological, and ecological factors.
... Other observations of prey species, along with telemetry data on swim speeds and long periods of residency of white sharks at the Carpinteria aggregation site (Anderson et al. 2021b(Anderson et al. , 2022, suggest that sharks are indeed foraging in the area. Other potential drivers that shape density at the aggregation site and deserve future consideration include intraspecific interactions (Schilds et al. 2019, Anderson et al. 2021a, such as competitive exclusion of smaller sharks from other areas used by larger sharks (Goldman & Anderson 1999, Martin et al. 2009), and as a refuge from predation (Pyle et al. 1999, Benson et al. 2018, Towner et al. 2022. Future research using UAVs could perform targeted behavioral observations, rather than density surveys as performed in this study, to better understand such drivers and the variable influence of these factors on different shark size classes. ...
Ontogenetic habitat shifts are a common feature of many marine species, including sharks, which face conservation threats when their distributions overlap with human resource extraction and habitat modification. White sharks Carcharodon carcharias , for example, exhibit a distinctly coastal phase as juveniles, with a limited distribution compared to the basin-scale range of adults. Using an unoccupied aerial vehicle (UAV), we studied a coastal aggregation site within a Southern California Bight nursery area to determine how fine-scale temporal and oceanographic factors affect white sharks at different developmental stages. White shark density, as measured via UAV, was highly variable across time of day and day of year, with modest variation across years. Typically, more sharks were observed in the late afternoon hours. Sharks, especially those <3 m total length, were observed more often during periods of colder seafloor temperatures, potentially reflecting avoidance of these colder, deeper waters by more cold-intolerant smaller white sharks. Alternate models incorporating sea surface temperature showed a very small but significant association between surface temperatures and <3 m total length white sharks for the months we surveyed, but no such association for larger sharks. There were no or only modest effects of visibility, swell height, chl a levels, sea state, and tidal height on UAV-observed shark density. Understanding how temporal patterns and oceanographic predictors of density change over time as well as how shark ontogeny interacts with these factors can help us to better understand how this species uses coastal habitats and predict when they may be more likely to share marine space with humans.
... throat, belly) are likely to have a greater success rate (Heithaus, 2001b;Melillo-Sweeting et al., 2014). Indeed, some shark species are known to attack by rushing vertically from depth to ambush prey (Martin et al., 2009;Martin & Hammerschlag, 2012). Similarly, no shark-inflicted scars were recorded on the head or jaws, which again would likely be fatal for the dolphin. ...
Understanding interactions within and between species is crucial to ecological research. However, for cetaceans such interactions can be difficult to observe in the field. Photographs offer an opportunity to study intra‐ and inter‐specific interactions, by capturing ‘snapshots’ of their occurrence over space and time. At‐surface and underwater photographs of bottlenose dolphins (Tursiops aduncus) inhabiting Ponta do Ouro Partial Marine Reserve (PPMR), Mozambique, were used to examine evidence of interactions with other dolphins, predators and ectoparasites. Intra‐specific scarring levels significantly differed by sex and age class, with males displaying more scarring than females. Similarly, adults had more scarring than juveniles or calves. Shark bites significantly differed in their distribution across dolphin body areas, with the dorsal side being more frequently wounded than the ventral side. The presence of barnacles was exclusive to fluke, dorsal and pectoral fins, and showed strong seasonal trends. Overall, this study demonstrates the value of photographs for examining marine ecological interactions. It provides the first insights regarding dolphin social behaviour, predation risk and health for this population. These in turn will support future research into the population dynamics and conservation of the PPMR dolphins, which is urgently required in the face of locally increasing anthropogenic pressures.
... Research across a wide range of species has shown that habitat use is in part influenced by the distribution of prey (e.g. Benoit-Bird et al., 2013;Heithaus et al., 2002;Jepsen et al., 2006;Martin et al., 2009;Papastamatiou et al., 2011;Zabel et al., 1995). Here, spatially resolved lemon shark foraging events occurred in areas of disproportionately higher Gerreidae abundance, their preferred prey . ...
Describing patterns in activity and behaviour of animals as they move through their environment helps to reveal fundamental aspects of their ecology and identify key habitat requirements. Nursery areas are used by many shark species and play an important role in maintaining the viability of populations. Although shark movements within nursery areas have been well studied, far less is known about how space use correlates with activity levels and specific behaviour. In the present study, we used combined accelerometer-acoustic transmitter tag packages to investigate fine-scale space use, activity and behavioural patterns of nursery-bound lemon sharks, Negaprion brevirostris. First, we constructed an ethogram to categorize specific behaviours from accelerometer data collected from seven sharks (97-122 cm total length) that were caught, tagged and observed in captivity for 3-6 days. Second, we conducted field trials with 19 sharks (78-169 cm total length), each tagged and actively tracked during 3-5 deployment days. We then used baited remote underwater video (BRUV) surveys to investigate potential overlap between shark foraging effort and prey distributions. Accelerometer and tracking data showed that the tidal phase significantly affected space use, activity and behaviour. Sharks used near- shore areas during the high tide periods where resting increased and activity levels were reduced. On falling tides, sharks moved farther from the shoreline and increased overall activity. Foraging effort peaked at low tide periods and foraging events overlapped with areas of disproportionately high preferred prey abundance. Ontogenetic patterns were also found in which larger sharks generally occupied larger home ranges, spent more time in areas farther offshore, rested less and foraged more than smaller individuals. These findings represent novel insights into nursery habitat use and behavioural trade-offs in lemon sharks and support more informed management for this threatened species.
... Studying environmental factors that can affect predator-prey interactions and predation frequencies is also important, considering the populations of many predators are declining globally [4]. Although several works describe the surface predatory behavior [5][6][7][8][9] and the causing the WSs to prefer the seal-shaped decoy instead of the tuna bait; and (iii) evaluate major environmental factors affecting predatory behavior. These aspects aim to confirm the influence of environmental factors on the feeding behavior of WSs. ...
The influence of environmental factors on prey discrimination of bait-attracted white sharks was studied over a six-year period (2008–2013) at Dyer Island Nature Reserve (Gansbaai, South Africa). Across 240 bait-attracted feeding events observed in this period, both immature and mature white sharks were attracted by the seal-shaped decoy rather than the tuna bait, except for the years 2008 and 2011. Tide ranges, underwater visibility, water temperature, and sea conditions were, in decreasing order, the factors which drove white sharks to select the seal-shaped decoy. High tide lowered the minimum depth from which sharks could approach seals close to the shore, while extended visibility helped the sharks in making predatory choices towards the more energy-rich prey source, the odorless seal-shaped decoy. On the contrary, warmer water is associated with an increase in phytoplankton that reduces underwater visibility and increases the diversity of teleosts including tuna—a known prey of white sharks—driving the sharks to favor the tuna bait. Overall, sea conditions were almost always slightly rough, ensuring a good average underwater visibility. Recommendations for future research work at this site are presented.
... Specifically, large females (>3.8 m TL) exhibited dominance over smaller individuals (from 3 to 3.8 m TL) while feeding from a whale carcass (Clua et al., 2013). Similar behaviour has been described in white sharks, Carcharodon carcharias, at both seal hunting sites (Martin et al., 2009) and whale carcasses (Dicken, 2008;Fallows et al., 2013). In the tourism provisioning context, size-dependent dominance has also been observed in female Caribbean reef sharks, Carcharhinus Although body size seems to play a role in observed patterns of space use, its overall importance remains unclear. ...
While a growing body of literature has shown that tourism provisioning can influence the behaviour of wildlife, how physiological state might be related to the nature and magnitude of these effects remains poorly understood. Physiological state, including reproductive and nutritional status, can have profound effects on an individual's behaviour and decision making. In the present study, we used multiple physiological markers related to reproductive (testosterone, 17β-oestradiol and progesterone), metabolic (corticosteroids) and nutritional ecology (stable isotopes and fatty acids), integrated with ultrasonography and passive acoustic telemetry to explore the possible relationship between physiological condition and space use of tiger sharks, Galeocerdo cuvier, exposed to dive tourism provisioning. Large, nongravid female tiger sharks, with higher plasma steroid levels (i.e. testosterone, 17β-oestradiol, relative corticosteroid), enriched δ¹⁵N and elevated nutritional status (in terms of fatty acids) spent proportionally more time at food provisioning sites compared to conspecifics. Testosterone levels also were positively correlated with the proportion of time spent at provisioning sites. Based on these results, we speculate that physiological condition plays a role in shaping the spatial behaviour of female tiger sharks within the context of food provisioning, whereby larger individuals, exhibiting higher testosterone levels and elevated nutritional status, show selective preferences for provisioning dive sites, where they outcompete conspecifics of relatively smaller size, lower testosterone levels and depressed nutritional state. While more studies are needed to explore whether sharks are making these decisions because of their physiological state or whether spending more time at provisioning sites results in altered physiological state, our findings highlight the importance of considering animal life stage, endocrine regulation, and nutritional condition when evaluating the biological impacts of provisioning tourism.
... For example, in 2007 GP was used to identify the anchor point of nesting bees (Raine et al, 2008). Other research has analysed the predatory patterns of great white sharks as they hunted cape fur seals (Martin et al, 2009) which also identified that the predator utilised a base or anchor point, similar to serial offenders (2009). ...
This study adds to the emerging literature in respect of foraging criminal offenders. Optimal forager theory is drawn from ecology where it is used to examine the movement of foraging animals. Over the past decade and a half this theory has crossed disciplines into the criminological sphere. Within the criminal context, it has been used successfully to support police crime prevention and reduction strategies, most notably within the area of domestic burglary. By identifying the presence of a foraging offender police analysts predict future areas they will target and use this information to direct police preventative patrols. Despite its widespread use within policing there is little research to support the existence of this subset of offender beyond examining their near repeat victim selection and crime scene behaviour. This study aims to build upon this previous research by using a case study approach to examine the geographical profiles, demographic and criminal conviction characteristics of police-identified foraging offenders. In doing so, it offers new insights and distinctions with existing burglary offender typologies that indicate that foragers may indeed be a legitimate typology of offender. The study also outlines its limitations and areas for future research that will enable this theory to be further explored.
... The geoprofile consists in an approximated localization of an area (often represented as a red area) containing the spreading centre, where the probability of finding it is higher than a given threshold (typically 95%). After its first use in criminology, GP was applied to biological problems such as the targeting of an infectious disease (Papini and Santosuosso 2016), the prediction of nest locations of bumble bees (Suzuki-Ohno et al. 2010), animal foraging (Le Comber et al. 2006;Raine et al. 2009) and shark hunting patterns (Martin et al. 2009). The obtained results can be compared to those of other analytical methods of mapping the higher or lower probability of crimes occurrence in a given area, as in Quick (2019). ...
Geographic Profiling (GP) attempts to reconstruct the spreading centre of a series of events due to the same cause. The result of the analysis provides an approximated localization of the spreading centre within an area (often represented as a red red), where the probability of finding it is higher than a given threshold (typically 95%). The analysis has as an assumption that the events will be likely to occur at very low probability around the spreading centre, in a ring-shaped zone called the buffer zone. Obvious examples are series of crimes perpetrated by an offender (unwilling to perpetrate offences close to home), or the localities of spread of an invasive species, where the buffer zone, if present, depends on the biological features of the species. Our first aim was to show how the addition of new events may change the preliminary approximate localization of the spreading centre. The analyses of the simulated data showed that if B , the parameter used to represent the radius of the buffer zone, varies within a range of 10% from the real value, after a low number of events (7–8), the method yields converging results in terms of distance between the barycentre of the red zone and the “real” user provided spreading centre of a simulated data set. The convergence occurs more slowly with the increase in inaccuracy of B . These results provide further validity to the method of the GP, showing that even an approximate choice of the B value can be sufficient for an accurate location of the spreading centre. The results allow also to quantify how many samples are needed in relation to the uncertainty of the chosen parameters, to obtain feasible results.
... [11][12][13]). More than two decades of monitoring shark-seal interactions at Seal Island in False Bay have revealed unusually clear-cut spatial and temporal variation in predation risk to seals from white sharks [14][15][16][17][18]. ...
Predators can impact prey via predation or risk effects, which can initiate trophic cascades. Given widespread population declines of apex predators, understanding and predicting the associated ecological consequences is a priority. When predation risk is relatively unpredictable or uncontrollable by prey, the loss of predators is hypothesized to release prey from stress; however, there are few tests of this hypothesis in the wild. A well-studied predator-prey system between white sharks (Carcharodon carcharias) and Cape fur seals (Arctocephalus pusillus pusillus) in False Bay, South Africa, has previously demonstrated elevated faecal glucocorticoid metabolite concentrations (fGCMs) in seals exposed to high levels of predation risk from white sharks. A recent decline and disappearance of white sharks from the system has coincided with a pronounced decrease in seal fGCM concentrations. Seals have concurrently been rafting further from shore and over deeper water, a behaviour that would have previously rendered them vulnerable to attack. These results show rapid physiological and behavioural responses by seals to release from predation stress. To our knowledge, this represents the first demonstration in the wild of physiological changes in prey from predator decline, and such responses are likely to increase given the scale and pace of apex predator declines globally.
... It could be argued that the reason for this is because of the theory of the buffer zone, a concept within geographical profiling that shows that an offender is unlikely to operate in the immediate vicinity of their home or base because it raises the perceived likelihood of apprehension (Rossmo, 2000). Other research has analysed the predatory patterns of white shark hunts as they engaged with cape fur seals (Rossmo and Hammerschlag;). Using geographical profiling techniques, it was identified that the predator utilised a base or anchor point, similar to serial offenders (2009; 115). The study also identified that the hunting area was not the area that offered the greatest access to prey, as one would expect but in fact seemed to show some cost benefit analysis by the sharks in identifying a zone which offered the highest balance of prey availability, capture rate and level of competition (2009; 116-7). ...
Drawn from ecology, the optimal forager predictive policing methodology has
been identified as the primary tasking tool used by police services to tackle
domestic burglary. Built upon established findings that the target selection
behaviour of foraging domestic burglary offenders can be predicted, this thesis
examines the physical offending and geographical characteristics of foraging
offenders in greater detail. This study evolves established research evidence by
drawing upon criminological methods that have potential to increase the
approaches effectiveness before testing their applicability in respect of foraging
criminals. Ecological research evidence relating to assumptions of foraging
behaviour are used to devise theoretical manifestations within criminal behaviour
which are subsequently tested for and used to build a theoretical model to
combat them.
The study achieves all of this through a number of key research chapters, these
include (1) identifying predictive thresholds for linking burglary offences
committed by foraging criminals (2) drawing on existing assumptions within
ecology the study then seeks to identify their presence within foraging criminals,
including the presence of significant crime displacement, and (3) geographical
profiling is identified and tested as a potential solution to combat the evasive
behaviour of foraging offenders as a response to the increased police presence
that the optimal forager model is designed to co-ordinate. Underpinning the study
throughout is an examination of the enablers and blockers present that impact
upon the effectiveness of such transitions of theory into practice. Overall, the
thesis provides new theoretical material by creating a framework of foraging
offender typologies. The key practical implications for policing include a model
for tackling the identified theoretical foraging typologies to increase the crime
prevention and reduction efforts in respect of domestic burglary.
... The most aggressive species toward humans worldwide are great white sharks (Carcharodon carcharias), tiger sharks (Galeocerdo cuvier), and bull sharks (Carcharhinus leucas), with several other species known to attack humans in more isolated occurrences (Bury et al. 2012;Byard et al. 2006;Clua and Séret 2010;Ihama et al. 2009;International Shark Attack File 2021;Martin et al. 2009;Nakaya 1993;Rathbun and Rathbun 1997;Ritter and Levine 2005;Rtshiladze et al. 2011;West 2011). Other, smaller species of shark are known at least to scavenge upon human remains, including the cookiecutter shark (Isistius brasiliensis) (Ellingham et al. 2017;Ribéreau-Gayon et al. 2018), and it is likely that other species may engage in this behavior, thus expanding the pool of possible taphonomic agents. ...
Marine environments and coastal areas are a frequent source of remains undergoing forensic investigation, given the frequency of remains introduced from homicide, suicide, and accidents, and the concentration of human activity along coastlines. This chapter examines the many types of taphonomic effects accrued in marine environments. These include (1) alterations by scavengers, including sharks and arthropods, (2) colonization/bioerosion by organisms, including algae/kelp, barnacles, mollusks, Osedax worms, coral, sponges, and bryozoans, (3) sediment abrasion, battering, rounding, windowing, and embedding and salt crystal formation, (4) marine bleaching and mineral staining, and (5) more general changes including fat leaching and overall bone preservation. The propensity for remains to be transported and the factors that increase this likelihood, including decompositional bloating, are also examined. In addition, this chapter presents methods of estimating the postmortem submergence interval (PMSI) in these environments, including degree of decomposition and the stage of marine abrasion and other accrued taphonomic effects on exposed bones.
... White sharks ambush seals off Seal Island, biting prey obliquely using their anterolateral teeth in a lateral snap 25 , and attack seals at the water surface using a steep vertical attack 26 . The bites on the humeri vary from superficial scrapes to deep bites penetrating the bone, suggesting that the shark and seal (carcass) were in motion. ...
A study of the Mio-Pliocene marine palaeoenvironment on South Africa’s west coast revealed aspects of the biology and behaviour of fossil marine mammals. Close examination showed that seals from Langebaanweg suffered from pathologies and bore marks of marine carnivore activity. This study adds to our knowledge of shark feeding behaviour in the geological past and is one of a few studies of sharks feeding on seals in the fossil record. Two incomplete seal humeri with shark tooth marks are the first documented evidence from South Africa’s Mio-Pliocene of such behaviour. These injuries show no healing, which suggests that the animals were most likely scavenged.
Significance:
• Fossil rich deposits at Langebaanweg contribute to the knowledge of South African Mio-Pliocene fossils by placing them in a global context.
• This study is one of five globally that have documented marine carnivores feeding on seals.
• This is the first description of white sharks feeding on seals from South Africa’s geological past.
• This study shows this behaviour was in place on South Africa’s coast as early as 5 million years ago.
• The injuries show no signs of healing, suggesting the most parsimonious explanation is that white sharks were scavenging seal carcasses.
... It is worth considering that the Bahamas is a hotspot for tiger sharks, especially the sampling site where females of mixed lifestages, including large pregnant individuals, aggregate (Sulikowski et al., 2016). Accordingly, it is plausible that smaller females have reduced foraging success due to increased competition from larger conspecifics given documented intra-specific competition found in other large sharks (e.g., Martin et al., 2009). Another possible explanation for the apparent lower nutritional food quality found in sharks sampled in the Bahamas could be related to provisioning dive tourism near the study site, where dive tourists attract and feed tiger sharks with fish carcasses. ...
How varying levels of human activity, such as proximity and size of the nearest market (i.e., market gravity), influence the nutritional ecology and physiological condition of highly migratory marine predators is poorly understood. In the present study, we used a non-lethal approach to compare the concentration of metabolic hormones (i.e. corticosteroids and thyroid hormones) and plasma fatty acids between juvenile female tiger sharks (Galeocerdo cuvier) sampled in two areas of the subtropical north Atlantic, which differed markedly in their levels of coastal urbanization, Florida and the Bahamas (high versus low, respectively). We hypothesized that juvenile female tiger sharks sampled in water surrounding high coastal urbanization (Florida), would exhibit evidence of lower prey quality and higher energetic demands as compared to individuals sampled in relatively less urbanized areas of Northern Bahamas. Results revealed that relative corticosteroid levels (a proxy for energy mobilization) were higher in juvenile female tiger sharks sampled in Florida; however, no differences were found in concentrations of thyroid hormones (proxies of energetic adjustments) between the two locations. We found higher percentages of omega-3 polyunsaturated fatty acids (indicative of high prey quality) in juvenile tiger sharks from Florida, whereas higher percentages of bacterial markers (often indicative of domestic sewage effluent) were detected in the individuals sampled in the Bahamas. Taken together, these findings do not suggest that the differences in nutritional quality and metabolic condition found between the two sampling locations can be fully attributed to foraging in areas exposed to differing levels of urbanization. We speculate that these patterns may be due to the highly migratory nature and generalist feeding strategy of this species, even at the juvenile life stage, as well as proximity of sampling locations from shore.
... Geographic profiling is widely used by law enforcement agencies around the world , but more recently has been applied to cases in ecology and epidemiology where spatial locations are associated with sightings of an invasive species or an instance of an infectious disease (Table 1). Geographic profiling boasts a variety of successful applications from invasion biology (Stevenson et al. 2012, Papini et al. 2013, Faulkner et al. 2016, Cerri et al. 2020, Heald et al. 2019 to animal behavior (Le Comber et al. 2006, Martin et al. 2009, Raine et al. 2009, Faulkner et al. 2015, human-wildlife conflict (Faulkner et al. 2018, Struebig et al. 2018, and epidemiology (Le Comber et al. 2011, Verity et al. 2014, Smith et al. 2015. ...
Geographic profiling, a mathematical model originally developed in criminology, is increasingly being used in ecology and epidemiology. Geographic profiling boasts a wide range of applications, such as finding source populations of invasive species or breeding sites of vectors of infectious disease. The model provides a cost‐effective approach for prioritizing search strategies for source locations and does so via simple data in the form of the positions of each observation, such as individual sightings of invasive species or cases of a disease. In doing so, however, classic geographic profiling approaches fail to make the distinction between those areas containing observed absences and those areas where no data were recorded. Absence data are generated via spatial sampling protocols but are often discarded during the inference process. Here we construct a geographic profiling model that resolves these issues by making inferences via count data, analyzing a set of discrete sentinel locations at which the number of encounters has been recorded. Crucially, in our model this number can be zero. We verify the ability of this new model to estimate source locations and other parameters of practical interest via a Bayesian power analysis. We also measure model performance via real‐world data in which the model infers breeding locations of mosquitoes in bromeliads in Miami‐Dade County, Florida, USA. In both cases, our novel model produces more efficient search strategies by shifting focus from those areas containing observed absences to those with no data, an improvement over existing models that treat these areas equally. Our model makes important improvements upon classic geographic profiling methods, which will significantly enhance real‐world efforts to develop conservation management plans and targeted interventions.
... Floating whale carcasses may also create opportunities for adult sharks to congregate before mating (Fallows et al. (2013). Martin et al. (2009) found that larger white sharks showed more focused and refined hunting strategies than smaller sharks suggesting that larger sharks may be more efficient at feeding on carcasses before they strand and thus reducing their interest in a carcass after stranding. This may bias our observations towards smaller sharks. ...
White sharks (Carcharodon carcharias) are attracted to and scavenge on floating whale carcasses. However, little is known about how stranded whale carcasses may affect their behaviour. With increasing whale populations and beach stranding events, sharks may be attracted to nearshore waters at carcass sites, increasing the potential conflict with human use. Here, we used aerial drones to assess whether white shark behaviour around stranded whale carcasses differs from their behaviour away from carcasses. We quantified white shark behaviour by measuring swim speed, net velocity, straightness and sinuosity of shark tracks, as well as the total length of each shark. White sharks in the vicinity of whale carcasses travelled at 0.46 m s⁻¹ (±0.06 SD) faster, were 0.26 m (±0.15 SD) longer, swam tracks that were 0.15 (±0.11 SD) lower on the straightness index, and showed more sinuous tracks by 0.07 (±0.02 SD), compared to sharks away from a carcass. The presence of a stranded whale carcass may, therefore, significantly altered the behaviour and size of white sharks close to shore. As white shark activity increases in a relatively small nearshore area, which was indicated by decreased straightness and increased sinuosity, there may be an elevated risk of shark interactions with water users in the vicinity of stranded whale carcasses.
... A positive relationship between these lipids has previously been reported in the serum and plasma of elas- The significantly higher variance in body condition, FFA and KB ratio present in immature G. cirratum may indicate that the energetic state of these sharks is more variable than that of mature individuals. It is likely that the foraging success of sharks increases with experience, size and age (e.g., Martin et al., 2009), therefore it is not surprising that immature G. cirratum would exhibit more variability in foraging success than mature sharks. Such variability could contribute to variability in energy reserves, manifesting as variation in body condition and KB ratio, as well as variability in plasma FFA values, which are known to fluctuate with recent feeding events (Wood et al., 2010). ...
Reported here are the relationships among morphological (i.e., body condition) and biochemical (i.e., plasma concentrations of triglycerides, cholesterol, free fatty acids, and ketone bodies and ketone body ratios) parameters related to energy storage and use, as well as the variation of such parameters, for 107 free‐ranging nurse sharks Ginglymostoma cirratum sampled off South Florida. Immature G. cirratum exhibited a higher variance in body condition, plasma free fatty acid concentrations and ketone body ratios compared to adults. Mature female G. cirratum had significantly higher body condition than mature males, driven by a seasonal increase in mature female body condition during the wet season. Mature male G. cirratum showed a decrease in the ketone body β‐hydroxybutyric acid during the dry season. Taken together, this study provides a baseline assessment of body condition and internal physiological state for a data‐poor marine species and demonstrates significant ontogenetic, sexual and seasonal variation in G. cirratum energetic state. As concluded by other studies of energy metabolism in free‐ranging sharks, this research highlights the importance of considering intraspecific patterns and sampling context for inferring the drivers of variation.
... Drones have also proven useful for behavioural observations and fine-scale tracking of various shark species [30,31,42,47]. Typically, obtaining data on shark movement and behaviour has largely been conducted using boat-based observations [33,48,49], underwater video [50], or more commonly, satellite and/or acoustic tracking methods [51,52]. However, in comparison to satellite tracking methods, drones provide highly detailed information at much finer scales. ...
The use of drones to study marine animals shows promise for the examination of numerous aspects of their ecology, behaviour, health and movement patterns. However, the responses of some marine phyla to the presence of drones varies broadly, as do the general operational protocols used to study them. Inconsistent methodological approaches could lead to difficulties comparing studies and can call into question the repeatability of research. This review draws on current literature and researchers with a wealth of practical experience to outline the idiosyncrasies of studying various marine taxa with drones. We also outline current best practice for drone operation in marine environments based on the literature and our practical experience in the field. The protocols outlined herein will be of use to researchers interested in incorporating drones as a tool into their research on marine animals and will help form consistent approaches for drone-based studies in the future.
... The finding that older individuals were less likely than young ones to attack the FM might reflect a difference in experience. It is known from several animal species that experience plays a major role in many contexts, such as hunting [36][37][38], foraging [39,40] or mating [41][42][43]. A considerable impact of age and/or experience on territory defence behaviour has already been shown in birds [44,45] and insects [46,47]. ...
The trade-off between speed and accuracy affects many behavioural processes like predator avoidance, foraging and nest-site selection, but little is known about this trade-off relative to territorial behaviour. Some poison frogs are highly territorial and fiercely repel calling male intruders. However, attacks need to be conducted cautiously, as they are energetically costly and bear the risk of own injury or accidentally targeting the wrong individual. In this study, we investigated the speed-accuracy trade-off in the context of male territoriality during the breeding season in the brilliant-thighed poison frog, Allobates femoralis. In our experiment, we presented the call of an invisible 'threatening' intruder together with a visible 'non-threatening' intruder, using acoustic playback and a frog model, respectively. Contrary to our prediction, neither reaction time nor approach speed of the tested frogs determined the likelihood of erroneous attacks. However, younger individuals were more likely to attack the non-threatening model than older ones, suggesting that experience plays an essential role in identifying and distinguishing rivalling individuals in a territorial context.
... Whilst the size classes of white sharks are larger around seal colonies, with an average of 3.6 m TL (Semmens et al., 2013;Watanabe et al., 2019) as opposed to 2.7 m (TL) in this study, the effect of shark size on swim speeds was relatively subtle. Track patterns and behavior were also different to those observed at seal colonies, suggesting that swim speed and associated behavior near the surf break to be characteristic of energy conservation and opportunistic foraging, rather than actively patrolling for prey (Martin et al., 2009;Semmens et al., 2013). However, as this was an observational study limited to relatively short tracking durations and by the numbers of white sharks, it is also plausible that the observed behavior would change with provisional prey items such as seals or whale carcasses. ...
Many large coastal sharks are vulnerable to population declines, however, conflict with human activities often results in unselective culls. Successfully and non-destructively, addressing human-wildlife conflicts requires understanding of animal behavior. However, knowledge about white shark (Carcharodon carcharias) behavior near surf zones, where shark bites usually occur, is still limited. We used drones to obtain high-resolution tracks of 108 white sharks directly off coastal beaches on the east coast of Australia. White sharks ranged from 1.9 to 4.0 m (total length) and typically swam parallel to the beach line at an average speed of 0.82 m s −1 (∼3.0 km h −1), with behavior being characteristic of energy conserving motion and foraging. Notably the presence of schools of fish increased mean swim speeds of sharks by 0.33 m s −1 and caused tracks to be more convoluted. White sharks were also observed to swim straighter and faster with time either side of midday, increasing predicted mean swim speeds by 0.11 m s −1 , and net travel velocities by 0.25 m s −1. White sharks also displayed inquisitive behavior toward various potential food and non-food items. We demonstrate that white sharks display largely predictable track trajectories and slow movement speeds along coastal beaches, which has utility in further developing non-destructive shark mitigation strategies. Whilst some of the behavior observed might support the exploratory bite hypothesis, there is likely an increased risk of a shark bite to bathers during situations where there are large shark-attracting food sources present.
... The geoprofiles does not provide exactly the center of origin of the event, but rather provide areas at different priority on the map with a variable probability density [31,32]. After its first use in criminoloy, PGP was applied to biological problems such as the targeting of an infectious disease [27], the prediction of nest locations of bumble bees [39], animal foraging [21,30], sharks hunting patterns [24] and even the distribution pattern of V2 bombing [3]. More recently, PGP was used to guess the source of an invasion by alien organisms using the positions of their current populations [8,28,38]. ...
Abstract The analysis of big data is a fundamental challenge for the current and future stream of data coming from many different sources. Geospatial data is one of the sources currently less investigated. A typical example of always increasing data set is that produced by the distribution data of invasive species on the concerned territories. The dataset of Drosophila suzuki invasion sites in Europe up to 2011 was used to test a possible method to pinpoint its outliers (anomalies). Our aim was to find a method of analysis that would be able to treat large amount of data in order to produce easily readable outputs to summarize and predict the status and, possibly, the future development of a biological invasion. To do that, we aimed to identify the so called anomalies of the dataset, identified with a Python script based on the machine learning algorithm “Isolation Forest”. We used also the K-Means clustering method to partition the dataset. In our test, based on a real dataset, the Silhouette method yielded a number of clusters of 10 as the best result. The clusters were drawn on the map with a Voronoi tessellation, showing that 8 clusters were centered on industrial harbours, while the last two were in the hinterland. This fact led us to guess that: (1) the main entrance mechanisms in Europe may be the wares import fluxes through ports, occurring apparently several times; (2) the spreading into the inland may be due to road transportation of wares; (3) the outliers (anomalies) found with the isolation forest method would identify individuals or populations that tend to detach from their original cluster and hence represent indications about the lines of further spreading of the invasion. This type of analysis aims hence to identify the future direction of an invasion, rather than the center of origin as in the case of geographic profiling. Isolation Forest provides therefore complimentary results with respect to PGP. The recent records of the invasive species, mainly localized close to the outliers position, are an indication that the isolation forest method can be considered predictive and proved to be a useful method to treat large datasets of geospatial data.
... Other than that, the decreasing number of white shark problem has motivated us to choose this dataset [18]. The negative image of the white shark and the fear it projected on humans often resulted in unwarranted killing of the species [19]. These actions are made worse by the proximity of white shark feeding and breeding areas to coastal human populations of the world's sharks and rays [20]. ...
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
... GP is common in criminology, where the spatial locations of crimes are used to calculate the probability of occurrence of the offender's residence for each point over a certain geographical area. GP outperforms classical measures of spatial tendency, and many ecologists found it good for tracing back the origin of individuals that could move across space (Raine et al. 2008;Martin et al. 2009;Faulkner et al. 2015Faulkner et al. , 2017. We adopted a Bayesian GP algorithm (Verity et al. 2014), requiring only the specification of a distribution parameter, indicating a plausible maximum extent to which individuals could move. ...
Eradication of invasive alien species is a form of pest control linked to biodiversity conservation , which usually involves animal killing. Squirrels are prominent among invasive alien species in Italy, with four species introduced. Three of them are included within the list of alien species of European concern, and their eradication and control is recommended. However, their local control is not an easy task, being often hindered by the general public. We propose a socio-ecological approach to evaluate the feasibility of eradicating Siberian chipmunks Eu-tamias sibiricus populations in Italy. We performed a structured questionnaire to assess the social perception of invasive Siberian chipmunks in urban parks, and to identify groups of visitors who might oppose eradication. We also carried out geographic profiling to test for the spatial expansion of chipmunk populations. Overall, park visitors regarded chipmunks positively and appreciated to see them, but human-chipmunk interactions were still rare. We did not identify any group of visitors with a strong attachment to chipmunks, who might oppose future control programs. Geographic profiling showed that chipmunks in Valeggio sul Mincio are starting to expand().,-volV) (01234567 89().,-volV) outside of their introduction site. Data from questionnaires show that chipmunks eradication, coupled with adequate communication initiatives, might be feasible. Moreover, geographic profiling indicates that time for a rapid removal is running out. Socio-ecological approaches, combining the analysis of structured questionnaires administered to stakeholders and statistical modeling of pest observations, could be a valuable tool to decide the feasibility and the urgency of invasive alien species control.
... White sharks are present and highly active in preying upon Cape fur seals in both Mossel Bay (Johnson et al. 2009a) and False Bay (Martin et al. 2005, Laroche et al. 2008, Martin et al. 2009). Based both on their ambush hunting behaviour (Martin et al. 2005, Martin & Hammerschlag 2012) and retinal morphology (Gruber 1975), white sharks most likely require at least some light to hunt. ...
White sharks (Carcharodon carcharias) are highly visual predators, leading to the hypothesis that the predation risk for foraging Cape fur seals (Arctocephalus pusillus pusillus) might differ with ambient light conditions. This study investigated the relationship between environmental fluctuations of ambient light and the traversing behaviour of Cape fur seals in and out of their colony at Mossel Bay, South Africa to better describe potential predator avoidance strategies. A total of 12,144 traversing events were observed over a four-year period and there was an overall trend for Cape fur seals to traverse less often but in relatively larger group sizes during periods when white sharks are suggested to be more active. Specifically, Cape fur seal activity was reduced during winter when white sharks are most actively hunting, and most traversing behaviour occurred at night when Cape fur seals were less likely to be detected by white sharks. However, among nocturnal observations Cape fur seal group sizes increased significantly with moonlight. Although nocturnal predations of Cape fur seals by white sharks have been observed before in Mossel Bay, this is the first study to indicate Cape fur seals might respond to the increased risk of improved white shark visual acuity during moonlit nights by seeking safety in numbers while foraging. Further investigations are needed to assess the effect of the lunar cycle on white shark nocturnal hunting behaviour, but observations presented here suggest that white sharks may pose a bigger threat to Cape fur seals under the light of a full moon.
... Vision is the primary sense white sharks use when stalking seals from below (Strong Jr 1996). The vertical visibility at Seal Island is relatively low (~ 7 to 15 m) due to the continual release of seal waste from the island (Martin et al. 2009). Given that all three breach approaches commenced at depths within or near the bounds of this visibility estimate (see Table 1), we assume that the beginning of the breach approach marks the moment when the shark visually locates the seal on the surface. ...
In comparison to other behaviours, large predators expend relatively large amounts of energy foraging for prey, based on expected high return. Documenting how they manage costs and benefits of feeding is difficult, particularly for marine predators. In July and August of 2004 and 2005, we combined animal-borne video, accelerometry and depth sensors to examine the underwater behaviour during white shark (Carcharodon carcharias) breaching at Seal Island, South Africa (34.1373°S, 18.5825°E)—where sharks launch from the water while attacking Cape fur seals (Arctocephalus pusillus pusillus). We show that breaching begins at depths up to 20 m, is characterised by a brief (~ 7 to 16 s) ascent to the surface during which pitch angle increases by ~ 30° and both tail-beat frequency and swim speed (determined using biomechanical principles) increase by a maximum of 6.5-fold (0.39–2.50 Hz and 1.0–6.5 m s⁻¹, respectively). Sharks also demonstrated the ability to rapidly adjust their approach to the seal during ascent. Dominant tail-beat frequency during breaching was 2.1–4.2 times higher (0.83–1.67 Hz) than during non-predatory ascents (0.4 Hz), suggestive of the large increase in power required to breach. Examination of foraging behaviour through biologger deployments may play an increasingly important role in predicting the resource requirements of large predators and developing appropriate conservation measures, as their populations are generally under threat world-wide.
... To maximize net energy gains, white sharks are expected to employ behavioural strategies that increase prey encounter rates while reducing the energetic cost of swimming. Despite previous studies on the movement patterns of white sharks near seal colonies (recorded by acoustic telemetry) (Goldman and Anderson, 1999;Huveneers et al., 2013;Jewell et al., 2014;Klimley et al., 2001;Towner et al., 2016), spatiotemporal distributions of seal-predation attempts (directly observed from a boat) (Martin et al., 2005(Martin et al., , 2009 and the estimates of daily energy expenditure (Carey et al., 1982;Semmens et al., 2013), the potential behavioural strategies and their consequence on energetics in white sharks have not been sufficiently addressed. ...
Some fishes and sea turtles are distinct from ectotherms by having elevated core body temperatures and metabolic rates. Quantifying the energetics and activity of the regionally endothermic species will help us understand how a fundamental biophysical process (i.e. temperature-dependent metabolism) shapes animal ecology; however, such information is limited owing to difficulties in studying these large, highly active animals. White sharks, Carcharodon carcharias, are the largest fish with regional endothermy, and potentially among the most energy-demanding fishes. Here, we deployed multi-sensor loggers on eight white sharks aggregating near colonies of long-nosed fur seals, Arctocephalus forsteri, off the Neptune Islands, Australia. Simultaneous measurements of depth, swim speed (a proxy for swimming metabolic rate) and body acceleration (indicating when sharks exhibited energy-efficient gliding behaviour) revealed their fine-scale swimming behaviour and allowed us to estimate their energy expenditure. Sharks repeatedly dived (mean swimming depth, 29 m) and swam at the surface between deep dives (maximum depth, 108 m). Modal swim speeds (0.80-1.35 m s-1) were slower than the estimated speeds that minimize cost of transport (1.3-1.9 m s-1), a pattern analogous to a 'sit-and-wait' strategy for a perpetually swimming species. All but one shark employed unpowered gliding during descents, rendering deep (>50 m) dives 29% less costly than surface swimming, which may incur additional wave drag. We suggest that these behavioural strategies may help sharks to maximize net energy gains by reducing swimming cost while increasing encounter rates with fast-swimming seals.
... GP outperforms classical measures of spatial tendency, and many ecologists found it good for tracing back the origin of individuals that could move across space. [32][33][34][35] We adopted a Bayesian GP algorithm, 36 requiring only the specification of a distribution parameter, indicating a plausible maximum extent to which individuals could move. Based on available evidence indicating that chipmunks usually disperse within a few hundred meters from their birthplace, 37-38 we opted for a dispersal parameter of 1 km. ...
BACKGROUND: Eradication of invasive alien species is a form of pest control linked to biodiversity conservation that usually involves killing animals. Squirrels are prominent among invasive alien species in Italy with four species introduced. Three of them are included within the list of alien species of European concern and their eradication and control is recommended. However, their local control is not an easy task, being highly appreciated by the general public. We propose a socio-ecological approach to evaluate the feasibility of eradicating Siberian chipmunks (Eutamias sibiricus) populations. We performed a structured questionnaire to assess the social perception of invasive Siberian chipmunks in urban parks where they occur and to identify groups of visitors who might oppose eradication. We also carried out geographic profiling to test for the spatial expansion of chipmunk populations.
RESULTS: Overall, park visitors regarded chipmunks positively and appreciated to see them, but human-chipmunk interactions were still rare. We did not identify any group of visitors with a strong attachment to chipmunks, who might oppose future control programs. Geographic profiling showed that chipmunks in Valeggio sul Mincio are starting to expand outside of their introduction site.
CONCLUSIONS: Data from questionnaires show that chipmunks eradication, coupled with adequate communication initiatives, might be feasible. Moreover, geographic profiling indicates that time for a rapid removal is running out. Socio-ecological approaches, combining the analysis of structured questionnaires administered to stakeholders and statistical modeling of pest observations, could be a valuable tool to decide the feasibility and the urgency of invasive pest control.
... Furthermore, geographic profiling, the statistical technique originally developed in criminology has recently been applied to biological data such as the investigation of the point of origin of a biological invasion (Santosuosso and Papini, 2016), to predict multiple nest locations of bumble bees (Suzuki-Ohno et al., 2010) and hunting patterns of white shark (Martin et al., 2009). ...
... Despite all these limits, the GP formula works well also in cases where it has not to do with criminal events but rather of purely biological nature. For example GP can be used for the identification of hunting trails of white sharks [21] or to identify the place of origin of invasive species [2,3,8]. SOME SOLUTIONS A method to solve at least one of the points of the list above may be to automatically partition the data by some clustering algorithm in order to highlight any groups generated by more than a single agent, so as to separate events on the basis of different origins. ...
The Geographic Profiling (GP) is a data analysis tool that has great potential. Presently, it is used only minimally, and is almost always used “as it is”, independently on other analysis or data processing methods. GP was initially created as a forensic tool, to find the origin of a series of events (crimes) done by a single actor. However, using this method in integration with others, it is possible to enlarge the opportunities of geographical data analysis.
The promising results of this method in integration with others, even if some of them are quite well known methods since many years – and thus well tested – show a number of further possible applications. Here we treat data clustering and partitioning with Kmeans and Dbscan methods; space partitioning (Voronoi tessellation) and a method to assign weights to the events constituting the data set. The software used in this review was written in Python, was released under GPL license and is available on Bitbucket (https://bitbucket.org/ugosnt/al_and_ugo/).
... Attacks are concentrated on the southern side of the Island, close to shore (within 2 km). By positioning at the south end of Seal Island where the majority of predatory activity occurs, we were able to survey the waters surrounding the island for predations up to a distance of at least 3 km, although the majority of predations occur within 400 m of southwest end of the island (Martin et al. 2009). ...
Predators can impact ecosystems through consumptive or risk effects on prey. Physiologically, risk effects can be mediated by energetic mechanisms or stress responses. The predation-stress hypothesis predicts that risk induces stress in prey, which can affect survival and reproduction. However, empirical support for this hypothesis is both mixed and limited, and the conditions that cause predation risk to induce stress responses in some cases, but not others, remain unclear. Unusually clear-cut variation in exposure of Cape fur seals (Arctocephalus pusillus pusillus) to predation risk from white sharks (Carcharodon carcharias) in the waters of Southwestern Africa provides an opportunity to test the predation-stress hypothesis in the wild. Here, we measured fecal glucocorticoid concentrations (fGCM) from Cape fur seals at six discrete islands colonies exposed to spatiotemporal variation in predation risk from white sharks over a period of three years. We found highly elevated fGCM concentrations in seals at colonies exposed to high levels of unpredictable and relatively uncontrollable risk of shark attack, but not at colonies where seals were either not exposed to shark predation or could proactively mitigate their risk through antipredatory behavior. Differences in measured fGCM levels were consistent with patterns of risk at the site and seasonal level, for both seal adults and juveniles. Seal fGCM levels were not correlated with colony population size, density, and geographic location. Investigation at a high risk site (False Bay) also revealed strong correlations between fGCM levels and temporal variation in shark attack rates, but not with shark relative abundance. Our results suggest that predation risk will induce a stress response when risk cannot be predicted and/or proactively mitigated by behavioral responses.
... Geoprofiling is a method originally developed for the statistical evaluation in criminology, where it has been successfully utilised for identification of the most likely home addresses of crime offenders based on serial delinquencies (Stevenson et al., 2012). Recently, the method has also been applied to tasks disparate from its original purpose, such as in field of species modelling (Martin et al., 2009;Raine et al., 2009) or spatial epidemiology (Buscema et al., 2009;Le Comber et al., 2011), where single or multiple sources (nests, feeding places, outbreaks, etc.) may be identified. The technique uncovers common hidden geographical patterns of events and/or similar behaviour. ...
Inspired by local outbreaks of campylobacteriosis in the Czech Republic in 2010 linked to the debate about alleged health risks of the raw milk consumption, a detailed study was carried out. Firstly, scanning was utilised to identify spatio-temporal clusters of the disease from 2008 to 2012. Then a spatial method (geographical profiling originally developed for criminology) served as assessment in selecting fresh-milk vending machines that could have contributed to some of the local campylobacteriosis outbreaks. Even though an area of increased relative risk of the disease was identified in the affected city of České Budějovice during January and February 2010, geoprofiling did not identify any vending machines in the area as the potential source. However, possible sources in some nearby cities were suggested. Overall, 14 high-rate clusters including the localisation of 9% of the vending machines installed in the Czech Republic were found in the period 2008-2012. Although the vending machines are subject to strict hygiene standards and regular testing, a potential link between a small number of them and the spatial distribution of campylobacteriosis has been detected in the Czech Republic. This should be taken into account in public health research of the disease.
... Geographic profiling is a statistical technique that was original developed in criminology to prioritise large lists of suspects in cases of serial crime such as murder, rape and arson (Rossmo 2000). More recently, the model has been successfully applied to epidemiological and biological data sets such as locating animal roost and nest sites using as input their foraging locations (Le Comber et al. 2006;Buscema et al. 2009;Martin et al. 2009;Raine et al. 2009;Le Comber et al. 2011;Le Comber & Stevenson et al. 2012;Verity et al. 2014;Faulkner et al. 2015Faulkner et al. , 2016. In criminology, the model uses the locations of linked crimes to calculate the probability of offender residence for each point within the study area. ...
Poaching can have devastating impacts on animal and plant numbers, and in many countries has reached crisis levels, with illegal hunters employing increasingly sophisticated techniques. Here, we show how geographic profiling – a mathematical technique originally developed in criminology and recently applied to animal foraging and epidemiology – can be adapted for use in investigations of wildlife crime, using data from an eight-year study in Savé Valley Conservancy, Zimbabwe that in total includes more than 10,000 incidents of illegal hunting and the deaths of 6,454 wild animals. Using a subset of these data for which the illegal hunters’ identities are known, we show that the model can successfully identify the illegal hunters’ home villages using the spatial locations of hunting incidences (for example, snares) as input, and show how this can be improved by manipulating the probability surface inside the Conservancy to reflect the fact that – although the illegal hunters mostly live outside the Conservancy, the majority of hunting occurs inside (in criminology, ‘commuter crime’). The results of this analysis – combined with rigorous simulations – show for the first time how geographic profiling can be combined with GIS data and applied to situations with more complex spatial patterns – for example, where landscape heterogeneity means that some parts of the study area are unsuitable (e.g. aquatic areas for terrestrial animals, or vice versa), or where landscape permeability differs (for example, forest bats tending not to fly over open areas). More broadly, these results show how geographic profiling can be used to target anti-poaching interventions more effectively and more efficiently, with important implications for the development of management strategies and conservation plans in a range of conservation scenarios.
... Juvenile tiger sharks might use Cerro-Ballena as a daytime refuge from which to conduct foraging excursions at nearby nocturnal feeding grounds (e.g., Cuatro Hermanos islets or the various adjacent seamounts). Patterns of spatial segregation of size classes have been reported in other large sharks in feeding areas elsewhere, such as white sharks at seal-colony hunting grounds [65,66]. Juveniles possibly remain resident in the GMR year-round, as limitations on broader movements for juvenile tiger sharks have been previously documented elsewhere [25,47]. ...
The potential effectiveness of marine protected areas (MPAs) as a conservation tool for large sharks has been questioned due to the limited spatial extent of most MPAs in contrast to the complex life history and high mobility of many sharks. Here we evaluated the movement dynamics of a highly migratory apex predatory shark (tiger shark Galeocerdo cuvier) at the Galapagos Marine Reserve (GMR). Using data from satellite tracking passive acoustic telemetry, and stereo baited remote underwater video, we estimated residency, activity spaces, site fidelity, distributional abundances and migration patterns from the GMR and in relation to nesting beaches of green sea turtles (Chelonia mydas), a seasonally abundant and predictable prey source for large tiger sharks. Tiger sharks exhibited a high degree of philopatry, with 93% of the total satellite-tracked time across all individuals occurring within the GMR. Large sharks (> 200 cm TL) concentrated their movements in front of the two most important green sea turtle-nesting beaches in the GMR, visiting them on a daily basis during nocturnal hours. In contrast, small sharks (< 200 cm TL) rarely visited turtle-nesting areas and displayed diurnal presence at a third location where only immature sharks were found. Small and some large individuals remained in the three study areas even outside of the turtle-nesting season. Only two sharks were satellite-tracked outside of the GMR, and following long-distance migrations, both individuals returned to turtle-nesting beaches at the subsequent turtle-nesting season. The spatial patterns of residency and site fidelity of tiger sharks suggest that the presence of a predictable source of prey and suitable habitats might reduce the spatial extent of this large shark that is highly migratory in other parts of its range. This highly philopatric behaviour enhances the potential effectiveness of the GMR for their protection.
... However, its distribution appears to be discontinuous and major aggregations tend to occur in the vicinity of highly productive habitats with high marine mammal abundance (particularly pinnipeds) (Compagno 1984). Major white shark aggregations have been documented in central California (Ainley et al. 1985;Klimley 1985;Klimley et al. 1992;Long 1994), the shelf waters of the mid-Atlantic bight (Casey and Pratt 1985), the south and west coast of Australia (McCosker 1987;Bruce 1992;Strong et al. 1992), in New Zealand (Duffy et al. 2012;Francis et al. 2015) and South Africa (Cliff et al. 1989;Ferreira and Ferreira 1996), especially in the Western Cape province (Martin et al. 2005(Martin et al. , 2009Kock et al. 2013). White sharks have only been studied in regions of highest abundance resulting in limited knowledge of their movements, ecology and biology in areas with lower densities (Fergusson 1996). ...
The occurrence of the white shark, Carcharodon carcharias, in the Mediterranean Sea has been reported since the Middle Ages (476–1453). Several studies have documented its presence in various areas of the basin, but no comprehensive review of the distribution and status of this species is available for the area. We compiled a total of 628 white shark records from 476 to 2015. Data suggests that the white shark is more common in the western Mediterranean Sea, especially in the Adriatic Sea and in the Sicilian Channel and is more frequently observed during summer months. However, analysis using night-time satellite imagery showed the existence of an anthropogenic bias in the distribution of white sharks. All size classes have been recorded in the region. However, the highest occurrence of young of the year has been recorded in the Sicilian Channel, in the Adriatic Sea and in the Aegean Sea, in summer, suggesting these areas might serve as nursery grounds. In the Mediterranean Sea, the white shark exhibits a broad diet. The most common prey found include small cetaceans (Tursiops truncatus, Stenella coeruleoalba), tuna (Thunnus spp.), swordfish (Xiphias gladius) and loggerhead sea turtle (Caretta caretta). A total of 53 white shark records refer to interactions between sharks and humans that resulted in a detrimental impact on humans, which include 42 bites and 11 reports of the presence of human remains in the stomach of captured animals. Analysis of the temporal variation in mean total lengths of white sharks found a decreasing trend from 1913 to 2012. The decreasing length of white sharks suggests this species might be declining in the Mediterranean Sea.
... GP has been used in biology to analyze the origins of infectious diseases (Le Comber et al., 2011;Verity et al., 2014), to predict the locations of multiple nest locations of bumble bees (Suzuki-Ohno et al., 2010), and to study the patterns of animal foraging (Le Comber et al., 2006;Raine et al., 2009) and great white sharks predating on seals (Martin et al., 2009). Stevenson et al. (2012) used GP to identify the origin of the invasion of a species, starting from the current known locations of their populations. ...
The use of geographic profiling (GP), based on “Rossmo’s formula”, a technique derived from criminology, has been previously proven to be effective in assessing the origin of invading species. The application on Caulerpa taxifolia showed the most probable center of spread of the invasion. This article discusses a method of assessing the degree of robustness of the results obtained with Rossmo’s method. To provide an evaluation of the reliability of geographic profiling results we used the jackknife technique, randomly eliminating part of the data set for a given number of replicates (500) in order to analyze the obtained result for each replicate. In GP the results are a series of images with geoprofiling prioritization, each produced with one of the replicates. These images can be summarized in three different ways: (1) OR, depicting all the high probability pixels from the series of replicates; (2) AND, depicting only those high probability pixels present in every replicate; and (3) MEAN, depicting the mean color value for each pixel calculated from all the replicates. We show that jackknifing can be a useful method to increase robustness of GP analysis, both in criminology, epidemiology and biological invasions. Summarizing jackknifing results with the OR logical operator yields highest sensitivity and worst specificity, while the use of the AND operator increases specificity but reduces sensitivity. Using the mean of the pixel values maintains the visualization of the areas of highest priority (specificity), while also showing the surrounding area with varying colors, with a meaning analogous to confidence limits.
Dada a elevada diversidade nas estratégias de história de vida, os elasmobrânquios (tubarões e raias) tornam-se interessantes modelos para o estudo de relações entre a fisiologia e interações ecológicas no ambiente marinho. Embora os esforços para a conservação dos elasmobrânquios, que é atualmente o segundo grupo de vertebrados mais ameaçado do planeta, tenha estimulado um aumento no número de estudos sobre os padrões ecológicos e impactos antrópicos, pouco ainda se sabe sobre sua fisiologia. Assim, nesta tese de doutorado foram investigadas as variações fisiológicas sazonais e espaciais associadas ao estágio de vida e comportamento de tubarões de diferentes histórias de vida, utilizando múltiplas ferramentas não-letais para fornecer uma melhor compreensão dos padrões energéticos e reprodutivos, além de uma base fisiológica que ajude a prever os efeitos de distúrbios ambientais nos tubarões. O capítulo 1 aborda as variações inter- e intraespecíficas na ecologia nutricional de tubarões de diferentes estratégias de história de vida em um sistema insular oceânico protegido, o Arquipélago de Fernando de Noronha. Foram abordados também as variações nos padrões de dieta e condição nutricional e metabólica relacionados à reprodução de fêmeas de tubarões-tigre Galeocerdo cuvier (capítulo 2) e machos de tubarões-lixa Ginglymostoma cirratum e tubarões-galha-preta Carcharhinus limbatus (capítulo 3). Os capítulos 4, 5 e 6 abordam os efeitos da vida urbana na condição nutricional e padrões alimentares de tubarões com diferentes estilos de vida, o tubarão-lixa, o tubarão-galha-preta e o tubarão-tigre, respectivamente. Os resultados mostraram que a influência da urbanização na qualidade da dieta dos tubarões parece ser mais pronunciada em espécies sedentárias, como o tubarão-lixa, quando comparado com espécies mais ativas. Por fim, o capítulo 7 trouxe uma abordagem inédita na pesquisa de tubarões, combinando múltiplos marcadores fisiológicos com informações obtidas através de ultrassonografia e da telemetria acústica passiva para entender relações entre os aspectos fisiológicos e comportamentais de tubarões-tigre expostos ao turismo de alimentação. Os resultados demonstraram que o estágio de vida, a regulação endócrina e a condição nutricional influenciam e/ou são influenciadas pelo tempo que os tubarões passam interagindo com o turismo de alimentação. Em conjunto, os resultados mostraram que os biomarcadores nutricionais, reprodutivos e metabólicos utilizados nesta tese fornecem uma poderosa ferramenta para descrever padrões ecológicos complexos dos tubarões, especialmente quando combinados com outras tecnologias para rastreamento da movimentação e identificação do estágio reprodutivo dos tubarões.
Modern crime analysts have multiple tools at their disposal, including geographic profiling software and crime prediction software. This study uses said software to analyze data from descriptions of pirate attacks in the seventeenth and eighteenth centuries in the Caribbean. The results show significant similarities between historical pirates and modern criminals, but also point to important differences. Although both crime prediction and geographic profiling algorithms show a degree of accuracy, many pirates often changed their anchor point, making it difficult to find appropriate crime series. When searching for artifacts related to pirate activity, criminological tools might be helpful, but only if used carefully.
Sharks are among the most endangered nonhuman animals on the planet because of industrial fishing, the shark meat and fin trade, expanding recreational fishing, and other anthropogenic causes. White sharks (Carcharodon carcharias), the most visible in popular culture, remain vulnerable (VU, IUCN Red List) and understudied, although population recovery is having a measure of success in regions like the Eastern Pacific and the Northern Atlantic of the United States. As numbers rise, Jaws associations also remain in vogue in programming that emphasizes human–wildlife** conflict such as Shark Week’s Great White Serial Killer Lives. Network marketing typically promotes this content by hyping shark science. Textual analysis, however, suggests that exposure to pseudoscientific narratives and unethical fear-inducing images is counterproductive to wider support for conservation programs and public recognition for sharks’ rights to their habitats.
Title: Toscana virus meningitis and meningo-encephalitis: an analysis on clinical, laboratory and epidemiological charactersistics, with Geoprofiling methods, of the observed cases between 2008 and 2018 at Azienda Ospedaliero-Universitaria di Careggi, Florence
Introduction: The Differential diagnosis between various etiologies of patients with aseptic meningitis often represents a challenge for the physician, associated with the necessity of an over-expense of resources for diagnostic tools, not always with diriment results. Moreover the presence of a limited casistic of Toscana virus aseptic meningitis in scientific literature limits a precise definition of typical clinical and laboratory characteristics of these forms.
Objectives:
-To evaluate peculiar clinical and laboratory characteristics of Toscana virus meningitis (TOSV) useful to differentiate from other causes of aseptic meningitis (herpesviruses and enteroviruses).
-To analyze the case distribution of patients from the Azienda Ospedaliera Universitaria Careggi (AOUC) to find any infection focuses in the Florentine's area.
Materials and methods: We analyzed the data found in hospital registers of patients hospitalized in the Infectious and Tropical Diseases sector of the AOUC from 2008 to 2018. In addiction to this study we incorporated an epidemiological analysis restricted to the up-mentioned patients with the goal of finding any diffusion areas. The multivariate analysis was conducted with a discriminatory analysis and a logistic regression, developed after the ROC analysis of the variable with proven significance at the univariate analysis. The epidemiological study was conducted with Geoprofiling methods.
Results: We found significant differences between the various forms in our casistic. The main differences between TOSV and Herpes forms resulted in the clinical presentation, with a relative homogeneity between the laboratory variables, while the comparison between TOSV and enterovirus revealed significant differences in laboratory variables, especially for liquor parameters. The epidemiological analysis gave us interesting information about the vector distribution, thou the value of this information should be validated with field research.
Conclusions: Our study, by using the biggest casistic of TOSV aseptic meningitis existing in scientific literature, evidenced interesting peculiarity of these forms that could be used for a better identification of different etiologies of aseptic meningitis during everyday practice and could be used in the future to build algorithms or scores for this pathological entity. The results of the Geoprofiling analysis should be evaluated with field research.
RESUMEN No tenemos constancia de la existencia en este país de estudios sobre perfil geográfico de sujetos con un comportamiento incendiario en la vía pública, ni tampoco sobre investigaciones que hayan comprobado la eficacia de las estrategias del geoperfil para identificar, con cierta precisión, el área donde es más probable que resida el responsable de los incendios urbanos. En este estudio se propone, formula y comprueba una calibración en el parámetro B (zona de seguridad) de la ecuación CGT propuesta por Rossmo (1995) para identificar el domicilio del incendiario, según sea éste de tipo serial, en masa o espontáneo. Para ello se analizan tres casos de incendiarios: en Santander en 2011, en Palma de Mallorca en 2016 y en Elche en 2017. El ajuste que se propone para el parámetro B reduce tanto la distancia de error como los costes de búsqueda en los tres casos estudiados. Palabras clave: perfil geográfico, incendiarios urbanos, zona de seguridad, punto de anclaje.
ABSTRACT Studies on the geographical profile of subjects with incendiary behavior on public roads have not been developed in our country, nor has the effectiveness of geoprofile strategies been proven to identify, with a certain precision, the area where it is most likely to reside the responsible for urban fires. In this study, a calibration is proposed, formulated and checked in the B value (buffer zone) of the CGT equation proposed by Rossmo (1995) to identify the residence of the arsonist, depending on whether they are serial, mass or spree. For this, three cases of arsonists are analyzed: one in Santander in 2011, another in Palma de Mallorca.
La correspondencia debe dirigirse a: Daniel Salafranca Barreda. d.salafranca@crimina.es R e i c R e v i s t a E s p a ñ o l a d e I n v e s t i g a c i ó n C r i m i n o l ó g i c a
This represents one of several sections of "A Bibliography Related to Crime Scene Interpretation with Emphases in Geotaphonomic and Forensic Archaeological Field Techniques, Nineteenth Edition" (The complete bibliography is also included at ResearchGate.net.). This is the most recent edition of a bibliography containing resources for multiple areas of crime scene, and particularly outdoor crime scene, investigations. It replaces the prior edition and contains approximately 10,000 additional citations. As an ongoing project, additional references, as encountered, will be added to future editions.
This section of the bibliography includes references to the effects non-insect scavengers impart to human remains before, during, and after death. A subcategory of bitemark evidence accompanies scavenging more because they share the method than the motive. Although articles on cannibalism are included and might be considered scavenging in some survival situations, most involve research into typically violent sexual encounters between victims and attackers. Because such wound trauma is so often a signature of masochistic or sadomasochistic encounters, references in Criminal and Cultural Behaviour should be considered toward understanding motivations and contexts behind this and other taphonomic clues left on a body. The bitemark citations herein do not focus on all topics of forensic odontology. Instead, those specifically addressing bitemark evidence are included. The collection of DNA evidence should always be from possible bitemarks. Therefore, there are cross-references between this category and DNA Evidence. Likewise, articles on trace evidence such as lipstick/gloss and facial hair may be pertinent to a particular investigation in which bitemarks are found on skin or food associated with a crime scene. If DNA should be considered a component of bitemark evidence, then so should friction ridge detail. Latent and patent hand and finger prints may be recovered from a bitten victim’s skin or substrates near or under the body.
Whether it is the family dog or mountain lion in the wild, animals will exploit available food sources and human remains may be among them. What goes in, must come out; so this sub-category of the bibliography dovetails with Fecal and Coprolite Evidence under Miscellaneous Trace Evidence. The most numerous and voracious of any scavengers are among forensically significant insects. The volume of research and citations in forensic entomology have justified a category of its own within this bibliography.
Aim
The development of conservation plans, including those dealing with invasive species, is underpinned by the need to obtain reliable and accurate data. However, in many cases responding rapidly is equally critical.
Location
The data were obtained from the Hebridean Mink Project, which was set up with the objective of removing mink from North Uist, Benbecula and South Uist.
Methods
Here, we introduce an extension of the Dirichlet process mixture ( DPM ) model of geographic profiling that can be used to estimate source locations of invasions directly from spatial point pattern data without the need to specify dispersal parameters. We use this model to analyse a biological invasion of American mink ( Neovison vison ) in the Hebrides.
Results
Our results suggest that sightings data – which are relatively easy and quick to acquire – can be used to capture much of the information about sources of invasive species that is obtained from the harder to acquire and more intensive trap data.
Main conclusion
These results have important implications for the development of conservation plans and, in this case, in the early stages of biological invasions, when interventions are most likely to be successful.
Present report is the documentation of shark attack on Indo-Pacific humpback dolphin, which was washed ashore at Mithapur coast in Gujarat, India. The crescent shaped tooth impregnation on the deceased dolphin revealed it was attacked by shark. As the animal was injured only in seven places, perhaps, the attack was due to competitive interaction between shark and dolphin. Morphometric measurements and description of the wounds on the dolphin were recorded and documented. This is the first report of shark attack on Indo-Pacific humpback dolphin from Gujarat coast. [
1. Fishing spans all oceans and the impact on ocean predators such as sharks and rays is largely
unknown. A lack of data and complicated jurisdictional issues present particular challenges for
assessing and conserving high seas biodiversity. It is clear, however, that pelagic sharks and rays of
the open ocean are subject to high and often unrestricted levels of mortality from bycatch and
targeted fisheries for their meat and valuable fins.
2. These species exhibit a wide range of life-history characteristics, but many have relatively low
productivity and consequently relatively high intrinsic vulnerability to over-exploitation. The
IUCN}World Conservation Union Red List criteria were used to assess the global status of 21
oceanic pelagic shark and ray species.
3. Three-quarters (16) of these species are classified as Threatened or Near Threatened. Eleven
species are globally threatened with higher risk of extinction: the giant devilray is Endangered, ten
sharks are Vulnerable and a further five species are Near Threatened. Threat status depends on the
interaction between the demographic resilience of the species and intensity of fisheries exploitation.
4. Most threatened species, like the shortfin mako shark, have low population increase rates and
suffer high fishing mortality throughout their range. Species with a lower risk of extinction have
either fast, resilient life histories (e.g. pelagic stingray) or are species with slow, less resilient life
histories but subject to fisheries management (e.g. salmon shark).
5. Recommendations, including implementing and enforcing finning bans and catch limits, are
made to guide effective conservation and management of these sharks and rays.
The degree to which white sharks, Carcharodon carcharias, are social while hunting is unclear. Our aim was to describe the behavior and interactions among white sharks hunting seals
near a seal colony. We attached ultrasonic beacons to five adult white sharks, 4.5–5.2 m long, and recorded their movements
and behavior toward each other over a 15-day period in October 1997 at Año Nuevo Island, California. This site is home to
colonies of four species of seals and sea lions. Two additional sharks, females 5.5 and 4.7 m in length, were later tracked
intensively during periods of 12 and 3 days during October 1998 and November 1999, respectively. We recorded stomach temperature
(indicative of feeding on warm-bodied seals) and swimming depths from the 5.5-m female, swimming speed and depth from the
4.7-m female. We monitored the movements and behavior of these sharks using an array of sonobuoys moored near the island;
the receptive field measured 1 km2. Our principal findings were: (1) the sharks spent a mean time of 39.5% of each day patrolling within the receptive field;
(2) no shark ever moved far out of it; (3) the sharks spent an equal amount of time and activity in the receptive field at
all times of the day, daytime, twilight, and nighttime; (4) movements with respect to the island rookery were most often back
and forth parallel to the shoreline, (5) tracks of three sharks, tagged at the same time and place, overlapped more often
than those of the other two sharks; and (6) some sharks patrolled certain areas in the field preferentially, but there was
no conclusive evidence that they defended these areas as territories. Feeding appeared to be infrequent: only two likely feeding
bouts occurred during a cumulative 78-day/shark period that individuals were monitored at Año Nuevo Island. The behavior and
movements of the sharks were consistent with a hunting strategy, in which individuals search for prey independently but, at
the same time, remain close enough to each other to “sense” and exploit a kill by any one of them by joining in on the kill
to feed.
We describe a method, radio-acoustic-positioning (RAP), for continuously monitoring the movements and behavior of large marine
animals. An ultrasonic transmitter on the animal can be localized with high spatial accuracy (2 to 10 m) within an area of
1 km2, based on when the same pulse arrives at three hydrophones on sonobuoys aligned in a triangular array. Radio transceivers
communicate with the base station, where the x and y coordinates of the subject are calculated using hyperbolic equations. The base station plots the individual's position and
displays information from the tag's sensors in real time on a computer monitor before saving the data on a disk. The base
station must be situated either on land or on a vessel within the reception range of the three buoys. We used a RAP system
to monitor the movements and behavior of white sharks (Carcharodon carcharias) near the elephant seal rookery at Año Nuevo Island in central California. This type of system is an ideal tool to study
the predatory behavior of the white shark because individuals patrol for seal prey within a zone <1300 m from shore. We describe
the operation of the system, including acoustic triangulation, range of detection and positioning, data acquisition and analysis,
and positional accuracy. We illustrate the implementation of the method and its advantages and disadvantages by describing
an ongoing study of white shark hunting-behavior. Sample data from this study are presented to illustrate specific points.
We describe the movements of five sharks within the receiving range and their behavior relative to each other. The RAP system
is compared to other complementary tracking methods. We conclude that this system has great potential for monitoring the movements
and behavior of large marine animals within a relatively small zone, where feeding or reproduction takes place.
This paper presents information on the movements of white sharks, Carcharodon carcharias, at the South Farallon Islands (SFI), central California. Acoustic telemetry techniques provided preliminary data on the diurnal space utilization, movement patterns and swimming depths of four white sharks, ranging from approximately 3.7 to 4.9m in length. Sharks swam within about 10m of the bottom to depths of approximately 30m, but in deeper water they tended to stray more from the bottom. Activity spaces for time periods tracked ranged from 1.84 to 9.15km2. Indications are that an inverse relationship exists between length and activity space. During the time tracked, larger individuals swam within particular areas around the islands whereas smaller individuals did not restrict their movements in the same manner. Values of a site attachment index were inversely related to length for all sharks tracked. The site attachment indices, apparent inverse relationship between total length and activity space and observations on telemetered and other known individuals support a hypothesis that larger sharks possess site fidelity in their search for prey at SFI, within and between years. With the high frequency of predation by white sharks on juvenile northern elephant seals at SFI in the fall, the majority of the sharks' movements are probably related to their search for these pinniped prey. These data provide preliminary evidence that white sharks at SFI may search for prey by swimming in a particular area over a number of days or weeks, traversing the area in a manner which maximizes coverage, and swimming close to the bottom or at a distance far enough from the surface to remain cryptic from prey.
We present both an empirical study and a behavioural game model exploring a predator–prey game between white sharks, Carcharodon carcharias, and Cape fur seals, Arctocephalus pusillus pusillus, around a small island colony in South Africa. Behavioural tactics used by adult seals appear to account for the variance in risk from sharks, while shark tactics seem more influenced by the behaviour of pup seals, probably because pup seals engage in riskier behaviours. A dynamic game model of the interaction predicts that, if pups and adult seals account for risk in a similar manner, then tactic selection used by sharks and seals should be more evenly distributed across all possible options. Instead, a second model in which pups were constrained to choose the riskiest option produced evolutionarily stable strategy (ESS) solutions for both species that more closely approximated the tactics recorded, suggesting that behavioural variation within subgroups of a population should be accounted for when modelling predator–prey interactions. These results also suggest that pups may act as initiators in a behaviourally mediated indirect interaction with adult seals, mediated by the behaviour of their common shark predator; this would represent the first record of an intergenerational two-species indirect interaction.
Geographic profiling was originally developed as a statistical tool for use in criminal cases, particularly those involving serial killers and rapists. It is designed to help police forces prioritize lists of suspects by using the location of crime scenes to identify the areas in which the criminal is most likely to live. Two important concepts are the buffer zone (criminals are less likely to commit crimes in the immediate vicinity of their home) and distance decay (criminals commit fewer crimes as the distance from their home increases). In this study, we show how the techniques of geographic profiling may be applied to animal data, using as an example foraging patterns in two sympatric colonies of pipistrelle bats, Pipistrellus pipistrellus and P. pygmaeus, in the northeast of Scotland. We show that if model variables are fitted to known roost locations, these variables may be used as numerical descriptors of foraging patterns. We go on to show that these variables can be used to differentiate patterns of foraging in these two species.
Between 1997 and 2003, there were 2088 natural predations by white sharks (Carcharodon carcharias) on Cape fur seals (Arctocephalus pusillus pusillus) and 121 strikes on towed seal-shaped decoys were documented from observation vessels at Seal Island, South Africa. White sharks at Seal Island appear to selectively target lone, incoming young of the year Cape fur seals at or near the surface. Most attacks lasted < 1 min and consisted of a single breach, with predatory success rate decreasing rapidly with increasing duration and number of subsequent breaches. A white shark predatory ethogram,composed of four phases and 20 behavioural units, is presented, including four varieties of initial strike and 11 subsequent behaviour units not previously defined in the literature. Behaviour units scored from 210 predatory attacks revealed that, for both successful and unsuccessful attacks, Polaris Breach was the most commonly employed initial strike, while Surface Lunge was the most frequent second event, closely followed by Lateral Snap. Examination of video footage, still images, and tooth impressions in decoys indicated that white sharks at Seal Island bite prey obliquely using their anterolateral teeth via a sudden lateral snap of the jaws and not perpendicularly with their anterior teeth, as previously supposed. Analysis of white shark upper tooth morphology and spacing suggest the reversed intermediate teeth of white sharks occur at the strongest part of the jaw and produce the largest wound. White sharks predatory success at Seal Island is greatest (55%) within one hour of sunrise and decrease rapidly with increasing ambient light; the sharks cease active predation on seals of sunrise and decreases rapidly with increasing ambient light; the sharks cease active predation on seals when success rate drops to +/- 40%; this is the first evidence of cessation of foraging at unproductive times by any predatory fish. At Seal Island, white shark predatory success is significantly lower at locations where frequency of predation is highest, suggesting that white sharks may launch suboptimal strikes in areas of greatest intraspecific competition; this is the first evidence of social influence on predation in any elasmobranch. Idiosyncratic predatory behaviours and elevated success rates of known individual white sharks at Seal Island suggest some degree of trial-and-error learning. A hypothetical decision tree is proposed that models predatory behaviour of white sharks attacking Capr fur seals at the surface.
Impacts of chronic overfishing are evident in population depletions worldwide, yet indirect ecosystem effects induced by predator removal from oceanic food webs remain unpredictable. As abundances of all 11 great sharks that consume other elasmobranchs (rays, skates, and small sharks) fell over the past 35 years, 12 of 14 of these prey species increased in coastal northwest Atlantic ecosystems. Effects of this community restructuring have cascaded downward from the cownose ray, whose enhanced predation on its bay scallop prey was sufficient to terminate a century-long scallop fishery. Analogous top-down effects may be a predictable consequence of eliminating entire functional groups of predators.
Geographic profiling (GP) was originally developed as a statistical tool to help police forces prioritize lists of suspects in investigations of serial crimes. GP uses the location of related crime sites to make inferences about where the offender is most likely to live, and has been extremely successful in criminology. Here, we show how GP is applicable to experimental studies of animal foraging, using the bumble-bee Bombus terrestris. GP techniques enable us to simplify complex patterns of spatial data down to a small number of parameters (2-3) for rigorous hypothesis testing. Combining computer model simulations and experimental observation of foraging bumble-bees, we demonstrate that GP can be used to discriminate between foraging patterns resulting from (i) different hypothetical foraging algorithms and (ii) different food item (flower) densities. We also demonstrate that combining experimental and simulated data can be used to elucidate animal foraging strategies: specifically that the foraging patterns of real bumble-bees can be reliably discriminated from three out of nine hypothetical foraging algorithms. We suggest that experimental systems, like foraging bees, could be used to test and refine GP model predictions, and that GP offers a useful technique to analyse spatial animal behaviour data in both the laboratory and field.
Overexploitation threatens the future of many large vertebrates. In the ocean, tunas and sea turtles are current conservation
concerns because of this intense pressure. The status of most shark species, in contrast, remains uncertain. Using the largest
data set in the Northwest Atlantic, we show rapid large declines in large coastal and oceanic shark populations. Scalloped
hammerhead, white, and thresher sharks are each estimated to have declined by over 75% in the past 15 years. Closed-area models
highlight priority areas for shark conservation, and the need to consider effort reallocation and site selection if marine
reserves are to benefit multiple threatened species.
Spatial and temporal records of 146 predatory attacks by white sharks (Carcharodon carcharias) on four species of pinnipeds, one bird, and one human at the South Farallon Islands, Central California, from late Aug. to early Dec. 1986-89 are presented. During each 3.5-mo period, attacks were (1) unevenly distributed in bouts separated by hiatuses in predation, (2) paired temporally within the same day, (3) at similar times and locations on consecutive days, and (4) all during daylight hours. Predation was observed most often within 450 m of shore, with a decrease in attack frequency with increasing depth. Within this high-risk zone, predation was concentrated near coastal departure and entry points of pinnipeds, and the predatory attack positions formed linear patterns leading away from the island. Consecutive predatory attacks were often near each other, yet at times alternated between localities on either side of the island.
Predator–prey interactions play a central role in the behavior, ecology, and population biology of most taxa and are critical in community dynamics. For elasmobranchs, most studies focus only on their role as a predator. This is an important oversight as most species are both predator and prey, at least for periods of their life history. In this chapter I place predator–prey interactions in the rich theoretical framework that has developed over the last several decades, from both a behavioral and a trophic perspective. Rather than compiling an exhaustive list of predator–prey interactions, I develop a framework for these interactions highlighting relevant elasmobranch examples. While there have been intriguing studies, there is much work to do and I hope that this chapter will help stimulate studies based on hypothesis testing that will help answer unresolved issues in the behavior and ecology of elasmobranchs.
One of the most problematic aspects of predatory violent crime is the volume of tips and suspects generated through their investigation. Traditional police methods are not always sufficient and detectives need alternative tactics to assist them in these types of cases. Geographic profiling, a strategic information management system designed to support investigative efforts in cases of serial murder, rape and arson, is one such approach. Other topics discussed include: introduction; investigative difficulties; geographic profiling; and conclusion. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Prey availability and predation risk are important determinants of habitat use, but their importance may vary across spatial scales. In many marine systems, predator and prey distributions covary at large spatial scales, but do no coincide at small spatial scales. We investigated the influences of prey abundance and tiger shark (Galeocerdo cuvier) predation risk on Indian Ocean bottlenose dolphin (Tursiops aduncus) habitat use across multiple spatial scales, in Shark Bay, Western Australia. Dolphins were distributed between deep and shallow habitats and across microhabitats within patches approximately proportional to prey density when shark abundance was low. When shark abundance was high, foraging dolphins greatly reduced their use of dangerous, but productive, shallow patches relative to safer deep ones. Also, dolphins reduced their use of interior portions of shallow patches relative to their edges, which have higher predator density but lower intrinsic risk (i.e. a higher probability of escape in an encounter situation). These results suggest that predation risk and prey availability influence dolphin habitat use at multiple spatial scales, but intrinsic habitat risk, and not just predator encounter rate, is important in shaping dolphin space use decisions. Therefore, studies of habitat use at multiple spatial scales can benefit from integrating data on prey availability and the subcomponents of predation risk.
Effects of environmental factors on frequency and success rate of 2,546 natural predatory attacks by white sharks, Carcharodon carcharias, on Cape fur seals, Arctocephalus pusillus pusillus, were studied over an 8-year period at Seal Island, South Africa. Attacks occurred primarily during winter months (June–August). Attack frequency increased significantly during northerly winds, during high tides, and within 400m of the island, but predatory success rate decreased with proximity to the island. Attacks occurred over a depth range of 5–31m, with significantly more occurring at depths of 26–30m. Attack frequency and success rate increased significantly at low light levels. These results are compared with published effects of environmental factors on white shark predation frequency at the Farallon Islands, California, and discussed in terms of the Predation Cycle. Suggestions for future work at this site are offered.
Understanding the foraging behavior and spatial distribution of top predators is crucial to gaining a complete understanding of communities. However, studies of top predators are often logistically difficult and it is important to develop appropriate methods for identifying factors influencing their spatial distribution. Sharks are top predators in many marine communities, yet no studies have quantified the habitat use of large predatory sharks or determined the factors that might influence shark spatial distributions. We used acoustic telemetry and animal-borne video cameras ("Crittercam") to test the hypothesis that tiger shark (Galeocerdo cuvier) habitat use is determined by the availability of their prey. We also used Crittercam to conduct the first investigation of foraging behavior of tiger sharks. To test for habitat preferences of sharks, the observed proportion of time in each habitat for each individual was compared to the predicted values for that individual based on correlated random walk and track randomization methods. Although there was individual variation in habitat use, tiger sharks preferred shallow seagrass habitats, where their prey is most abundant. Despite multiple encounters with potential prey, sharks rarely engaged in prolonged high-speed chases, and did not attack prey that were vigilant. We propose that the tiger sharks' foraging tactic is one of stealth, and sharks rely upon close approaches to prey in order to be successful. This study shows that using appropriate analysis techniques and a variety of field methods it is possible to elucidate the factors influencing habitat use and gain insights into the foraging behavior of elusive top predators.
Researchers generally categorize motile foraging behavior into 3 strategies: ambush, cruise, and saltatory searching. During
saltatory searches, predators move from one location to the next, frequently pausing to scan for prey that are hard to detect
and widely distributed. We investigated whether 1) the foraging strategy of free-living common marmosets conforms to the strategy;
2) scanning occurs solely when the individual is stationary; 3) the environment (dense and sparse vegetation) influences foraging
behavior; and 4) the age of the marmosets is related to their foraging behavior. Bezerra carried out the observations in a
32-ha fragment of Atlantic Forest in the Northeast of Brazil and in an adjacent condominium. Using the focal sampling method,
we observed 31 common marmosets, including adults, juveniles, and infants, Bezerra recorded the following behaviors (in dense
and sparse vegetation): locomotion (subdivided into minor locomotion—moving distances ≤1m; major locomotion—moving distances
>1m), scan, pause, and capture. The frequency of scanning behavior was significantly greater when individuals were stationary.
Adults and juveniles exhibited the clearest differentiation in terms of locomotion, both adjusting the behavior in accordance
with the environment; periods of major locomotion were more frequent in sparse vegetation, whereas minor locomotion was more
frequent in dense vegetation. In contrast, infants exhibited major locomotion more frequently in dense vegetation. We conclude
that common marmosets use a saltatory strategy when foraging, and that their foraging behavior is plastic, changing both with
the age of the individual and with the density of the vegetation.
Based on three years of study in the Serengeti National Park, George B. Schallerâs The Serengeti Lion describes the vast impact of the lion and other predators on the vast herds of wildebeest, zebra, and gazelle for which the area is famous. The most comprehensive book available on the lion, this classic work includes the authorâs findings on all aspects of lion behavior, including its social system, population dynamics, hunting behavior, and predation patterns. âIf you have only enough time to read one book about field biology, this is the one I recommend.ââEdward O. Wilson, Science âThis book conveys not only the fascination of its particular study of lion behavior but the drama and wonder and beauty of the intimate interdependence of all living things.ââSaturday Review âThis is an important book, not just for its valuable information on lions, but for its broad, open, and intelligent approach to problems that cut across the fields of behavior, populations, ecology, wildlife management, evolution, anthropology, and comparative biology.ââRichard G. Van Gelder, Bioscience
Risk effects arise when prey alter their behavior in response to predators, and these responses carry costs. Empirical studies have found that risk effects can be large. Nonetheless, studies of predation in vertebrate conservation and management usually consider only direct predation. Given the ubiquity and strength of behavioral responses to predators by vertebrate prey, it is not safe to assume that risk effects on dynamics can be ignored. Risk effects can be larger than direct effects. Risk effects can exist even when the direct rate of predation is zero. Risk effects and direct effects do not necessarily change in parallel. When risk effects reduce reproduction rather than survival, they are easily mistaken for limitation by food supply.
Recent studies document unprecedented declines in marine top predators that can initiate trophic cascades. Predicting the wider ecological consequences of these declines requires understanding how predators influence communities by inflicting mortality on prey and inducing behavioral modifications (risk effects). Both mechanisms are important in marine communities, and a sole focus on the effects of predator-inflicted mortality might severely underestimate the importance of predators. We outline direct and indirect consequences of marine predator declines and propose an integrated predictive framework that includes risk effects, which appear to be strongest for long-lived prey species and when resources are abundant. We conclude that marine predators should be managed for the maintenance of both density- and risk-driven ecological processes, and not demographic persistence alone.
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(Eds). Cape town: WWF South Africa.
You can swim but you can't hide
- Dulvy N.K.
Running the gauntlet
- Laroche R.K.