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Negaprion brevirostris. Visual representations of juvenile lemon shark social networks, for all group sizes. (a) July 14, 2006 (daily snapshot), (b) May to Dec 2006, (c) May to Dec 2007. Larger node size signifies larger shark body length. Thicker line edges between individuals signifies a higher number of groups that they were observed to interact in together. We only included groups that were at least 10 min apart (see 'Materials and methods' for details). Female = filled nodes, male = unfilled nodes
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For marine predators there is a paucity of studies on social behaviour, and even fewer
studies have quantified interactions between individuals. In the present study, we looked at the social
structure and leadership of free-ranging juvenile lemon shark Negaprion brevirostris in a known
aggregation site, Bimini, the Bahamas. Observations of these sh...
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White sharks (Carcharodon carcharias) are circumglobally distributed large apex predators. While ecologically important, there is very limited study of their social behaviour. Although evident in other large, apex marine predators (e.g. toothed whales) and smaller elasmobranchs (e.g. blacktip reef sharks), the ability of any large pelagic elasmobra...
Citations
... Particularly, adult and sub-adult blue sharks are known to segregate by sex and size [13]. In nurseries, lemon sharks, Negaprion brevirostris, form size-driven aggregations that confer anti-predatory and foraging advantages [86]. While it is known that teleost fishes and marine mammals are capable of social recognition [87][88][89], kinship-driven aggregations in sharks have been widely overlooked to date. ...
... While it is known that teleost fishes and marine mammals are capable of social recognition [87][88][89], kinship-driven aggregations in sharks have been widely overlooked to date. Kinship may be playing a role in the aggregation of juvenile lemon sharks [86]; and small spotted catsharks, Scyliorhinus canicula, have social preferences for familiar sharks but not necessarily for relatives [90]. Our finding highlights the need for further investigation into potential kinship-driven social aggregations of blue sharks. ...
The blue shark, Prionace glauca, is the most abundant pelagic shark in the open ocean but its vulnerability remains poorly understood while being one of the most fecund sharks. In the Mediterranean Sea, the blue shark is listed as Critically Endangered (CR) by the International Union for Conservation of Nature. The species is facing a strong decline due to fishing, and scientific data regarding its genetic structure and vulnerability are still lacking. Here, we investigated the genetic diversity, demographic history, and population structure of the blue shark within the Mediterranean Sea, from samples of the Gulf of Lion and Malta, using sequences of the mtDNA control region and 22 microsatellite markers. We also compared our mitochondrial data to previous studies to examine the Atlantic-Mediterranean population structure. We assessed the blue shark’s genetic vulnerability in the Mediterranean basin by modelling its effective population size. Our results showed a genetic differentiation between the Atlantic and the Mediterranean basins, with limited gene flow between the two areas, and distinct demographic histories making the Mediterranean population an independent management unit. Within the Mediterranean Sea, no sign of population structure was detected, suggesting a single population across the Western and Central parts of the sea. The estimated effective population size was low and highlighted the high vulnerability of the Mediterranean blue shark population, as the estimated size we calculated might not be sufficient to ensure the long-term persistence of the population. Our data also provide additional evidence that the Gulf of Lion area acts as a nursery for P. glauca, where protection is essential for the conservation strategy of the species in the Mediterranean.
... A network represents a set of nodes and edges obtained using graph theory, allowing the study of pairwise interactions between nodes (Jacoby and Freeman 2016; Mourier et al. 2018). Network analysis can be conducted using various data-collection techniques such as mark-recapture (Guttridge et al. 2011;Mourier et al. 2017), acoustic telemetry Jacoby et al. , 2021 or observation (e.g. diving observations: Mourier et al. 2012; Mourier and Planes 2021). ...
The spotted gully shark Triakis megalopterus (Triakidae) is a mesopredatory species endemic to southern
Africa. It is currently listed as Least Concern on the IUCN Red List in accordance with an estimated increase in
population size, general release by recreational linefishers and incidental catches in the commercial linefisheries.
Previous research suggests this species to be resident, and as such it is likely to receive protection in coastal
marine protected areas (MPAs). However, its ecology and movement behaviour remain poorly studied. This study
employed acoustic telemetry to provide information on the species’ movements along the coast of the Western
Cape Province, South Africa. We used network analyses to investigate movement randomness, associations
between individuals, sexual segregation, and the effectiveness of MPAs. Our findings reveal nonrandom
movements as well as patterns of co-occurrence between individuals. Spatial network analysis suggested
sexual segregation, because areas of high use (Walker Bay and De Hoop) differed between males and females.
Co-occurrences were observed exclusively in Walker Bay, chiefly between males, with no co-occurrence found
between females. The tagged spotted gully sharks were not detected extensively within existing MPA boundaries,
though there was no significant difference between their movements inside and outside protected areas for both
sexes.
... More recently, quantitative methods have been developed to identify social associations (i.e. Guttridge et al., 2011 ;Mourier et al., 2017 ;Perryman et al., 2022 ). For example, Mourier et al., (2017) used acoustic receiver data and social network analysis to show nonrandom associations in Port Jackson sharks ( Heterodontus portusjacksoni). ...
Elasmobranchs are highly diverse in movement, sensory capacity, and behavioural responses to the environment, leading to differences in the function and nature of associations and interactions between individuals, populations, and species. The term “aggregation” has been widely and variably used to describe co-occurrence across elasmobranch species, but its defining criteria remain vague and indeterminate. The lack of standardized terminology hinders comparisons across studies, species, and systems. It can cause misinterpretation about the drivers of aggregation formation or grouping behaviour and limits the impact of elasmobranch behavioural research. Here, we propose generalizable definitions of aggregation and supporting terms, adapted from more mature socioecological theory in other systems, which can be applied across elasmobranchs. We discuss the drivers and types of elasmobranch aggregations, detail the criteria required to identify an aggregation based on our definition, and offer direction on future methods and reporting to advance the field. These proposed definitions and reporting protocols standardize the study of elasmobranch socioecology, will generate greater understanding of the mechanisms underlying behaviour and distribution across species, and support more cross-system comparisons. Finally, this information can offer greater predictive power into when and how aggregations may form, leading to more proactive management strategies to mitigate anthropogenic threats.
... Guttridge et al. (2009) reviewed learning reported in earlier studies of elasmobranchs, and since then there has been more interest in intelligent elasmobranch behaviour. They have been found to use cognitive maps (Papastamatiou et al., 2011;Mourier et al., 2011), recognize conspecifics as individuals (Myrberg & Gruber, 1974;Guttridge et al., 2011;Jacoby et al., 2014), use the Earth's magnetic field to navigate (Keller et al., 2021) and to be capable of social learning (Guttridge et al., 2013). Stingrays (Potamotrygon castexi) learned to use water as a tool to extract food (Kuba et al., 2010). ...
... An example is the blacktips' reaction to perceiving a scuba diver (who once accompanied the author to a session) for the first time. After disappearing beyond visual range for a full 10 min, they suddenly came forward in Follow-Formation: 35 blacktips in two lines, single-file, following two sharks who had shown leadership tendencies in the past (Guttridge et al., 2011). Possibly the bonnethead sharks were not stimulated to take Follow-Formation by the type of unexpected events that regularly confronted the wild blacktips. ...
The chondrichthyan lineage diverged from the osteichthyan line around 440 million years ago, resulting in a vast evolutionary gulf between modern elasmobranchs and other vertebrates. Though this has supported the assumption that as an ancient line, elasmobranchs are dangerously stupid, intelligent actions including social interactions have been noted in the field, while laboratory studies have confirmed a variety of cognitive capacities. Yet, due to fear of sharks and the difficulties of observing them in their aquatic environments, few ethological studies have been done, so their natural behaviour remains little known. On noting that the blacktip reef shark, Carcharhinus melanopterus , displayed complex actions during incidental meetings, a long-term ethological study of the species was carried out on the north shore of Mo’orea Island, French Polynesia. During the 6.5 years of the study, new behaviours continued to present. The 35 context-specific actions identified as comprising the behavioural repertoire of C. melanopterus are described.
... Group sizes within mobulid nurseries tend to be smaller than adult aggregations (e.g., maximum of 19 juvenile individuals in M. munkiana compared with adult aggregations of thousands of individuals) (Palacios et al., 2021). In some of these nursery areas there is segregation by size (Palacios et al., 2021), similar to descriptions in other juvenile elasmobranchs (Guttridge et al., 2011), which could be the result of differences in swimming capabilities or habitat preferences at different size/age stages (Jacoby et al., 2012). ...
Manta and devil rays (mobulids) are filter feeding elasmobranchs with extreme K-selective life histories found circumglobally from temperate to tropical waters. Their vulnerability to fisheries exploitation, bycatch, boat collisions, entanglement and unregulated tourism is exacerbated by their aggregative behavior. Studies have identified aggregation sites around the world for all nine mobulid species, with these groupings varying from a few individuals to thousands. However, the terminology used to define these aggregations and the drivers underpinning them remain unclear, hindering the development of effective management and conservation strategies. Here, we analyze aggregation behavior for mobulid species, providing consistent definitions for grouping events and summarizing the existing research on drivers and environmental factors triggering these events. We find that aggregation behaviors facilitate socializing and key life history functions in mobulids, including feeding, courtship and mating, predation avoidance, cleaning, and thermoregulation. Conservation threats and management mitigation opportunities associated with aggregations sites include fisheries, tourism, spatial protection, and climate change. Finally, we highlight knowledge gaps for future research prioritization and developments in the field for the identification of aggregation sites, the study of aggregation size and demographics and the functions and timing of aggregations.
... Guttridge et al. (2009) reviewed learning reported in earlier studies of elasmobranchs, and since then there has been more interest in intelligent elasmobranch behaviour. They have been found to use cognitive maps (Papastamatiou et al., 2011;Mourier et al., 2011), recognize conspecifics as individuals (Myrberg & Gruber, 1974;Guttridge et al., 2011;Jacoby et al., 2014), use the Earth's magnetic field to navigate (Keller et al., 2021) and to be capable of social learning (Guttridge et al., 2013). Stingrays (Potamotrygon castexi) learned to use water as a tool to extract food (Kuba et al., 2010). ...
... An example is the blacktips' reaction to perceiving a scuba diver (who once accompanied the author to a session) for the first time. After disappearing beyond visual range for a full 10 min, they suddenly came forward in Follow-Formation: 35 blacktips in two lines, single-file, following two sharks who had shown leadership tendencies in the past (Guttridge et al., 2011). Possibly the bonnethead sharks were not stimulated to take Follow-Formation by the type of unexpected events that regularly confronted the wild blacktips. ...
The chondrichthyan lineage diverged from the osteichthyan line around 440 million years ago, resulting in a vast evolutionary gulf between modern elasmobranchs and other vertebrates. Though this has supported the assumption that sharks are ancient, dangerous, and binary-minded, intelligent actions including social interactions have been noted in the field, while laboratory studies have confirmed a variety of cognitive capacities. Yet, due to fear of sharks and the difficulties of observing them in their aquatic environments, few ethological studies have been done, so their natural behaviour remains little known. On noting that Carcharhinus melanopterus displayed complex actions during incidental meetings, a long-term ethological study of the species was carried out on the north shore of Mo’orea Island, French Polynesia. During the 6.5 years of the study, new behaviours continued to present. The 35 context-specific actions identified as comprising the behavioural repertoire of C. melanopterus are described.
... The housing pen was a large oval (15 m x 5 m) divided into three sections, to keep the sharks in sizematched groups. This was important for the sociability assay because juvenile lemon sharks are known to prefer following larger conspecifics (Guttridge et al., 2011). The sociability pen was circular ( ...
... As intraspecific competition increases, more explorative individuals may benefit from actively avoiding conspecifics to reduce competition and exploit patchy and ephemeral food resources. In contrast, in years when the subpopulation size is small, and resources are less limited, more explorative individuals may benefit more from associating with conspecifics in the mangrove inlets that offer protection from predators (Guttridge et al., 2011). As such, we expected that an increase in intraspecific competition would lead to more explorative sharks being less social. ...
In behavioural ecology, interest in the study of animal personality (i.e. consistent individual differences in behaviour) has
increased in the last two decades as it is believed to have important ecological and evolutionary consequences. These
consequences are especially pronounced when personality covaries with other behaviours (i.e. behavioural syndrome) or with
life-history (i.e. pace-of-life syndrome). So far, studies of personality on behavioural, and pace-of-life-syndromes have produced
ambiguous outcomes, and the prominence of studies on captive animals in the literature may be a reason for inconclusive
results.
To address this knowledge gap, we tested personality in wild juvenile lemon shark (Negaprion brevirostris) from 2012 to 2018
to investigate the emergence of behavioural and pace-of-life-syndromes under relevant ecological pressures.
We first explored how to quantify meaningful personality traits in our study species. We then investigated (1) whether a
behavioural syndrome existed between two consistent traits and whether the appearance of the syndrome was context
dependent, (2) whether a growth-mortality trade-off was mediated by personality and (3) whether personality could predict the
foraging habitat of sharks and whether this link was context-dependent.
Overall, our research suggest that ecological conditions play a crucial role in the emergence and the shaping of personality and
trait association. This work offers a possible explanation for the ambiguous results of previous studies and highlights the
importance of increasing the focus on wild study systems in future animal personality research. Along with recent revisions of
the personality research framework, this work may help paving the way for future shark-personality research.
... In recent years, research on various elasmobranch species (cartilaginous fishes including sharks, rays and skates) has shown that their populations can be socially structured (Mourier et al., 2012;. Like social birds and mammals, elasmobranchs maintain social preferences between individuals (Guttridge et al., 2009;Perryman et al., 2019), and their social interactions can have adaptive functions (e.g. in learning or information transfer; Guttridge et al., 2011;Keller et al., 2017;Vila Pouca et al., 2020;Papastamatiou et al., 2020) that contribute to emergent population structuring (Mourier & Planes, 2021;Papastamatiou et al., 2020). Sharks are known to have highly variable behavioural phenotypes relating to exploration and movement, sufficient to comprise individual personalities (Jacoby et al., 2014;Byrnes & Brown, 2016;Finger et al., 2017Finger et al., , 2018. ...
Knowledge of the drivers of fine-scale spatial ecology in wide-ranging marine species is vital to understand population structuring and conserve threatened species. Movements and habitat use are likely to be strongly influenced by social relationships between individuals, and social units within animal populations may be subject to distinct selective pressures. Here we used passive acoustic telemetry and network-based analyses to investigate the site visit patterns and social affiliations of reef manta rays, Mobula alfredi, in Raja Ampat, West Papua. Acoustic transmitters were externally deployed on 27 rays that were tracked for up to 110 days. Visit profiles were retrieved from nine acoustic receivers positioned in clusters at known aggregation sites, enabling analysis of movement behaviour and social processes at various spatial scales. We utilized Bayesian inference and a double permutation method to address issues in sampling and hypothesis testing on social networks constructed from automated telemetry data. We found that social affiliations were assorted into spatially defined communities which remained stable over several weeks to months, although many affiliations were short lived. Interindividual variability in detection profiles was correlated with social network metrics. Individuals with high levels of site attachment had stronger social affiliations, while individuals that regularly attended different receiver clusters were more central to the overall social network. These results suggest that reef manta ray movements, habitat preferences and social relationships should be understood as linked behavioural processes for which variability between individuals and groups may drive emergent population structure. Future research and local management of manta rays will likely benefit from identifying how, where and why social gatherings occur.
... Learning in elasmobranchs was noted in earlier studies as reviewed by Guttridge et al. (2009). Sharks use cognitive maps (Papastamatiou et al. 2011;, recognize conspecifics as individuals (Myrberg & Gruber 1974, Guttridge et al. 2011Jacoby et al. 2016), use the Earth's magnetic field to navigate (Keller et al. 2021) and are capable of social learning (Guttridge et al. 2013). Stingrays (Potamotrygon castexi) learned to use water as a tool to extract food (Kuba et al. 2010), and have been observed to play (Burghardt 2015). ...
... The blackfins accelerated beyond visual range and for ten minutes no shark appeared. Then Sharks #3 and #109, both of whom had shown leadership tendencies in many other situations (Guttridge et al. 2011;Porcher 2021), came in Parallel through the coral canyons with the rest of the three dozen blackfins in Followformation behind them in two single-file lines. The leaders did a fast Close approach to the scuba diver and he was enveloped in a swirl of swiftly moving sharks-he fell over backwards. ...
... When familiar blackfins met they would usually either Swim-by each other or briefly Parallel. Dyads, with a variety of acquaintances, were found in bull sharks identified during ecotourism in Fiji (Thibault et al. 2021), in juvenile lemon sharks (Gruber et al. 2011), and around feeding aggregations in white sharks off South Africa (Findlay et al. 2016). ...
The chondrichthyan lineage diverged from the osteichthyan line 440 million years ago, resulting in a vast evolutionary gulf between modern elasmobranchs and other vertebrates. Though this has supported the assumption that sharks are ancient, dangerous, and binary-minded, the few ethological studies done have noted intelligent actions including social exchanges. Yet their behaviour remains little known. On seeing that Carcharhinus melanopterus displayed complex actions during incidental meetings, a long-term ethological study of the species was carried out using artificial aggregations, at several sites in the fringe lagoon of Mo’orea Island, French Polynesia. Short and long-term behaviour was recorded in 473 individuals, including an ethogram, roaming patterns, social interactions, and cognition. C. melanopterus is considered sedentary, yet the home range could also be viewed as a place to pause between travels, for most individuals left for long periods. The study community and its visitors travelled in correlation with the lunar phase, in groups of up to six individuals, socializing with conspecifics encountered along the way, and displaying fluid social dynamics. C. melanopterus was highly alert to danger yet prone to investigate novel objects, a combination that generated a variety of tactics to remain hidden while investigating the environment. Basic to this was the use of the visual limit for escape or to screen their presence, indicating an awareness of being present and observable. Using their other senses, they could focus their attention on events beyond visual range and made swift decisions to act as circumstances unfolded. In their non-territorial, non-hierarchical society, any shark could lead, but it was usually the same ones that did so. Therefore, unusual individuals had a significant effect on events through social learning, suggesting the potential for culture. Actions in a variety of situations suggested complex cognition, and individuals displayed both positive and negative subjective states including playfulness.
... Many elasmobranch species, including manta rays and other mobulid rays (Mobula spp.), use shallow and sheltered habitats like lagoons as nursery areas for newborns (Heupel et al., 2007;Stewart et al., 2018b). Reef lagoons provide several benefits for juvenile elasmobranchs, such as calm sea conditions, protection from large predators, reliable food availability, and opportunities for social interaction with conspecifics (Guttridge et al., 2011;Jacoby et al., 2012;McCauley et al., 2014;Rojas et al., 2014;Heupel et al., 2019). Occupying sheltered nursery areas may also contribute to higher chances of newborn survival by enabling individuals to grow in a safe environment and become better equipped to later escape predators and find diffuse prey (Branstetter, 1990). ...
The behaviour and spatial use patterns of juvenile manta rays within their critical nursery habitats remain largely undocumented. Here, we report on the horizontal movements and residency of juvenile reef manta rays (Mobula alfredi) at a recently discovered nursery site in the Wayag lagoon, Raja Ampat, Indonesia. Using a multi-disciplinary approach, we provide further corroborative evidence that the lagoon serves as an important M. alfredi nursery. A total of 34 juvenile rays were photo-identified from 47 sightings in the sheltered nursery between 2013–2021. Five (14.7%) of these individuals were resighted for at least 486 days (~1.3 years), including two juveniles resighted after 641 and 649 days (~1.7 years), still using the nursery. Visually estimated (n=34) disc widths (DW) of juveniles using the nursery site ranged from 150–240 cm (mean ± SD: 199 ± 19), and the DW of two juveniles measured using drones were 218 and 219 cm. Five juveniles were tracked using GPS-enabled satellite transmitters for 12–69 days (mean ± SD: 37 ± 22) in 2015 and 2017, and nine juveniles were tracked using passive acoustic transmitters for 69–439 days (mean ± SD: 182 ± 109) from May 2019–September 2021. Satellite-tracked individuals exhibited restricted movements within Wayag lagoon. The minimum core activity space (50% Utilisation Distribution-UD) estimated for these five individuals ranged from 1.1–181.8 km² and the extent of activity space (95% UD) between 5.3–1,195.4 km² in area. All acoustically tagged individuals displayed high residency within the nursery area, with no acoustic detections recorded outside the lagoon in the broader Raja Ampat region. These juveniles were detected by receivers in the lagoon throughout the 24 h diel cycle, with more detections recorded at night and different patterns of spatial use of the lagoon between day and night. The observed long-term residency of juvenile M. alfredi provides further compelling evidence that the Wayag lagoon is an important nursery area for this globally vulnerable species. These important findings have been used to underpin the formulation of management strategies to specifically protect the Wayag lagoon, which will be instrumental for the survival and recovery of M. alfredi populations in Raja Ampat region.
