Concede or clash? Solitary sharks competing for food assess rivals to decide

Brena, Pierpaolo F.; Mourier, Johann; Planes, Serge; Clua, Éric

doi:10.1098/rspb.2018.0006

Cited by 23 publications

(24 citation statements)

References 68 publications

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“…Hierarchical social organization in these locations could allow mature females to group with preferred social partners and simultaneously avoid unwanted mating attempts by mature males. Familiarity has been shown to reduce aggression among sharks within recently established social hierarchies (Brena et al 2018). Social gathering points could also facilitate exchange of information (e.g.…”

Section: Discussionmentioning

confidence: 99%

Social preferences and network structure in a population of reef manta rays

Perryman

Venables

Tapilatu

et al. 2019

Behav Ecol Sociobiol

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Understanding how individual behavior shapes the structure and ecology of populations is key to species conservation and management. Like many elasmobranchs, manta rays are highly mobile and wide ranging species threatened by anthropogenic impacts. In shallow-water environments these pelagic rays often form groups, and perform several apparently socially-mediated behaviors. Group structures may result from active choices of individual rays to interact, or passive processes. Social behavior is known to affect spatial ecology in other elasmobranchs, but this is the first study providing quantitative evidence for structured social relationships in manta rays. To construct social networks, we collected data from more than 500 groups of reef manta rays over five years, in the Raja Ampat Regency of West Papua. We used generalized affiliation indices to isolate social preferences from non-social associations, the first study on elasmobranchs to use this method. Longer lasting social preferences were detected mostly between female rays. We detected assortment of social relations by phenotype and variation in social strategies, with the overall social network divided into two main communities. Overall network structure was characteristic of a dynamic fission-fusion society, with differentiated relationships linked to strong fidelity to cleaning station sites. Our results suggest that fine-scale conservation measures will be useful in protecting social groups of M. alfredi in their natural habitats, and that a more complete understanding of the social nature of manta rays will help predict population responses to anthropogenic pressures, such as increasing disturbance from dive-tourism.

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Section: Discussionmentioning

confidence: 99%

Social preferences and network structure in a population of reef manta rays

Perryman

Venables

Tapilatu

et al. 2019

Behav Ecol Sociobiol

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“…However, its efficacy in our study appears to be lower than in Huveneers et al (2018), with 42.3% of our trials ending in a success, as opposed to 56% for Huveneers et al (2018). This discrepancy may be caused by several factors, such as the possible competition between sharks, with sometimes up to six or seven sharks present during a single trial, competing for a small reward 28 , 29 . The high number of bull sharks present on site may be an additional motivator to ignore, or better tolerate, the electric fields produced by the deterrents.…”

Section: Discussionmentioning

confidence: 99%

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

Gauthier¹,

Chateauminois²,

Hoarau³

et al. 2020

Sci Rep

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Although relatively rare, human-shark interactions and sharks bites are increasing globally, which has led to the development of various mitigation measures. Electric shark deterrents (ESDs) have, so far, been the most effective personal deterrents, but have only been scientifically tested on one of the species most frequently responsible for shark bites, i.e. white shark (Carcharodon carcharias). We tested the effectiveness of five ESDs (E-Shark Force, NoShark, Rpela v2, Freedom + Surf, Freedom + Surf—Shortboard) on bull sharks, Carcharhinus leucas, over a period of 21 days in September 2019, in New Caledonia. Standardised bait was attached 30 cm below an experimental board that had an active ESD for up to 15 min, or until a bull shark touched the bait or the board. We compared the numbers of baits taken, numbers of passes and reactions around the board, as well as the distance between the sharks and the board among ESDs and against a control board with bait and no active ESD. The Freedom + Surf was the most effective ESD, reducing the amounts of baits taken by 42.3%, while the Rpela v2 and Freedom + Surf—Shortboard also significantly reduced the number of baits taken by 16.5% and 16.2% respectively. Mean distance between sharks and the bait was not affected by the ESDs, but the number of approaches and the proportion of reactions were both significantly higher when the Freedom + Surf was active compared to other ESDs. The effectiveness of all ESDs decreased over time, with the likelihood of the bait being taken increasing and the number of approaches and distance between sharks and the bait decreasing. Our findings show that the ability of ESDs to deter bull shark varies between products, with the Freedom + Surf resulting in the most behavioural changes, followed by the Rpela v2 and Freedom + Surf—Shortboard. However, none of the products tested completely stopped sharks from taking the bait.

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“…In addition, by-product mutualism and pseudo-reciprocity are simple mechanisms that can lead to increased foraging success, cooperative hunting. While evidence of shark cooperation has not been confirmed, gregarious behaviour can have several benefits in sharks (Jacoby et al 2012), including increased foraging success by hunting in groups (Weideli et al 2015; Mourier et al 2016), protection from predators (Mourier, Planes, et al 2013), or increased tolerance relationships and reduced aggression rate (Brena et al 2018). Heterospecific foraging associations have been found to develop and increase predation success (Labourgade et al 2020), which suggests that sharks can benefit from hunting associations without associating with kin.…”

Section: Discussionmentioning

confidence: 99%

“…Sharks represent an interesting and unique model to explore the extent to which individuals interact with genetically related associates due to ecological traits that differ from most social vertebrates. Like most social animals, sharks are now increasingly recognised as being capable of complex social interactions, developing preferred social associations (Guttridge et al 2009; Jacoby et al 2010; Mourier et al 2012), showing unexpected learning abilities (Guttridge et al 2013; Mourier et al 2017) and developing patterns of leadership and dominance hierarchy (Guttridge et al 2011; Jacoby et al 2016; Brena et al 2018). However, contrary to many social organisms, reef sharks do not show parental care and almost all shark species drop their progeny in specific nurseries outside adult habitats and leave them to interact by themselves (Mourier and Planes 2013).…”

Section: Introductionmentioning

confidence: 99%

Kinship does not predict the structure of a shark social network

Mourier

Planes

2019

Preprint

Self Cite

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17The role of relatedness in animal societies has received important consideration as a process 18 driving social groups. In the marine world, most studies which have investigated this question 19 have focused on marine mammals such as whales and dolphins. For sharks, recent studies 20 have demonstrated preferential associations among individuals from which social 21 communities emerge. Assortment patterns have been found according to phenotypic or 22 behavioural traits but the role of genetic relatedness and family structure in shaping the social 23 structure of adult shark populations has never been investigated. Here, we used a social 24 network analysis crossed with DNA microsatellite genotyping to investigate the role of the 25 genetic relatedness in the social structure of a blacktip reef shark (Carcharhinus 26 melanopterus) population. We found an established social network spatially organized but 27 dynamic through time with different communities merging during the mating periods. Such 28 recombination shows the males being more gregarious. Kinship was not a predictor of 29 associations among sharks both at the dyad or community levels as individuals tended to 30 associate independently and randomly regardless of the genetic relatedness between 31 individuals. The lack of parental care in this species may contribute to the breakdown of 32 family links in the population early in life, thereby preventing the formation of kin-based 33 social networks. 34 35

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Concede or clash? Solitary sharks competing for food assess rivals to decide

Cited by 23 publications

References 68 publications

Social preferences and network structure in a population of reef manta rays

Social preferences and network structure in a population of reef manta rays

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

Kinship does not predict the structure of a shark social network

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