Data were collected over ten consecutive parturition seasons (2013-2023) as part of long-term, fisheries-independent surveys carried out as a collaboration with the Centre de Recherches Insulaires et Observatoire de l’Environnement (CRIOBE) and the Physioshark Research Programme around Moorea, French Polynesia (17° 30’ S, 149° 50’ W). During these surveys, neonatal and juvenile blacktip reef sharks were caught using a 50 × 1.5 m gillnet with 5-cm mesh size set perpendicular to shore. Please see accompanying text (McInturf et al., 2025; Ecology & Evolution) for details.

Data were collected over ten consecutive parturition seasons (2013-2023) as part of long-term, fisheries-independent surveys carried out as a collaboration with the Centre de Recherches Insulaires et Observatoire de l’Environnement (CRIOBE) and the Physioshark Research Programme around Moorea, French Polynesia (17° 30’ S, 149° 50’ W). During these surveys, neonatal and juvenile blacktip reef sharks were caught using a 50 × 1.5 m gillnet with 5-cm mesh size set perpendicular to shore. Please see accompanying text (McInturf et al., 2025; Ecology & Evolution) for details.

Animal movements are typically influenced by multiple environmental factors simultaneously and individuals vary in their response to this environmental heterogeneity. Therefore, understanding how environmental aspects, including biotic, abiotic and anthropogenic factors, influence the movements of wild animals is an important focus of wildlife research and conservation. We apply exponential random graph models (ERGMs) to analyse movement networks of a bull shark population in a network of acoustic receivers and identify the effects of environmental, social or other types of covariates on their movements. We found that intra- and interspecific factors often had stronger effects on movements than environmental variables. ERGMs proved to be a potentially useful tool for studying animal movement network data especially in the context of spatial attribute heterogeneity.

Genetic relatedness in animal societies is often a factor that drives the structure of social groups. In the marine world, most studies which have investigated this question have focused on marine mammals such as whales and dolphins. For sharks, recent studies have demonstrated preferential associations among individuals from which social communities emerge. Assortment patterns have been found according to phenotypic or behavioural traits but the role of genetic relatedness in shaping the social structure of adult shark populations has, to the best our knowledge, never been investigated. Here, we used a social network analysis crossed with DNA microsatellite genotyping to investigate the role of the genetic relatedness in the social structure of a blacktip reef shark (Carcharhinus melanopterus) population. Based on data from 156 groups of sharks, we used generalized affiliation indices to isolate social preferences from non-social associations, controlling for the contribution of sex, size, gregariousness, spatial and temporal overlap on social associations, to test for the influence of genetic relatedness on social structure. A double permutation procedure was employed to confirm our results and account for issues arising from potentially elevated type I and type II error rates. Kinship was not a predictor of associations and affiliations among sharks at the dyad or community levels as individuals tended to associate independently of the genetic relatedness among them. The lack of parental care in this species may contribute to the breakdown of family links in the population early in life, thereby preventing the formation of kin-based social networks.

Anthropogenic ocean acidification (OA) is a threat to coral reef fishes, but few studies have investigated responses of high-trophic-level predators, including sharks. We tested the effects of 72-hr exposure to OA-relevant elevated partial pressures of carbon dioxide (pCO2) on oxygen uptake rates, acid–base status, and haematology of newborn tropical blacktip reef sharks (Carcharhinus melanopterus). Acute exposure to end-of-century pCO2 levels resulted in elevated haematocrit (i.e. stress or compensation of oxygen uptake rates) and blood lactate concentrations (i.e. prolonged recovery) in the newborns. Conversely, whole blood and mean corpuscular haemoglobin concentrations, blood pH, estimates of standard and maximum metabolic rates, and aerobic scope remained unaffected. Taken together, newborn blacktip reef sharks appear physiologically robust to end-of-century pCO2 levels, but less so than other, previously investigated, tropical carpet sharks. Our results suggest peak fluctuating pCO2 levels in coral reef lagoons could still physiologically affect newborn reef sharks, but studies assessing the effects of long-term exposure and in combination with other anthropogenic stressors are needed.

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